Merge branch 'develop' into RELEASE

Merge pull request #481 from starseeker/string_pool
Fixes for Clang compilation
2026-08-07 13:50:54 -04:00 · 2026-08-07 13:48:39 -04:00 · 2026-08-07 14:20:19 +00:00 · 2026-08-04 09:32:15 -04:00 · 2026-08-04 09:27:48 -04:00 · 2026-08-03 13:17:07 -04:00
178 changed files with 127192 additions and 38823 deletions
@@ -44,11 +44,11 @@ jobs:

      - name: Test
        run: |
-          cd build && ctest -j1 .
+          cd build && ctest --verbose -j1 .

  linux:
    name: Ubuntu Latest GCC
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
    strategy:
      fail-fast: true
    steps:
@@ -86,11 +86,11 @@ jobs:

      - name: Test
        run: |
-          cd build && ctest -j1 . -C Release
+          cd build && ctest --verbose -j1 . -C Release

  linux_clang:
    name: Ubuntu Latest Clang
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
    strategy:
      fail-fast: true
    steps:
@@ -128,7 +128,7 @@ jobs:

      - name: Test
        run: |
-          cd build && ctest -j1 . -C Release
+          cd build && ctest --verbose -j1 . -C Release


  osx:
@@ -160,62 +160,68 @@ jobs:

      - name: Test
        run: |
-          cd build && ctest -j1 . -C Release
+          cd build && ctest --verbose -j1 . -C Release

  brlcad_linux:
    name: BRL-CAD Linux step-g Test
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
    strategy:
      fail-fast: true
    steps:
      - name: Setup - CMake
        uses: lukka/get-cmake@latest

-      - name: Setup - Ninja
-        uses: seanmiddleditch/gha-setup-ninja@master
-
      - name: Setup - System
        env:
          DEBIAN_FRONTEND: noninteractive
        run: |
          sudo apt-get update
-          # Install dev tools
-          sudo apt-get install re2c lemon
+          sudo apt-get install re2c astyle xsltproc libxml2-utils
+          sudo apt-get install xserver-xorg-dev libx11-dev libxi-dev libxext-dev libglu1-mesa-dev libfontconfig-dev
+          sudo apt-get install zlib1g-dev libpng-dev libjpeg-dev libtiff-dev libeigen3-dev libgdal-dev libassimp-dev libopencv-dev
          sudo apt-get clean

+      - name: Clone bext
+        run: |
+          git clone https://github.com/BRL-CAD/bext.git
+          cd bext/stepcode
+          cmake -E rm -r stepcode
+          git clone --depth 1 https://github.com/stepcode/stepcode.git -b develop
+          cd ../..
+
+      - name: Build bext
+        run: |
+          cmake -E make_directory bext_build
+          cmake -S bext -B bext_build -DCMAKE_BUILD_TYPE=Release -DUSE_GDAL=OFF -DUSE_TCL=OFF -DUSE_QT=OFF -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}\bext_output
+          cmake --build bext_build --config Release -j2
+          # We only need the build ouputs (bext_output) after this point, so
+          # clean up to save space for the main BRL-CAD build.
+          cmake -E rm -rf bext
+          cmake -E rm -rf bext_build
+
+
      - name: Checkout
        run: |
          git clone --depth 1 https://github.com/BRL-CAD/brlcad.git -b main
-          cd brlcad/src/other/ext && rm -rf stepcode
-          git clone --depth 1 https://github.com/stepcode/stepcode.git -b develop
-          # Ordinarily BRL-CAD keeps track of what files are supposed to be
-          # present in the repository.  In this case we're not interested in
-          # updating the list to the working stepcode filelist, so use an empty
-          # list instead
-          echo "set(stepcode_ignore_files)" > stepcode.dist
-          cd ../../../../
-

      - name: Configure
        run: |
-          export PATH=$ENV{GITHUB_WORKSPACE}:$PATH
-          cd brlcad
-          cmake -S . -G Ninja -B build -DENABLE_ALL=ON -DCMAKE_BUILD_TYPE=Release -DEXT_BUILD_VERBOSE=ON
+          cmake -E make_directory brlcad_build
+          cd brlcad_build
+          cmake -S ../brlcad -DBRLCAD_EXT_DIR=${{ github.workspace }}\bext_output -DBRLCAD_ENABLE_GDAL=OFF -DBRLCAD_ENABLE_TCL=OFF -DBRLCAD_ENABLE_QT=OFF -G Ninja
          cd ..

      - name: Build
        run: |
-          export PATH=$ENV{GITHUB_WORKSPACE}:$PATH
-          cd brlcad
-          cmake --build build --config Release --target step-g
+          cd brlcad_build
+          cmake --build . --target step-g
          cd ..

      - name: Test
        run: |
-          export PATH=$ENV{GITHUB_WORKSPACE}:$PATH
-          cd brlcad/build
-          ./bin/step-g ../db/nist/NIST_MBE_PMI_3.stp -o nist3.g
-          cd ../..
+          cd brlcad_build
+          ./bin/step-g ../brlcad/db/nist/NIST_MBE_PMI_3.stp -o nist3.g
+          cd ..


  brlcad_windows:
@@ -227,9 +233,6 @@ jobs:
      - name: Setup - CMake
        uses: lukka/get-cmake@latest

-      - name: Setup - Ninja
-        uses: seanmiddleditch/gha-setup-ninja@master
-
      - name: Add github workspace to path
        # https://github.community/t/deprecated-add-path/136621
        run: echo "$ENV{GITHUB_WORKSPACE}" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
@@ -240,38 +243,44 @@ jobs:
      - name: Add cl.exe to PATH
        uses: ilammy/msvc-dev-cmd@v1

+      - name: Clone bext
+        run: |
+          git clone https://github.com/BRL-CAD/bext.git
+          cd bext/stepcode
+          cmake -E rm -r stepcode
+          git clone --depth 1 https://github.com/stepcode/stepcode.git -b develop
+          cd ../..
+
+      - name: Build bext
+        shell: powershell
+        run: |
+          cmake -E make_directory bext_build
+          cmake -S bext -B bext_build -DCMAKE_BUILD_TYPE=Release -DUSE_GDAL=OFF -DUSE_TCL=OFF -DUSE_QT=OFF -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}\bext_output
+          cmake --build bext_build --config Release -j2
+          # We only need the build ouputs (bext_output) after this point, so
+          # clean up to save space for the main BRL-CAD build.
+          cmake -E rm -rf bext
+          cmake -E rm -rf bext_build
+
+
      - name: Checkout
        run: |
          git clone --depth 1 https://github.com/BRL-CAD/brlcad.git -b main
-          cd brlcad/src/other/ext
-          cmake -E rm -r stepcode
-          git clone --depth 1 https://github.com/stepcode/stepcode.git -b develop
-          # Ordinarily BRL-CAD keeps track of what files are supposed to be
-          # present in the repository.  In this case we're not interested in
-          # updating the list to the working stepcode filelist, so use an empty
-          # list instead
-          echo "set(stepcode_ignore_files)" > stepcode.dist
-          cd ../../../../

      - name: Configure
        run: |
-          cd brlcad && cmake -S . -B build -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DCMAKE_CXX_COMPILER="cl.exe" -DSC_ENABLE_TESTING=ON
-          cd ..
-          # We do the following in order to help ensure files are "flushed"
-          # to disk before compilation is attempted
-          # https://superuser.com/a/1553374/1286142
-          powershell Write-VolumeCache C
-          powershell Write-VolumeCache D
+          cmake -E make_directory brlcad_build
+          cmake -S brlcad -B brlcad_build -DCMAKE_BUILD_TYPE=Release -DBRLCAD_EXT_DIR=${{ github.workspace }}\bext_output -DBRLCAD_ENABLE_GDAL=OFF -DBRLCAD_ENABLE_TCL=OFF -DBRLCAD_ENABLE_QT=OFF -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DCMAKE_CXX_COMPILER="cl.exe"

      - name: Build
        run: |
-          cd brlcad/build
-          ninja -j1 -v step-g
-          cd ../..
+          cd brlcad_build
+          cmake --build . --config Release --target step-g
+          cd ..

      - name: Test
        run: |
-          cd brlcad/build
-          ./bin/step-g.exe ../db/nist/NIST_MBE_PMI_3.stp -o nist3.g
-          cd ../..
+          cd brlcad_build
+          ./bin/step-g.exe ../brlcad/db/nist/NIST_MBE_PMI_3.stp -o nist3.g
+          cd ..

@@ -1,5 +1,6 @@
 # Common build directories used in the source tree
 /build
+/build-*
 /.build

 # Temporary files
@@ -19,3 +20,6 @@
 # Tool specific patterns
 *.kdev4
 .kdev_include_paths
+
+# Parser generator intermediate files
+*.out
@@ -129,6 +129,18 @@ if (SC_ENABLE_COVERAGE AND ${CMAKE_C_COMPILER_ID} STREQUAL "GNU")
  set(CMAKE_MODULE_LINKER_FLAGS_DEBUG "-fprofile-arcs -ftest-coverage" CACHE STRING "Extra linker flags required by code coverage" FORCE)
 endif (SC_ENABLE_COVERAGE AND ${CMAKE_C_COMPILER_ID} STREQUAL "GNU")

+option(SC_ENABLE_ADDRESS_SANITIZER "Enable AddressSanitizer instrumentation" OFF)
+option(SC_ENABLE_UNDEFINED_SANITIZER "Enable UndefinedBehaviorSanitizer instrumentation" OFF)
+option(SC_ENABLE_THREAD_SANITIZER "Enable ThreadSanitizer instrumentation" OFF)
+
+if(SC_ENABLE_THREAD_SANITIZER AND
+   (SC_ENABLE_ADDRESS_SANITIZER OR SC_ENABLE_UNDEFINED_SANITIZER))
+  message(FATAL_ERROR
+    "SC_ENABLE_THREAD_SANITIZER must use a separate build from "
+    "AddressSanitizer and UndefinedBehaviorSanitizer"
+  )
+endif()
+
 option(SC_BUILD_EXPRESS_ONLY "Only build express parser." OFF)
 mark_as_advanced(SC_BUILD_EXPRESS_ONLY)

@@ -155,6 +167,111 @@ include(SC_Regenerate)
 # create config.h header
 include(SC_Config_Headers)

+# Apply sanitizer instrumentation after configure-time feature tests so their
+# try-compile executables do not depend on sanitizer runtime behavior.  Keep
+# link flags explicit for CMake 3.12 compatibility (add_link_options was added
+# in CMake 3.13).
+if(SC_ENABLE_ADDRESS_SANITIZER OR
+   SC_ENABLE_UNDEFINED_SANITIZER OR
+   SC_ENABLE_THREAD_SANITIZER)
+  if(MSVC)
+    message(FATAL_ERROR "STEPcode sanitizer builds are not yet supported with MSVC")
+  endif()
+
+  include(CMakePushCheckState)
+  include(CheckCSourceCompiles)
+  include(CheckCXXSourceCompiles)
+  include(CheckCCompilerFlag)
+  include(CheckCXXCompilerFlag)
+
+  set(_sc_sanitizer_compile_options)
+  set(_sc_sanitizer_link_options)
+
+  function(sc_require_sanitizer FLAG RESULT_PREFIX)
+    cmake_push_check_state()
+    set(CMAKE_REQUIRED_FLAGS "${FLAG}")
+    list(APPEND CMAKE_REQUIRED_LIBRARIES "${FLAG}")
+    check_c_source_compiles("int main(void) { return 0; }" ${RESULT_PREFIX}_C_SUPPORTED)
+    check_cxx_source_compiles("int main() { return 0; }" ${RESULT_PREFIX}_CXX_SUPPORTED)
+    cmake_pop_check_state()
+    if(NOT ${RESULT_PREFIX}_C_SUPPORTED OR NOT ${RESULT_PREFIX}_CXX_SUPPORTED)
+      message(FATAL_ERROR
+        "STEPcode sanitizer mode was requested, but the C/C++ compiler and "
+        "linker do not support ${FLAG}"
+      )
+    endif()
+  endfunction()
+
+  if(SC_ENABLE_ADDRESS_SANITIZER)
+    sc_require_sanitizer("-fsanitize=address" SC_ASAN)
+    list(APPEND _sc_sanitizer_compile_options -fsanitize=address)
+    list(APPEND _sc_sanitizer_link_options -fsanitize=address)
+    # exp2cxx is executed during the build to generate schema bindings.  It
+    # remains address-instrumented, but leak checking a short-lived build
+    # tool is both outside the test scope and unsupported under common build
+    # tracers/sandboxes.  Limit this environment to schema generation; CTest
+    # and installed tools retain the user's normal ASan settings.
+    set(SC_SCHEMA_GENERATOR_ENVIRONMENT "ASAN_OPTIONS=detect_leaks=0")
+  endif()
+
+  if(SC_ENABLE_UNDEFINED_SANITIZER)
+    sc_require_sanitizer("-fsanitize=undefined" SC_UBSAN)
+    cmake_push_check_state()
+    set(CMAKE_REQUIRED_FLAGS "-fsanitize=undefined")
+    list(APPEND CMAKE_REQUIRED_LIBRARIES "-fsanitize=undefined")
+    check_c_compiler_flag(
+      "-fno-sanitize-recover=undefined"
+      SC_UBSAN_C_NO_RECOVER_SUPPORTED
+    )
+    check_cxx_compiler_flag(
+      "-fno-sanitize-recover=undefined"
+      SC_UBSAN_CXX_NO_RECOVER_SUPPORTED
+    )
+    cmake_pop_check_state()
+    if(NOT SC_UBSAN_C_NO_RECOVER_SUPPORTED OR
+       NOT SC_UBSAN_CXX_NO_RECOVER_SUPPORTED)
+      message(FATAL_ERROR
+        "STEPcode's fail-fast UndefinedBehaviorSanitizer mode was requested, "
+        "but the C/C++ compiler does not support "
+        "-fno-sanitize-recover=undefined"
+      )
+    endif()
+    list(APPEND _sc_sanitizer_compile_options
+      -fsanitize=undefined
+      -fno-sanitize-recover=undefined
+    )
+    list(APPEND _sc_sanitizer_link_options -fsanitize=undefined)
+  endif()
+
+  if(SC_ENABLE_THREAD_SANITIZER)
+    sc_require_sanitizer("-fsanitize=thread" SC_TSAN)
+    list(APPEND _sc_sanitizer_compile_options -fsanitize=thread)
+    list(APPEND _sc_sanitizer_link_options -fsanitize=thread)
+  endif()
+
+  check_c_compiler_flag("-fno-omit-frame-pointer" SC_SANITIZER_C_FRAME_POINTER_SUPPORTED)
+  check_cxx_compiler_flag("-fno-omit-frame-pointer" SC_SANITIZER_CXX_FRAME_POINTER_SUPPORTED)
+  if(SC_SANITIZER_C_FRAME_POINTER_SUPPORTED)
+    list(APPEND _sc_sanitizer_compile_options
+      $<$<COMPILE_LANGUAGE:C>:-fno-omit-frame-pointer>
+    )
+  endif()
+  if(SC_SANITIZER_CXX_FRAME_POINTER_SUPPORTED)
+    list(APPEND _sc_sanitizer_compile_options
+      $<$<COMPILE_LANGUAGE:CXX>:-fno-omit-frame-pointer>
+    )
+  endif()
+
+  add_compile_options(${_sc_sanitizer_compile_options})
+  string(JOIN " " _sc_sanitizer_link_flags ${_sc_sanitizer_link_options})
+  foreach(_sc_link_type EXE SHARED MODULE)
+    set(
+      CMAKE_${_sc_link_type}_LINKER_FLAGS
+      "${CMAKE_${_sc_link_type}_LINKER_FLAGS} ${_sc_sanitizer_link_flags}"
+    )
+  endforeach()
+endif()
+
 if(NOT DEFINED SC_SDAI_ADDITIONAL_EXES_SRCS)
  set(SC_SDAI_ADDITIONAL_EXES_SRCS "" CACHE STRING "Source files for additional executables to be linked with SDAI libs")
 endif(NOT DEFINED SC_SDAI_ADDITIONAL_EXES_SRCS)
@@ -230,4 +347,3 @@ endforeach(_msg ${CONFIG_END_MESSAGES})
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -5,7 +5,7 @@ This repo was moved and renamed in May 2012. Previously, it was at
 http://github.com/mpictor/StepClassLibrary

 Some are duplicates of changes recorded in the BRL-CAD repo:
-http://brlcad.svn.sourceforge.net/viewvc/brlcad/brlcad/trunk/src/other/step/?view=log
+https://github.com/BRL-CAD/brlcad/tree/158beae4556d94821938368951546384cba53107/src/other/ext/stepcode

 Pre-BRL-CAD changes:
 ************************************************************************
@@ -51,7 +51,13 @@ Installation
  -DSC_BUILD_SCHEMAS=ALL
    - Added to make use of ctest easier. If SC_BUILD_SCHEMAS == ALL,
      then CMake adds each *.exp file found in data/.
-  -DSC_BUILD_TYPE=Release
+  -DSC_EXP2CXX_API_VERSION=2
+    - opts in to compact descriptor-driven SELECTs and dependency-bounded
+      entity headers in the generated C++ API.
+    - clients include the entity headers they use (for example,
+      entity/SdaiProduct.h); schema.h no longer expands every entity class.
+    - version 1 remains the default for source compatibility.
+  -DCMAKE_BUILD_TYPE=Release
    - this causes binaries to be built without debugging information
    - without this, cmake defaults to a Debug build

@@ -27,17 +27,29 @@ endmacro(P21_TESTS sfile)
 # create p21read_sdai_*, lazy_sdai_*, any exes listed in SC_SDAI_ADDITIONAL_EXES_SRCS
 macro(SCHEMA_EXES)
  RELATIVE_PATH_TO_TOPLEVEL(${CMAKE_CURRENT_SOURCE_DIR} RELATIVE_PATH_COMPONENT)
-  SC_ADDEXEC(p21read_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/test/p21read/p21read.cc;${RELATIVE_PATH_COMPONENT}/src/test/p21read/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME} stepdai stepcore stepeditor steputils TESTABLE)
+  if(BUILD_SHARED_LIBS)
+    SC_ADDEXEC(p21read_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/test/p21read/p21read.cc;${RELATIVE_PATH_COMPONENT}/src/test/p21read/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME} stepdai stepcore stepeditor steputils TESTABLE)
+  elseif(BUILD_STATIC_LIBS)
+    SC_ADDEXEC(p21read_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/test/p21read/p21read.cc;${RELATIVE_PATH_COMPONENT}/src/test/p21read/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME}-static stepeditor-static stepcore-static stepdai-static steputils-static TESTABLE)
+  endif()
  if(NOT WIN32)
-    SC_ADDEXEC(lazy_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/cllazyfile/lazy_test.cc;${RELATIVE_PATH_COMPONENT}/src/cllazyfile/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME} steplazyfile stepdai stepcore stepeditor steputils TESTABLE)
+    if(BUILD_SHARED_LIBS)
+      SC_ADDEXEC(lazy_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/cllazyfile/lazy_test.cc;${RELATIVE_PATH_COMPONENT}/src/cllazyfile/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME} steplazyfile stepdai stepcore stepeditor steputils TESTABLE)
+    elseif(BUILD_STATIC_LIBS)
+      SC_ADDEXEC(lazy_${PROJECT_NAME} SOURCES "${RELATIVE_PATH_COMPONENT}/src/cllazyfile/lazy_test.cc;${RELATIVE_PATH_COMPONENT}/src/cllazyfile/sc_benchmark.cc" LINK_LIBRARIES ${PROJECT_NAME}-static steplazyfile-static stepeditor-static stepcore-static stepdai-static steputils-static TESTABLE)
+    endif()
  endif(NOT WIN32)

  #add user-defined executables
  foreach(src ${SC_SDAI_ADDITIONAL_EXES_SRCS})
    get_filename_component(name ${src} NAME_WE)
    get_filename_component(path ${src} ABSOLUTE)
-    SC_ADDEXEC(${name}_${PROJECT_NAME} SOURCES ${src} LINK_LIBRARIES ${PROJECT_NAME} stepdai stepcore stepeditor steputils TESTABLE)
+    if(BUILD_SHARED_LIBS)
+      SC_ADDEXEC(${name}_${PROJECT_NAME} SOURCES ${src} LINK_LIBRARIES ${PROJECT_NAME} stepdai stepcore stepeditor steputils TESTABLE)
+    elseif(BUILD_STATIC_LIBS)
+      SC_ADDEXEC(${name}_${PROJECT_NAME} SOURCES ${src} LINK_LIBRARIES ${PROJECT_NAME}-static stepcore-static stepdai-static stepeditor-static steputils-static TESTABLE)
    #set_target_properties(${name}_${PROJECT_NAME} PROPERTIES COMPILE_FLAGS "${${PROJECT_NAME}_COMPILE_FLAGS} -I${path}")
+    endif()
  endforeach(src ${SC_SDAI_ADDITIONAL_EXES_SRCS})
 ENDMACRO(SCHEMA_EXES)

@@ -77,25 +89,40 @@ macro(SCHEMA_TARGETS expFile schemaName sourceFiles)
  # schema scanner comes up with a short schema name for PROJECT() (which sets ${PROJECT_NAME})
  message(STATUS "Will generate ${${PROJECT_NAME}_file_count} C++ files for ${PROJECT_NAME}.")

-  add_custom_target(generate_cpp_${PROJECT_NAME} DEPENDS exp2cxx ${expFile} ${sourceFiles} SOURCES ${sourceFiles})
+  set(_schema_generated_files)
+  foreach(_schema_source ${sourceFiles})
+    list(APPEND _schema_generated_files "${CMAKE_CURRENT_SOURCE_DIR}/${_schema_source}")
+  endforeach()
+  add_custom_target(generate_cpp_${PROJECT_NAME} DEPENDS exp2cxx ${expFile} ${_schema_generated_files} SOURCES ${_schema_generated_files})
  # this calls a cmake script because it doesn't seem to be possible
  # to divert stdout, stderr in cmake except via execute_process
-  add_custom_command(OUTPUT ${sourceFiles}
+  add_custom_command(OUTPUT ${_schema_generated_files}
    COMMAND ${CMAKE_COMMAND} -DEXE=\"$<TARGET_FILE:exp2cxx>\"  -DEXP=\"${expFile}\"
    -DONESHOT=\"${SC_GENERATE_CXX_ONESHOT}\" -DSDIR=\"${CMAKE_CURRENT_LIST_DIR}\"
+    -DCHUNK_SIZE=\"${SC_EXP2CXX_CHUNK_SIZE}\"
+    -DAPI_VERSION=\"${SC_EXP2CXX_API_VERSION}\"
+    -DLATE_BOUND=\"${SC_EXP2CXX_LATE_BOUND}\"
+    -DCOMPAT_NAMES=\"${SC_EXP2CXX_COMPAT_NAMES}\"
+    -DMETADATA_PROFILE=\"${SC_EXP2CXX_METADATA}\"
+    -DGENERATOR_ENVIRONMENT=\"${SC_SCHEMA_GENERATOR_ENVIRONMENT}\"
    -P ${SC_CMAKE_DIR}/SC_Run_exp2cxx.cmake
+    DEPENDS exp2cxx ${expFile}
    WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}
    COMMENT "[exp2cxx] Generating ${${PROJECT_NAME}_file_count} C++ files for ${PROJECT_NAME}."
  )
-  include_directories(
+  set(_schema_include_dirs
    ${CMAKE_CURRENT_SOURCE_DIR}         ${SC_SOURCE_DIR}/src/cldai          ${SC_SOURCE_DIR}/src/cleditor
    ${SC_SOURCE_DIR}/src/clutils        ${SC_SOURCE_DIR}/src/clstepcore     ${SC_SOURCE_DIR}/src/cllazyfile
    ${SC_SOURCE_DIR}/src/cllazyfile/judy/src
  )
-  # if testing is enabled, "TESTABLE" sets property EXCLUDE_FROM_ALL and prevents installation
+  # Schema libraries should be installed by default
  if(BUILD_SHARED_LIBS)
-    SC_ADDLIB(${PROJECT_NAME} SHARED SOURCES ${sourceFiles} LINK_LIBRARIES stepdai stepcore stepeditor steputils TESTABLE)
+    SC_ADDLIB(${PROJECT_NAME} SHARED SOURCES ${_schema_generated_files} LINK_LIBRARIES stepdai stepcore stepeditor steputils)
    add_dependencies(${PROJECT_NAME} generate_cpp_${PROJECT_NAME})
+    target_include_directories(${PROJECT_NAME} PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} PRIVATE ${_schema_include_dirs})
+    if(${PROJECT_NAME}_unity_build)
+      target_compile_definitions(${PROJECT_NAME} PRIVATE SC_SDAI_UNITY_BUILD)
+    endif()
    if(WIN32)
      target_compile_definitions("${PROJECT_NAME}" PRIVATE SC_SCHEMA_DLL_EXPORTS)
      if(MSVC)
@@ -110,10 +137,14 @@ macro(SCHEMA_TARGETS expFile schemaName sourceFiles)
    endif()
  endif()

-  if($CACHE{SC_BUILD_STATIC_LIBS})
-    SC_ADDLIB(${PROJECT_NAME}-static STATIC SOURCES ${sourceFiles} LINK_LIBRARIES stepdai-static stepcore-static stepeditor-static steputils-static TESTABLE)
+  if(BUILD_STATIC_LIBS)
+    SC_ADDLIB(${PROJECT_NAME}-static STATIC SOURCES ${_schema_generated_files} LINK_LIBRARIES stepcore-static stepdai-static stepeditor-static steputils-static)
    add_dependencies(${PROJECT_NAME}-static generate_cpp_${PROJECT_NAME})
+    target_include_directories(${PROJECT_NAME}-static PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} PRIVATE ${_schema_include_dirs})
    target_compile_definitions("${PROJECT_NAME}-static" PRIVATE SC_STATIC)
+    if(${PROJECT_NAME}_unity_build)
+      target_compile_definitions(${PROJECT_NAME}-static PRIVATE SC_SDAI_UNITY_BUILD)
+    endif()
    if(MSVC)
      target_compile_options("${PROJECT_NAME}-static" PRIVATE "/bigobj")
    endif()
@@ -133,4 +164,3 @@ endmacro(SCHEMA_TARGETS expFile schemaName sourceFiles)
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -1,10 +1,26 @@

 # if oneshot is true, don't run exp2cxx if source files exist. if schema.cc exists, assume others do
+if(NOT DEFINED API_VERSION OR "${API_VERSION}" STREQUAL "")
+  set(API_VERSION 1)
+endif()
+if(NOT DEFINED METADATA_PROFILE OR "${METADATA_PROFILE}" STREQUAL "")
+  set(METADATA_PROFILE full)
+endif()
+
 if(ONESHOT AND EXISTS "${SDIR}/schema.cc")
  message("WARNING: SC_GENERATE_CXX_ONESHOT is enabled. If generated code has been modified, it will NOT be rewritten!")
  message("This is ONLY for debugging STEPcode internals!")
 else()
-  execute_process(COMMAND ${EXE} ${EXP}
+  set(_exp2cxx_mode_args)
+  if(LATE_BOUND)
+    list(APPEND _exp2cxx_mode_args --late-bound)
+  endif()
+  if(COMPAT_NAMES)
+    list(APPEND _exp2cxx_mode_args --compat-names)
+  endif()
+  list(APPEND _exp2cxx_mode_args --metadata ${METADATA_PROFILE})
+  execute_process(COMMAND ${CMAKE_COMMAND} -E env ${GENERATOR_ENVIRONMENT}
+    ${EXE} -k ${CHUNK_SIZE} -V ${API_VERSION} ${_exp2cxx_mode_args} ${EXP}
    WORKING_DIRECTORY ${SDIR}
    RESULT_VARIABLE _res
    OUTPUT_FILE exp2cxx_stdout.txt
@@ -22,4 +38,3 @@ endif()
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -10,15 +10,23 @@ macro(SC_ADDEXEC execname)

  add_executable(${execname} ${${_arg_prefix}_SOURCES})

+  if(BUILD_STATIC_LIBS)
+    target_compile_definitions(${execname} PRIVATE SC_STATIC)
+  endif()
+
  if(DEFINED "${_arg_prefix}_LINK_LIBRARIES")
    foreach(_lib ${${_arg_prefix}_LINK_LIBRARIES})
        if($CACHE{SC_STATIC_UTILS})
-            if(NOT $<TARGET_PROPERTY:${_lib},TYPE> STREQUAL "STATIC_LIBRARY")
+            get_property(_lib_type TARGET ${_lib} PROPERTY TYPE)
+            if(NOT _lib_type STREQUAL "STATIC_LIBRARY")
                message(SEND_ERROR "SC_ADDEXEC usage error - expected STATIC LINK_LIBRARIES targets (${_lib})")
            endif()
        endif()
-        target_link_libraries(${execname} ${_lib})
+        # Executables consume their dependencies but do not publish an
+        # interface to downstream targets.
+        target_link_libraries(${execname} PRIVATE ${_lib})
    endforeach()
+    target_link_libraries(${execname} PRIVATE ${${_arg_prefix}_LINK_LIBRARIES})
  endif()

  if(NOT ${_arg_prefix}_NO_INSTALL AND NOT ${_arg_prefix}_TESTABLE)
@@ -37,7 +45,7 @@ endmacro()
 macro(SC_ADDLIB _addlib_target)
  set(_addlib_opts SHARED STATIC NO_INSTALL TESTABLE)
  set(_addlib_multikw SOURCES LINK_LIBRARIES)
-  string(TOUPPER "SC_ADDLIB_${libname}_ARG" _arg_prefix)
+  string(TOUPPER "SC_ADDLIB_${_addlib_target}_ARG" _arg_prefix)
  cmake_parse_arguments(${_arg_prefix} "${_addlib_opts}" "" "${_addlib_multikw}" ${ARGN})

  if(NOT DEFINED ${_arg_prefix}_SOURCES)
@@ -64,20 +72,25 @@ macro(SC_ADDLIB _addlib_target)
  if(DEFINED ${_arg_prefix}_LINK_LIBRARIES)
    foreach(_lib ${${_arg_prefix}_LINK_LIBRARIES})
        if(${_arg_prefix}_STATIC AND TARGET ${_lib})
-	  get_property(_libtype TARGET ${_lib} PROPERTY TYPE)
-	  if(NOT ${_libtype} STREQUAL "STATIC_LIBRARY")
-	      message(SEND_ERROR "SC_ADDLIB usage error - expected (static) LINK_LIBRARIES targets (${_lib})")
+          get_property(_libtype TARGET ${_lib} PROPERTY TYPE)
+          if(NOT ${_libtype} STREQUAL "STATIC_LIBRARY")
+            message(SEND_ERROR "SC_ADDLIB usage error - expected (static) LINK_LIBRARIES targets (${_lib})")
            endif()
        endif()
-        target_link_libraries(${_addlib_target} ${_lib})
+        # Schema libraries are consumed directly by generated test programs.
+        # Publish their link requirements explicitly; the legacy unscoped
+        # signature does not reliably provide a transitive interface with
+        # current CMake versions.
+        target_link_libraries(${_addlib_target} PUBLIC ${_lib})
    endforeach()
+    target_link_libraries(${_addlib_target} ${_lib})
  endif()

  if(NOT ${_arg_prefix}_NO_INSTALL AND NOT ${_arg_prefix}_TESTABLE)
    install(TARGETS ${_addlib_target}
      RUNTIME DESTINATION ${BIN_DIR}
      LIBRARY DESTINATION ${LIB_DIR}
-      ARCHIVE DESTINATION ${LIB_DIR}	
+      ARCHIVE DESTINATION ${LIB_DIR}
    )
  endif()
 endmacro()
@@ -88,4 +101,3 @@ endmacro()
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -35,6 +35,7 @@ extern "C" {
 #endif
 }

+#include <algorithm>
 #include <string>
 #include <sstream>
 #include <iomanip>
@@ -50,6 +51,35 @@ using std::ofstream;
 using std::cerr;
 using std::cout;

+static unsigned long entityChunkSize = 256;
+static unsigned long typeChunkSize = 256;
+
+static bool
+parseChunkSizes( const char * value )
+{
+    if( !value || !value[0] ) {
+        return false;
+    }
+    char * end = 0;
+    const unsigned long entities = strtoul( value, &end, 10 );
+    if( !end || entities == 0 ) {
+        return false;
+    }
+    unsigned long types = entities;
+    if( *end == ':' ) {
+        char * typeEnd = 0;
+        types = strtoul( end + 1, &typeEnd, 10 );
+        if( !end[1] || !typeEnd || *typeEnd || types == 0 ) {
+            return false;
+        }
+    } else if( *end ) {
+        return false;
+    }
+    entityChunkSize = entities;
+    typeChunkSize = types;
+    return true;
+}
+
 /** \return true for types that exp2cxx won't generate code for */
 bool notGenerated( const Type t ) {
    switch( TYPEget_body( t )->type ) {
@@ -186,20 +216,34 @@ void writeLists( const char * schemaName, stringstream & eh, stringstream & ei,
    cmLists << "# targets, logic, etc are within a set of macros shared by all schemas" << endl;
    cmLists << "include(${SC_CMAKE_DIR}/SC_CXX_schema_macros.cmake)" << endl;

-    // * 2 for headers, + 10 other files
-    cmLists << "set(" << shortName << "_file_count " << ( ( ecount + tcount ) * 2 ) + 10 << ")" << endl << endl;
+    const int entityChunks = std::max( 1, ( ecount + static_cast<int>( entityChunkSize ) - 1 ) / static_cast<int>( entityChunkSize ) );
+    const int typeChunks = std::max( 1, ( tcount + static_cast<int>( typeChunkSize ) - 1 ) / static_cast<int>( typeChunkSize ) );
+    cmLists << "if(SC_EXP2CXX_LATE_BOUND)" << endl;
+    cmLists << "  set(" << shortName << "_file_count 10)" << endl;
+    cmLists << "else()" << endl;
+    cmLists << "  set(" << shortName << "_file_count " <<
+        ( ecount + tcount ) * 2 + entityChunks + typeChunks + 14 << ")" << endl;
+    cmLists << "endif()" << endl << endl;


    cmLists << "PROJECT(" << shortName << ")" << endl;
    cmLists << "# list headers so they can be installed - entity, type, misc" << endl;

-    cmLists << "set(" << shortName << "_entity_hdrs" << endl;
+    cmLists << "if(SC_EXP2CXX_LATE_BOUND)" << endl;
+    cmLists << "  set(" << shortName << "_entity_hdrs)" << endl;
+    cmLists << "else()" << endl;
+    cmLists << "  set(" << shortName << "_entity_hdrs" << endl;
    cmLists << eh.str();
-    cmLists << "   )" << endl << endl;
+    cmLists << "  )" << endl;
+    cmLists << "endif()" << endl << endl;

-    cmLists << "set(" << shortName << "_type_hdrs" << endl;
+    cmLists << "if(SC_EXP2CXX_LATE_BOUND)" << endl;
+    cmLists << "  set(" << shortName << "_type_hdrs)" << endl;
+    cmLists << "else()" << endl;
+    cmLists << "  set(" << shortName << "_type_hdrs" << endl;
    cmLists << th.str();
-    cmLists << "   )" << endl << endl;
+    cmLists << "  )" << endl;
+    cmLists << "endif()" << endl << endl;

    cmLists << "set(" << shortName << "_misc_hdrs" << endl;
    cmLists << "     Sdaiclasses.h   schema.h" << endl;
@@ -224,11 +268,26 @@ void writeLists( const char * schemaName, stringstream & eh, stringstream & ei,

    cmLists << "# unity build: #include small .cc files to reduce the number" << endl;
    cmLists << "# of translation units that must be compiled" << endl;
-    cmLists << "if(SC_UNITY_BUILD)" << endl << "  # turns off include statements within type and entity .cc's - the unity T.U.'s include a unity header" << endl;
-    cmLists << "  add_definitions( -DSC_SDAI_UNITY_BUILD)" << endl;
-    cmLists << "  set(" << shortName << "_entity_impls Sdai" << schema_upper << "_unity_entities.cc)" << endl;
-    cmLists << "  set(" << shortName << "_type_impls Sdai" << schema_upper << "_unity_types.cc)" << endl;
-    cmLists << "else(SC_UNITY_BUILD)" << endl;
+    cmLists << "if(SC_EXP2CXX_LATE_BOUND)" << endl;
+    cmLists << "  set(" << shortName << "_unity_build FALSE)" << endl;
+    cmLists << "  set(" << shortName << "_entity_impls)" << endl;
+    cmLists << "  set(" << shortName << "_type_impls)" << endl;
+    cmLists << "elseif(SC_UNITY_BUILD)" << endl;
+    cmLists << "  # bounded compact chunks; definitions are target-local" << endl;
+    cmLists << "  set(" << shortName << "_unity_build TRUE)" << endl;
+    cmLists << "  set(" << shortName << "_entity_impls" << endl;
+    for( int chunk = 1; chunk <= entityChunks; ++chunk ) {
+        cmLists << "    Sdai" << schema_upper << "_unity_entities_" <<
+            std::setfill( '0' ) << std::setw( 4 ) << chunk << ".cc" << endl;
+    }
+    cmLists << "  )" << endl;
+    cmLists << "  set(" << shortName << "_type_impls" << endl;
+    for( int chunk = 1; chunk <= typeChunks; ++chunk ) {
+        cmLists << "    Sdai" << schema_upper << "_unity_types_" <<
+            std::setfill( '0' ) << std::setw( 4 ) << chunk << ".cc" << endl;
+    }
+    cmLists << "  )" << endl;
+    cmLists << "else()" << endl;
    cmLists << "  set(" << shortName << "_entity_impls" << endl;
    cmLists << ei.str();
    cmLists << "   )" << endl << endl;
@@ -236,12 +295,13 @@ void writeLists( const char * schemaName, stringstream & eh, stringstream & ei,
    cmLists << "  set(" << shortName << "_type_impls" << endl;
    cmLists << ti.str();
    cmLists << "   )" << endl;
-    cmLists << "endif(SC_UNITY_BUILD)" << endl << endl;
+    cmLists << "endif()" << endl << endl;

    cmLists << "set( " << shortName << "_misc_impls" << endl;
    cmLists << "     SdaiAll.cc    compstructs.cc    schema.cc" << endl;
    cmLists << "     Sdai" << schema_upper << ".cc" << endl;
-    cmLists << "     Sdai" << schema_upper << ".init.cc   )" << endl << endl;
+    cmLists << "     Sdai" << schema_upper << ".init.cc" << endl;
+    cmLists << "     Sdai" << schema_upper << ".sources.cmake   )" << endl << endl;

    cmLists << "set(schema_target_files ${" << shortName << "_entity_impls} " << "${" << shortName << "_type_impls} " << "${" << shortName << "_misc_impls})" << endl;
    cmLists << "SCHEMA_TARGETS(\"" << input_filename << "\" \"" << schemaName << "\"" << endl;
@@ -330,14 +390,18 @@ int main( int argc, char ** argv ) {
    DictionaryEntry de;
    /* copied from fedex.c */
    Express model;
-    if( ( argc != 2 ) || ( strlen( argv[1] ) < 1 ) ) {
-        fprintf( stderr, "\nUsage: %s file.exp\nOutput: a CMakeLists.txt to build the schema,", argv[0] );
+    if( ( argc != 2 && argc != 3 ) || ( strlen( argv[1] ) < 1 ) ) {
+        fprintf( stderr, "\nUsage: %s file.exp [entity-chunk-size[:type-chunk-size]]\nOutput: a CMakeLists.txt to build the schema,", argv[0] );
        fprintf( stderr, " containing file names for entities, types, etc\n" );
        fprintf( stderr, "also prints (to stdout) the absolute path to the directory CMakeLists.txt was created in\n" );
        exit( EXIT_FAILURE );
    }
    EXPRESSprogram_name = argv[0];
    input_filename = argv[1];
+    if( argc == 3 && !parseChunkSizes( argv[2] ) ) {
+        fprintf( stderr, "chunk sizes must be positive integers in N or N:N form\n" );
+        exit( EXIT_FAILURE );
+    }

    EXPRESSinitialize();

@@ -18,6 +18,44 @@ else(NOT DEFINED SC_UNITY_BUILD)
  message( STATUS "Respecting user-defined SC_UNITY_BUILD value of ${SC_UNITY_BUILD}.")
 endif(NOT DEFINED SC_UNITY_BUILD)

+if(NOT DEFINED SC_EXP2CXX_CHUNK_SIZE)
+  set(SC_EXP2CXX_CHUNK_SIZE "64:8" CACHE STRING "Maximum entity:type objects in generated unity translation units")
+endif()
+
+if(NOT DEFINED SC_EXP2CXX_API_VERSION)
+  set(SC_EXP2CXX_API_VERSION "1")
+endif()
+set(SC_EXP2CXX_API_VERSION "${SC_EXP2CXX_API_VERSION}" CACHE STRING "Generated C++ API version (1 or 2)")
+set_property(CACHE SC_EXP2CXX_API_VERSION PROPERTY STRINGS 1 2)
+if(NOT SC_EXP2CXX_API_VERSION MATCHES "^[12]$")
+  message(FATAL_ERROR "SC_EXP2CXX_API_VERSION must be 1 or 2")
+endif()
+
+option(SC_EXP2CXX_LATE_BOUND "Generate descriptor-backed entities without early-bound C++ entity classes" OFF)
+if(SC_EXP2CXX_LATE_BOUND AND NOT SC_EXP2CXX_API_VERSION STREQUAL "2")
+  message(FATAL_ERROR "SC_EXP2CXX_LATE_BOUND requires SC_EXP2CXX_API_VERSION=2")
+endif()
+
+option(SC_EXP2CXX_COMPAT_NAMES "Retain generated entity aliases in late-bound output" OFF)
+if(SC_EXP2CXX_COMPAT_NAMES AND NOT SC_EXP2CXX_LATE_BOUND)
+  message(FATAL_ERROR "SC_EXP2CXX_COMPAT_NAMES requires SC_EXP2CXX_LATE_BOUND=ON")
+endif()
+
+if(NOT DEFINED SC_EXP2CXX_METADATA)
+  set(SC_EXP2CXX_METADATA "full")
+endif()
+set(SC_EXP2CXX_METADATA "${SC_EXP2CXX_METADATA}" CACHE STRING
+  "Generated schema metadata profile (full or structural)")
+set_property(CACHE SC_EXP2CXX_METADATA PROPERTY STRINGS full structural)
+if(NOT SC_EXP2CXX_METADATA MATCHES "^(full|structural)$")
+  message(FATAL_ERROR "SC_EXP2CXX_METADATA must be full or structural")
+endif()
+if(SC_EXP2CXX_METADATA STREQUAL "structural" AND
+   NOT SC_EXP2CXX_LATE_BOUND)
+  message(FATAL_ERROR
+    "SC_EXP2CXX_METADATA=structural requires SC_EXP2CXX_LATE_BOUND=ON")
+endif()
+

 # --- variables ---
 # SC_ROOT: SC root dir
@@ -82,7 +120,7 @@ endif(WIN32)
 # SCHEMA_FILE - path to the schema
 # TODO should we have a result variable to return schema name(s) found?
 macro(SCHEMA_CMLIST SCHEMA_FILE)
-  execute_process(COMMAND ${SCANNER_OUT_DIR}/schema_scanner ${SCHEMA_FILE}
+  execute_process(COMMAND ${SCANNER_OUT_DIR}/schema_scanner ${SCHEMA_FILE} ${SC_EXP2CXX_CHUNK_SIZE}
                   WORKING_DIRECTORY ${SC_BINARY_DIR}/schemas
                   RESULT_VARIABLE _ss_stat
                   OUTPUT_VARIABLE _ss_out
@@ -97,7 +135,16 @@ macro(SCHEMA_CMLIST SCHEMA_FILE)
  string(STRIP "${_ss_out}" _ss_stripped)
  string(REGEX REPLACE "\\\n" ";" _list ${_ss_stripped})
  foreach(_dir ${_list})
-    add_subdirectory(${_dir} ${_dir}) #specify source and binary dirs as the same
+    get_property(_already_added GLOBAL PROPERTY _SC_SCHEMA_DIRS)
+    list(FIND _already_added "${_dir}" _idx)
+    if(${_idx} EQUAL -1)
+       set_property(GLOBAL APPEND PROPERTY _SC_SCHEMA_DIRS "${_dir}")
+       # Keep generated targets under the top-level binary tree.  Passing the
+       # absolute generated-source path as both arguments creates absolute
+       # make target names with newer CMake.
+       get_filename_component(_schema_dir_name "${_dir}" NAME)
+       add_subdirectory("${_dir}" "${SC_BINARY_DIR}/schema-targets/${_schema_dir_name}")
+    endif()
  endforeach(_dir ${_ss_out})
  # configure_file forces cmake to run again if the schema has been modified
  #if multiple schemas in one file, _schema is the last one printed.
@@ -9,7 +9,7 @@ set(CTEST_INITIAL_CACHE "
 SITE:STRING=${CTEST_SITE}
 BUILDNAME:STRING=${CTEST_BUILD_NAME}
 SC_ENABLE_TESTING:BOOL=ON
-SC_BUILD_TYPE:STRING=Debug
+CMAKE_BUILD_TYPE:STRING=Debug
 ")


@@ -0,0 +1,62 @@
+# AP242 TREAT Schema File
+
+This directory contains an altered version of the AP242 (ISO 10303-242) schema.
+
+It is corrected to avoid the non-standard parsing requirement of the original
+by using explicit TREAT expression for type narrowing
+
+## The Difference
+
+Both files are identical except for a single line at line 34149 in the `styled_item` entity WHERE rule WR3:
+
+**Original (242_mim_lf.exp)**:
+```express
+QUERY(it <* item | ...)
+```
+
+**TREAT version (242_mim_lf_treat.exp)**:
+```express
+QUERY(it <* TREAT(item AS set_representation_item) | ...)
+```
+
+### Historical Context
+The original AP242 schema contains a WHERE rule that:
+1. Checks if `item` (a SELECT type) is a `SET_REPRESENTATION_ITEM`
+2. Then tries to iterate over `item` in a QUERY expression
+
+This pattern requires implicit type narrowing, which is not part of the ISO 10303-11 standard.
+
+### STEPcode's Solution
+STEPcode implements **flow-sensitive type narrowing** as an extension:
+- Recognizes TYPEOF guard patterns like `'Type' IN TYPEOF(var)` in AND expressions
+- Automatically narrows the type for subsequent uses
+- Makes the original schema parse successfully
+
+### Standards-Compliant Alternative
+The TREAT version uses the ISO 10303-11 TREAT expression:
+- `TREAT(item AS set_representation_item)` explicitly narrows the type
+- No implicit narrowing needed
+- Works in any compliant EXPRESS parser
+
+## Testing
+
+Both versions parse successfully and produce identical output:
+
+```bash
+# Run comparison test
+./test/compare_ap242_versions.sh
+```
+
+Expected output:
+```
+✓ Both versions parse successfully
+✓ Both versions generate the same number of files
+```
+
+For detailed comparison, see `doc/ap242-comparison.md`.
+
+## Related Documentation
+
+- `doc/ap242-comparison.md` - Detailed comparison and analysis
+- `doc/express-type-unwrapping.md` - TREAT and narrowing documentation
+- `src/express/test/README_AP242_BASELINE.md` - Historical PE056 error info
@@ -0,0 +1,165 @@
+# AP242 Schema Comparison: Flow-Sensitive Narrowing vs TREAT Expression
+
+## Overview
+
+This document compares two versions of the AP242 schema to demonstrate the difference between STEPcode's non-standard flow-sensitive narrowing extension and the ISO 10303-11 compliant TREAT expression.
+
+## Schema Versions
+
+### 1. Original Version (`242_mim_lf.exp`)
+- **Status**: Uses implicit flow-sensitive narrowing (non-standard extension)
+- **Location**: `data/ap242/242_mim_lf.exp`
+- **Size**: 54,756 lines
+- **Problematic code**: Line 34149 in `styled_item` entity, WR3 WHERE rule
+
+### 2. TREAT Version (`242_mim_lf_treat.exp`)
+- **Status**: Standards-compliant using TREAT expression
+- **Location**: `data/ap242/242_mim_lf_treat.exp`  
+- **Size**: 54,756 lines
+- **Fix applied**: Line 34149 - explicit TREAT expression
+
+## The Problem
+
+In the `styled_item` entity at line ~34148, the WHERE rule WR3 contains:
+
+```express
+WR3: ('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.MAPPED_ITEM' IN TYPEOF(item)) OR
+     ('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.GEOMETRIC_REPRESENTATION_ITEM' IN TYPEOF(item)) OR
+     (('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.SET_REPRESENTATION_ITEM' IN TYPEOF(item)) AND
+      (SIZEOF(QUERY(it <* item | ...)) = 0));
+```
+
+### Issue
+- `item` is of type `styled_item_target`, which is a SELECT type
+- The SELECT contains `set_representation_item` (which is an aggregate type)
+- The code checks `'SET_REPRESENTATION_ITEM' IN TYPEOF(item)` (a TYPEOF guard)
+- Then tries to iterate over `item` in a QUERY: `QUERY(it <* item | ...)`
+
+### Why This Was Problematic
+According to strict ISO 10303-11 standards, you cannot iterate over a SELECT type directly in a QUERY expression, even if there's a preceding TYPEOF guard. The guard and the QUERY are separate expressions in an AND clause.
+
+## The Solutions
+
+### Solution 1: Flow-Sensitive Narrowing (Non-Standard Extension)
+
+STEPcode implements a **flow-sensitive type narrowing** extension that:
+1. Recognizes the pattern `'TypeName' IN TYPEOF(var)` in AND expressions
+2. Automatically narrows the type of `var` to `TypeName` for subsequent expressions in the AND
+3. Allows `QUERY(it <* item | ...)` to work because `item` is implicitly narrowed to `set_representation_item`
+
+**Code (original, line 34149)**:
+```express
+QUERY(it <* item | ...)
+```
+
+**How it works**:
+- The AND expression LHS has the guard: `'SET_REPRESENTATION_ITEM' IN TYPEOF(item)`
+- The RHS has the QUERY: `SIZEOF(QUERY(it <* item | ...)) = 0`
+- STEPcode's narrowing recognizes the pattern and narrows `item` to `set_representation_item`
+- The QUERY can now iterate over the narrowed type
+
+### Solution 2: TREAT Expression (Standards-Compliant)
+
+The ISO 10303-11 standard provides the TREAT expression for explicit type narrowing:
+
+**Code (TREAT version, line 34149)**:
+```express
+QUERY(it <* TREAT(item AS set_representation_item) | ...)
+```
+
+**How it works**:
+- `TREAT(item AS set_representation_item)` explicitly narrows the SELECT type to the member type
+- The QUERY can iterate over the result of TREAT, which is guaranteed to be `set_representation_item`
+- No implicit narrowing needed - the intent is explicit in the code
+
+## The Exact Difference
+
+```diff
+--- data/ap242/242_mim_lf.exp
+++ data/ap242/242_mim_lf_treat.exp
+@@ -34146,7 +34146,7 @@
+        ('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.GEOMETRIC_REPRESENTATION_ITEM' IN TYPEOF(item)) OR
+        (('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.SET_REPRESENTATION_ITEM' IN TYPEOF(item)) AND
+         (SIZEOF(QUERY(it
+-                      <* item
+                      <* TREAT(item AS set_representation_item)
+                       | NOT (('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.MAPPED_ITEM' IN TYPEOF(it)) OR
+                              ('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.GEOMETRIC_REPRESENTATION_ITEM' IN
+                               TYPEOF(it))))) =
+```
+
+**Change**: Single line change from `<* item` to `<* TREAT(item AS set_representation_item)`
+
+## Testing Results
+
+### Original Version (with Flow-Sensitive Narrowing)
+```bash
+./build/bin/exp2cxx data/ap242/242_mim_lf.exp /tmp/ap242_original_test
+```
+**Result**: ✅ Parses successfully, generates 5,626 C++ files
+
+### TREAT Version (Standards-Compliant)
+```bash
+./build/bin/exp2cxx data/ap242/242_mim_lf_treat.exp /tmp/ap242_treat_test
+```
+**Result**: ✅ Parses successfully, generates 5,626 C++ files
+
+### Output Comparison
+Both versions generate identical output:
+- Same number of entities
+- Same entity relationships
+- Same multiple inheritance warnings
+- Identical "Finished writing files" status
+
+## Verification
+
+To verify both versions produce consistent output:
+
+```bash
+# Parse original version
+mkdir -p /tmp/ap242_original
+./build/bin/exp2cxx data/ap242/242_mim_lf.exp /tmp/ap242_original
+
+# Parse TREAT version  
+mkdir -p /tmp/ap242_treat
+./build/bin/exp2cxx data/ap242/242_mim_lf_treat.exp /tmp/ap242_treat
+
+# Compare generated headers (should be identical except for file references)
+diff /tmp/ap242_original/SdaiAP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.h \
+     /tmp/ap242_treat/SdaiAP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF.h
+```
+
+## Implications
+
+### For STEPcode Users
+- **Current**: Both versions work due to flow-sensitive narrowing extension
+- **Future**: TREAT version is more portable if other EXPRESS parsers are used
+- **Recommended**: Use TREAT for new schemas to ensure standards compliance
+
+### For STEPcode Development
+- Flow-sensitive narrowing is a valuable usability extension
+- TREAT expression provides standards-compliant alternative
+- Both should continue to be supported for compatibility
+
+### For Standards Compliance
+- Original AP242 schema uses pattern that requires extension
+- TREAT version is fully ISO 10303-11 compliant
+- TREAT makes intent explicit and improves code clarity
+
+## Related Documentation
+
+- `doc/express-type-unwrapping.md` - Full documentation of TREAT and narrowing features
+- `src/express/test/README_AP242_BASELINE.md` - Historical PE056 error documentation
+- Test schemas:
+  - `test/unitary_schemas/flow_narrowing_test.exp` - Flow-sensitive narrowing examples
+  - `test/unitary_schemas/minimal_treat_test.exp` - TREAT expression examples
+
+## Conclusion
+
+This comparison demonstrates:
+1. ✅ STEPcode's flow-sensitive narrowing successfully handles the original AP242 schema
+2. ✅ TREAT expression provides the standards-compliant alternative
+3. ✅ Both approaches produce identical, correct output
+4. ✅ The single-line change makes the code more explicit and portable
+
+The availability of both approaches gives users flexibility while maintaining standards compliance when needed.
@@ -0,0 +1,251 @@
+# AP242 API v2 Output Benchmarks
+
+This file records comparable measurements for the staged API v2 output
+work.  It is intended to make changes in generated output cost visible in
+the commits which introduce them.
+
+## Method
+
+The measurements were made on 2026-08-02 with GCC 13.3.0 and C++11.
+
+The schema under test was BRL-CAD's `ap242e4.exp` conversion schema.
+The real exchange-file workload was the NIST STC 09 ASME AP242 edition
+4 sample, `nist_stc_09_asme1_ap242-e4.stp`.
+
+The generator used `--late-bound`, the default 64-entity and 8-type chunk
+limits, and a release STEPcode build.  Compilation used `-O2 -fPIC` and two
+concurrent compiler processes.  Generated-output counts include `.cc`, `.h`,
+and `.cmake` files through directory depth two.  The baseline is commit
+`fa2758c5` before recommendations 1--4.
+
+## Results
+
+| Measurement | Baseline | Recommendations 1--4 | Change |
+|---|---:|---:|---:|
+| Generated files | 5,719 | 905 | -84.2% |
+| Generated lines | 254,220 | 123,552 | -51.4% |
+| Generated bytes | 13,942,523 | 9,804,680 | -29.7% |
+| Entity leaf files | 4,814 | 0 | -100.0% |
+| Generation wall time | 2.74 s | 0.56 s | -79.6% |
+| Generation peak RSS | 109,024 KiB | 109,280 KiB | +0.2% |
+| Compile/link wall time | 157.68 s | 37.02 s | -76.5% |
+| Compile/link user time | 277.75 s | 66.32 s | -76.1% |
+| Compile/link peak RSS | 593,320 KiB | 199,156 KiB | -66.4% |
+| Schema shared library | 9,956,640 B | 7,716,096 B | -22.5% |
+| ELF relocations | 28,843 | 39,719 | +37.7% |
+| Function symbols | 15,641 | 13,542 | -13.4% |
+| Read/write wall time | 0.26 s | 0.25 s | -3.8% |
+| Read/write peak RSS | 88,732 KiB | 85,040 KiB | -4.2% |
+
+The relocation increase is caused by the stable module-ID tables referring
+to descriptor slots.  It is recorded here because the packed schema image
+stage is expected to remove most of that cost.
+
+## Recommendations 1--4
+
+This stage adds stable entity, type, and attribute IDs through `SchemaModule`,
+makes compatibility entity names opt-in for late-bound output, moves schema
+rules and complex-entity support to runtime-consumed tables, and writes late
+entity metadata directly to bounded chunks instead of creating 4,814 leaf
+files.
+
+The real AP242 exchange-file check created and validated 10,609 instances
+with zero errors and zero warnings.  Its 949,685-byte rewritten Part 21 file
+matched the baseline apart from the expected `FILE_NAME` timestamp.
+
+## Recommendation 5
+
+This stage resolves each late-bound entity's flattened attribute layout once
+after schema initialization.  Instance construction then follows descriptor
+and index records directly instead of recursively walking supertypes and
+repeating attribute-name searches.  The cache is external to
+`EntityDescriptor`, so its object layout and the API v1 ABI are unchanged.
+
+The construction benchmark uses the 1,531 `DIRECTION` instances in the real
+exchange file and repeats that population 1,000 times.  This isolates the
+work changed by this stage while retaining a type and frequency from the
+AP242 workload.  Results are the median of three runs.
+
+| Measurement | Recommendations 1--4 | Recommendation 5 | Change |
+|---|---:|---:|---:|
+| 1,531,000 entity constructions | 0.84 s | 0.63 s | -25.0% |
+| Construction user time | 0.82 s | 0.61 s | -25.6% |
+| Construction peak RSS | 68,956 KiB | 69,600 KiB | +0.9% |
+| 20 full read/write runs | 4.90 s | 4.91 s | no measurable change |
+| Full read/write peak RSS | 85,164 KiB | 85,732 KiB | +0.7% |
+| `libstepcore` size | 640,936 B | 651,312 B | +1.6% |
+
+The complete exchange-file check still created and validated 10,609
+instances with zero errors and zero warnings.  Its rewritten file remained
+949,685 bytes and differed from the previous stage only in the expected
+`FILE_NAME` timestamp.  Generated schema file counts, source size, and the
+schema shared library are unchanged because this is a shared-runtime change.
+
+## Recommendation 6
+
+This stage replaces the generated `SchemaModuleSlot` pointer arrays with a
+16-byte, relocation-free `SchemaModuleImage`.  Shared initialization helpers
+capture descriptor pointers in stable generated-ID order and transfer those
+vectors to `SchemaModule` after initialization.  The older slot-based entry
+point remains available for existing generated API v2 code.
+
+Source and binary measurements compare recommendation 5 with the packed
+image.  Compile times use matching clean CMake builds with two compiler
+processes.  Read/write times are medians from paired 20-run batches.
+
+| Measurement | Recommendation 5 | Recommendation 6 | Change |
+|---|---:|---:|---:|
+| Generated files | 905 | 905 | unchanged |
+| Generated lines | 123,552 | 117,046 | -5.3% |
+| Generated bytes | 9,804,680 | 9,060,249 | -7.6% |
+| Schema module source | 808,907 B | 64,367 B | -92.0% |
+| Schema module source lines | 7,280 | 773 | -89.4% |
+| Compile/link wall time | 41.38 s | 41.49 s | no measurable change |
+| Compile/link peak RSS | 208,312 KiB | 208,188 KiB | -0.1% |
+| Schema shared library | 7,728,384 B | 7,470,304 B | -3.3% |
+| ELF relocations | 39,719 | 33,221 | -16.4% |
+| 20 full read/write runs | 5.10 s | 5.07 s | -0.6% |
+| Full read/write peak RSS | 85,736 KiB | 85,572 KiB | -0.2% |
+| `libstepcore` size | 651,312 B | 661,088 B | +1.5% |
+
+The image removes 6,498 per-descriptor pointer relocations.  The shared
+runtime grows by 9,776 bytes once, while each AP242 schema library is 258,080
+bytes smaller.  Generated API v1 output and the conventional public entity
+classes remain unchanged.
+
+The complete exchange-file check again created and validated 10,609
+instances with zero errors and zero warnings.  Its 949,685-byte rewrite
+differed from recommendation 5 only in the expected `FILE_NAME` timestamp.
+
+## Recommendation 7
+
+This stage replaces the remaining generated descriptor procedures with one
+bounded, offset-based schema image.  The shared loader validates every array,
+string, range, descriptor reference, schema binding, and complex-entity tree
+before it changes the registry.  It then constructs the descriptor graph with
+an explicit per-load context; the process-global capture path remains only for
+older generated API v2 code.  Complex-entity metadata uses the same packed
+representation and validation model.
+
+Source and binary measurements compare recommendation 6 with the complete
+descriptor image.  Compile times use clean CMake builds with two compiler
+processes.  Read/write times use matching 20-run batches.
+
+| Measurement | Recommendation 6 | Recommendation 7 | Change |
+|---|---:|---:|---:|
+| Generated files | 905 | 865 | -4.4% |
+| Generated lines | 117,046 | 86,400 | -26.2% |
+| Generated bytes | 9,060,249 | 4,865,657 | -46.3% |
+| Entity initialization chunks | 38 | 0 | -100.0% |
+| Compile/link wall time | 41.49 s | 18.71 s | -54.9% |
+| Compile/link peak RSS | 208,188 KiB | 208,528 KiB | +0.2% |
+| Schema shared library | 7,470,304 B | 3,503,352 B | -53.1% |
+| ELF relocations | 33,221 | 9,620 | -71.0% |
+| 20 full read/write runs | 5.07 s | 4.97 s | -2.0% |
+| Full read/write peak RSS | 85,572 KiB | 82,916 KiB | -3.1% |
+
+The image removes the 2,407 generated entity initialization functions and
+23,601 additional relocations.  The generated schema library is 3,966,952
+bytes smaller, while its existing typed SELECT and enumeration factories
+remain available for this transitional stage.
+
+The complete exchange-file check created and validated 10,609 instances with
+zero errors and zero warnings.  Its 949,685-byte rewrite retained the same
+semantic result as recommendation 6.
+
+## Recommendations 8 and 9
+
+This stage makes the compact late-bound output independent of generated type
+classes.  Shared descriptor-driven implementations now construct SELECT,
+enumeration, and aggregate values, including nested values and BOOLEAN or
+LOGICAL aliases.  Enumeration elements and renamed USE or REFERENCE items are
+retained in the packed image.  The conventional early-bound API v1 and API v2
+paths still emit their schema-specific type classes.
+
+The generated schema header is now a dependency-bounded consumer interface.
+It contains stable entity, type, and attribute IDs plus `SchemaModule` lookup
+functions, and includes only `schemaModule.h`.  Runtime and model-construction
+declarations remain in the internal `schema.h` umbrella.
+
+| Measurement | Recommendation 7 | Recommendations 8--9 | Change |
+|---|---:|---:|---:|
+| Generated files | 865 | 10 | -98.8% |
+| Generated lines | 86,400 | 54,839 | -36.5% |
+| Generated bytes | 4,865,657 | 3,303,993 | -32.1% |
+| Type leaf files | 802 | 0 | -100.0% |
+| Type initialization chunks | 51 | 0 | -100.0% |
+| Compile/link wall time | 18.71 s | 1.21 s | -93.5% |
+| Compile/link peak RSS | 208,528 KiB | 126,580 KiB | -39.3% |
+| Schema shared library | 3,503,352 B | 2,178,296 B | -37.8% |
+| ELF relocations | 9,620 | 49 | -99.5% |
+| Exported function symbols | 4,647 | 8 | -99.8% |
+| Public header preprocessed bytes | 2,384,191 | 635,945 | -73.3% |
+| 20 full read/write runs | 4.97 s | 4.91 s | -1.2% |
+| Full read/write peak RSS | 82,916 KiB | 82,304 KiB | -0.7% |
+
+The complete exchange-file check again created and validated 10,609
+instances with zero errors and zero warnings, and wrote the same 949,685-byte
+semantic result.  Runtime unit coverage separately exercises generic SELECT,
+enumeration, aggregate, malformed-image, and packed rename behavior.
+
+## Recommendation 10
+
+This stage adds an opt-in `structural` metadata profile for late-bound API
+version 2.  The default `full` profile is unchanged.  Structural images keep
+the descriptor graph needed to construct, read, write, and inspect entity,
+attribute, type, aggregate, enumeration, SELECT, inverse, and renamed values.
+They omit EXPRESS descriptions, WHERE and UNIQUE rules, schema rule and
+algorithm text, supertype statements, derived expressions, and symbolic
+aggregate-bound text.
+
+The source and library measurements below compare matching fresh output from
+the two profiles.  Compile times use clean CMake builds with one compiler
+process; read/write times use matching 20-run batches.
+
+| Measurement | Full metadata | Structural metadata | Change |
+|---|---:|---:|---:|
+| Generated files | 10 | 10 | unchanged |
+| Generated lines | 54,839 | 29,993 | -45.3% |
+| Generated bytes | 3,304,007 | 1,525,897 | -53.8% |
+| Packed schema source | 2,612,413 B | 834,303 B | -68.1% |
+| Generation wall time | 0.48 s | 0.41 s | -14.6% |
+| Compile/link wall time | 2.08 s | 2.03 s | -2.4% |
+| Compile/link peak RSS | 126,784 KiB | 118,220 KiB | -6.8% |
+| Schema shared library | 2,178,296 B | 720,120 B | -66.9% |
+| ELF relocations | 49 | 49 | unchanged |
+| 20 full read/write runs | 4.76 s | 4.71 s | -1.1% |
+| Full read/write peak RSS | 82,276 KiB | 78,900 KiB | -4.1% |
+
+The structural profile created and validated all 10,609 instances in the
+real exchange file with zero errors and zero warnings.  It wrote the same
+949,685-byte semantic result as the full profile.
+
+## Recommendation 11
+
+This stage writes each generated file to a sibling temporary file and replaces
+the destination only when its content changes.  A compact generated-file
+manifest supports safe cleanup when an option change makes old entity, type,
+or unity files obsolete; files not named by the previous manifest are left
+alone.  The manifest itself is also content-stable.
+
+The deterministic-output audit also found that nonliteral aggregate bounds
+were being read through the integer member of the expression union.  Packed
+images now emit those bounds as expression records, eliminating process-address
+values from generated AP242 source as well as correcting the metadata kind.
+
+| Measurement after identical AP242 generation | Rewrite all | Stable output | Change |
+|---|---:|---:|---:|
+| Changed schema source/header timestamps | 10 of 10 | 0 of 10 | -100.0% |
+| Changed manifest timestamps | n/a | 0 of 1 | stable |
+| Generation wall time | 0.41 s | 0.40 s | no overhead |
+| Following CMake build wall time | 2.01 s | 0.06 s | -97.0% |
+| Following build peak RSS | 118,108 KiB | 18,432 KiB | -84.4% |
+
+The AP242 manifest is 390 bytes.  Switching the focused regression schema
+from early-bound API version 2 to compact late-bound output removes all stale
+entity, type, and unity files and their empty directories while preserving an
+unrelated file in the output directory.
+
+The real exchange-file check still created and validated all 10,609 instances
+with zero errors and zero warnings.  Its rewritten result remained 949,685
+bytes.
@@ -0,0 +1,367 @@
+# EXPRESS Type Unwrapping and Narrowing
+
+## Overview
+
+This document describes the type unwrapping and narrowing features implemented in STEPcode's EXPRESS compiler. These features enable proper type checking and semantic analysis for aggregate types and SELECT type narrowing.
+
+**Note:** Some features described here are extensions beyond the ISO 10303-11 standard and are explicitly marked as such.
+
+## Deep Aggregate Unwrapping
+
+### Background
+
+In EXPRESS, aggregate types (ARRAY, LIST, SET, BAG) can be nested and wrapped in type definitions. For semantic analysis and type checking, the compiler often needs to "unwrap" these layers to access the underlying element type.
+
+### Shallow vs Deep Type Checking
+
+#### Shallow Aggregate Check: `TYPEis_aggregate`
+
+The macro `TYPEis_aggregate(t)` performs a **shallow** check by testing if `t->u.type->body->base` is non-NULL. This indicates the type has a base type, which is characteristic of aggregate types.
+
+```c
+#define TYPEis_aggregate(t) ((t)->u.type->body->base)
+```
+
+**Important:** This is a shallow check and does not follow type definition chains. It returns true if the immediate type structure has a base type.
+
+**Use when:**
+- You need a quick check if a type is directly an aggregate
+- You're working with the immediate type structure
+- Performance is critical and deep unwrapping isn't needed
+
+#### Deep Aggregate Unwrapping: `TYPEget_nonaggregate_base_type`
+
+The function `TYPEget_nonaggregate_base_type(Type t)` performs **deep unwrapping** by iteratively following the chain of aggregate base types until reaching a non-aggregate type.
+
+```express
+TYPE int_list = LIST OF INTEGER;
+TYPE named_int_list = int_list;  -- typedef chain
+TYPE set_of_lists = SET OF named_int_list;
+```
+
+For `set_of_lists`:
+- `TYPEis_aggregate()` → true (immediate check)
+- `TYPEget_nonaggregate_base_type()` → INTEGER (unwraps through SET → LIST → INTEGER)
+
+**Use when:**
+- Comparing element types across different aggregate wrappers
+- Type resolution requires the ultimate element type
+- Semantic checking needs to validate deep type compatibility
+
+### Deep Unwrapping Implementation
+
+```c
+Type TYPEget_nonaggregate_base_type( Type t ) {
+    while( TYPEis_aggregate( t ) ) {
+        t = t->u.type->body->base;
+    }
+    return t;
+}
+```
+
+This function safely handles:
+- Nested aggregates (SET OF LIST OF ...)
+- Type definition chains
+- Mixed aggregate types
+
+### Aggregate Type Comparison: `TYPE_retrieve_aggregate`
+
+For SELECT types containing multiple aggregate members, `TYPE_retrieve_aggregate()` validates that all aggregate members share the same element type.
+
+```express
+TYPE item_a = SET OF INTEGER;
+TYPE item_b = LIST OF INTEGER;
+TYPE my_select = SELECT(item_a, item_b);  -- Valid: both have INTEGER elements
+```
+
+The function:
+1. Iterates through SELECT members
+2. Identifies which are aggregates
+3. Unwraps typedef chains to find element types
+4. Returns common element type or NULL if incompatible
+
+## TREAT Expression Semantics
+
+### ISO 10303-11 Standard Syntax
+
+The TREAT expression is defined in ISO 10303-11 as:
+
+```express
+TREAT(expression AS type_identifier)
+```
+
+**Purpose:** Explicitly narrow a SELECT type to one of its member types.
+
+### STEPcode Implementation
+
+STEPcode implements TREAT as specified in ISO 10303-11 with the following semantics:
+
+#### Type Resolution
+
+1. **Operand Resolution:** The expression being narrowed is resolved first
+   ```c
+   EXPresolve( e->e.op1, s, Type_Dont_Care );
+   operand_type = e->e.op1->return_type;
+   ```
+
+2. **Target Type Lookup:** The target type identifier is resolved via scope lookup
+   ```c
+   target_type = (Type)SCOPEfind( s, e->symbol.name, SCOPE_FIND_TYPE );
+   ```
+
+3. **Type Compatibility:** The implementation validates that narrowing is semantically valid
+   - For SELECT operands: Verifies target is a member type
+   - For other types: Allows permissively (may emit warnings)
+
+4. **Return Type:** The expression's return type becomes the target type
+   ```c
+   return target_type;  /* Not Type_Generic */
+   ```
+
+#### Error Handling
+
+**Clear errors with location information:**
+
+- **Missing operand:** `SYNTAX` error - "TREAT expression missing operand"
+- **Missing target type:** `SYNTAX` error - "TREAT expression missing target type"  
+- **Undefined type:** `UNDEFINED_TYPE` error with the type name
+- **Type mismatch:** Currently permissive (no error, future: may warn)
+
+All errors use `ERRORreport_with_symbol()` which provides:
+- File name and line number
+- Symbol context
+- Descriptive error message
+
+#### Example Usage
+
+```express
+TYPE attachment = SELECT(nail, screw);
+END_TYPE;
+
+FUNCTION get_length(item : attachment) : REAL;
+  LOCAL
+    n : nail;
+  END_LOCAL;
+  
+  IF ('EXAMPLE.NAIL' IN TYPEOF(item)) THEN
+    n := TREAT(item AS nail);  -- Narrows SELECT to nail
+    RETURN n.length;
+  END_IF;
+  
+  RETURN 0.0;
+END_FUNCTION;
+```
+
+### Grammar Integration
+
+The TREAT syntax is integrated into the EXPRESS parser grammar as a unary expression:
+
+```yacc
+unary_expression ::= TOK_TREAT TOK_LEFT_PAREN expression TOK_AS 
+                     TOK_IDENTIFIER TOK_RIGHT_PAREN
+```
+
+Key points:
+- `TOK_TREAT`: Recognized as a keyword
+- Creates unary expression with `OP_TREAT` operator
+- Operand stored in `op1`
+- Target type name stored in `symbol` field
+
+## Flow-Sensitive SELECT Narrowing
+
+**Extension Status:** This is a **non-standard extension** that enhances type safety for SELECT types.
+
+### Background
+
+EXPRESS WHERE clauses often use TYPEOF guards to check SELECT types before accessing member-specific attributes. Flow-sensitive narrowing automatically narrows SELECT types within the scope of such guards.
+
+### Pattern Recognition
+
+The narrowing system recognizes this pattern:
+
+```express
+'TypeName' IN TYPEOF(variable)
+```
+
+When this pattern appears in an AND conjunction, the variable is narrowed to `TypeName` for subsequent expressions in the conjunction.
+
+### Implementation Architecture
+
+#### Refinement Context
+
+A **refinement context** tracks active type narrowings during expression resolution:
+
+```c
+typedef struct RefinementContext_ {
+    Refinement refinements;        /* Linked list of variable → type mappings */
+    struct RefinementContext_ *previous;  /* Stack of contexts */
+} *RefinementContext;
+
+RefinementContext active_refinements = NULL;  /* Thread-local global */
+```
+
+#### Pattern Matching
+
+The function `match_typeof_guard()` identifies guard patterns:
+
+1. Expression is `IN` operator
+2. Left operand is string literal (type name)
+3. Right operand is `TYPEOF(identifier)`
+4. Identifier resolves to a variable
+
+#### Refinement Collection
+
+The function `collect_refinements_from_conjunction()` recursively walks AND expressions:
+
+1. Recursively descends into AND nodes
+2. Matches TYPEOF guard patterns at leaves
+3. Validates narrowing is semantically correct:
+   - Variable must have SELECT type
+   - Target type must be SELECT member (validated via `is_select_member()`)
+4. Returns linked list of valid refinements
+
+#### Application
+
+In `EXPresolve_op_and()`:
+
+```c
+Type EXPresolve_op_and(Expression e, Scope s) {
+    EXPresolve(e->e.op1, s, Type_Dont_Care);  /* Resolve LHS normally */
+    
+    Refinement refs = collect_refinements_from_conjunction(e->e.op1, s);
+    
+    if (refs) {
+        /* Create temporary context */
+        struct RefinementContext_ ctx;
+        ctx.refinements = refs;
+        ctx.previous = active_refinements;
+        active_refinements = &ctx;
+        
+        EXPresolve(e->e.op2, s, Type_Dont_Care);  /* Resolve RHS with narrowing */
+        
+        /* Restore previous context */
+        active_refinements = ctx.previous;
+        free_refinements(refs);
+    } else {
+        EXPresolve(e->e.op2, s, Type_Dont_Care);
+    }
+    
+    return Type_Logical;
+}
+```
+
+### Behavior Scope
+
+**What is narrowed:**
+- Variables with SELECT type
+- Within RHS of AND expressions
+- Where LHS contains TYPEOF guard
+
+**What is NOT narrowed:**
+- OR expressions (conservative - doesn't extract from disjunction)
+- NOT expressions (conservative - doesn't extract from negation)
+- Other boolean operators
+- Variables not guarded by TYPEOF
+
+**Rationale:** Conservative approach prevents false narrowing in cases where the guard may not hold.
+
+### Limitations
+
+1. **Single-level context:** Only immediate AND RHS is narrowed, not deeply nested scopes
+2. **No cross-statement narrowing:** Limited to expression-level scope
+3. **AND-only:** Does not propagate through OR/NOT (conservative)
+4. **Pattern-based:** Only recognizes exact `'Type' IN TYPEOF(var)` pattern
+
+### Example
+
+```express
+ENTITY test_entity;
+  item : target;  -- target is SELECT(set_representation_item, simple_int)
+WHERE
+  wr1: ('SCHEMA.SET_REPRESENTATION_ITEM' IN TYPEOF(item)) AND 
+       (SIZEOF(item) > 0);  -- item narrowed to set_representation_item
+END_ENTITY;
+```
+
+Without narrowing, `SIZEOF(item)` would fail (can't take SIZEOF of SELECT). With narrowing, `item` is known to be an aggregate, so `SIZEOF` is valid.
+
+## Memory Management
+
+### Refinement Lifecycle
+
+1. **Collection:** `collect_refinements_from_conjunction()` allocates refinement nodes
+2. **Usage:** Active during RHS expression resolution only
+3. **Cleanup:** `free_refinements()` called after RHS resolution completes
+
+### Context Stack Model
+
+The implementation uses a **stack-based context model** rather than deep copying:
+
+- `RefinementContext` has `previous` pointer forming a stack
+- New contexts pushed onto stack with `active_refinements = &ctx`
+- Restored with `active_refinements = ctx.previous`
+- No deep copying of refinement data
+
+**Memory safety:**
+- Refinement nodes allocated individually
+- Freed immediately after use
+- No dangling pointers (stack-local contexts)
+- No memory leaks (verified by code inspection)
+
+## Testing
+
+### Test Coverage
+
+**TREAT expression tests:**
+- `test/unitary_schemas/minimal_treat_test.exp` - Basic TREAT usage
+- `test/unitary_schemas/test_treat_real.exp` - Nested SELECT types
+- `test/unitary_schemas/treat_expression.exp` - TREAT in WHERE clauses
+
+**Flow-sensitive narrowing tests:**
+- `test/unitary_schemas/flow_narrowing_test.exp` - AND-based narrowing
+- `test/unitary_schemas/select_aggregate_test.exp` - SELECT of aggregates
+
+**Production schema comparison:**
+- `data/ap242/242_mim_lf.exp` - Original AP242 with flow-sensitive narrowing
+- `data/ap242/242_mim_lf_treat.exp` - TREAT-based standards-compliant version
+- `test/compare_ap242_versions.sh` - Automated comparison script
+
+See `doc/ap242-comparison.md` for detailed analysis of the AP242 schema comparison.
+
+### AP242 Compatibility
+
+The implementation is validated against the AP242 schema, ensuring:
+- Large-scale schema parsing succeeds
+- Complex type hierarchies handled correctly
+- Production schema compatibility
+
+**AP242 Schema Versions:**
+- `data/ap242/242_mim_lf.exp` - Original schema using flow-sensitive narrowing extension
+- `data/ap242/242_mim_lf_treat.exp` - Standards-compliant version using TREAT expression
+
+Both versions parse successfully and produce identical output. See `doc/ap242-comparison.md` for detailed analysis.
+
+## Standards Compliance Notes
+
+### ISO 10303-11 Compliance
+
+**Fully compliant:**
+- TREAT expression syntax and semantics
+- Aggregate type definitions
+- SELECT type definitions
+- Standard type resolution rules
+
+**Extensions (non-standard):**
+- Flow-sensitive type narrowing in AND expressions
+- Permissive TREAT type checking (warns vs errors)
+
+### Extension Philosophy
+
+STEPcode's extensions follow these principles:
+
+1. **Conservative:** Only apply when semantically safe
+2. **Permissive:** Prefer warnings over errors where reasonable
+3. **Explicit:** Document extensions clearly
+4. **Compatible:** Don't break standard-compliant schemas
+
+Extensions are designed to enhance usability while maintaining backward compatibility with ISO 10303-11 compliant EXPRESS schemas.
@@ -45,6 +45,11 @@ EXPRESS code into C++ source code.  The C++ source code is generated
 in files in the directory in which exp2cxx was run.  The files are
 named according to the schema names in the input EXPRESS file.

+Generated files are replaced only when their content changes.  exp2cxx records
+the files it owns in `.exp2cxx-manifest`; a later run removes obsolete files
+from that manifest while leaving unrelated files in the output directory
+untouched.
+
 .SH OPTIONS
 .TP
 .B -s|S
@@ -57,6 +62,34 @@ Generates C++ classes for use with CORBA (Orbix).
 .B -l|L
 Prints logging code in the generated C++ classes.
 .TP
+.B -k entity-chunk-size[:type-chunk-size]
+Limits the number of generated schema objects in each deterministic unity
+translation unit.  A single value applies to both entity and type chunks.
+.TP
+.B -V 1|2, --api-version 1|2
+Selects the generated C++ API.  Version 1 is the source-compatible default.
+Version 2 emits compact SELECT classes, table-driven schema initialization, and
+dependency-bounded entity headers backed by shared runtime code.  Version 2
+clients include the individual entity headers they use; schema.h does not
+include every entity class definition.
+.TP
+.B -T, --late-bound
+Selects API version 2 and omits generated early-bound C++ entity classes.
+Entity instances are constructed at runtime from schema descriptors.  This mode
+is intended for conversion and inspection applications which do not require the
+conventional generated entity API.
+.TP
+.B --compat-names
+Retains the generated entity-name aliases in late-bound output.  Normal
+late-bound API v2 output uses schema module IDs instead and omits these aliases.
+.TP
+.B --metadata full|structural
+Selects the generated schema metadata profile.  Full is the default and
+retains EXPRESS descriptions, constraints, and executable schema text.
+Structural is available with late-bound API version 2; it retains the entity,
+attribute, type, aggregate, enumeration, SELECT, inverse, and rename graph
+needed by conversion tools while omitting descriptive and constraint text.
+.TP
 .B -v
 Produces a version description.
 .TP
@@ -161,4 +194,3 @@ appropriate file to download).

 .SH BUGS
 See fedex(1).
-
@@ -31,7 +31,6 @@ set(SC_IS_SUBBUILD TRUE)
 if(NOT DEFINED CMAKE_BUILD_TYPE)
  set(CMAKE_BUILD_TYPE Debug)
 endif(NOT DEFINED CMAKE_BUILD_TYPE)
-set(SC_BUILD_TYPE ${CMAKE_BUILD_TYPE})

 # Path to STEPcode
 set(STEPCODE_BUILD_DIR ${CMAKE_BINARY_DIR}/sc CACHE PATH "STEPcode build subdir")
@@ -4,9 +4,9 @@ ExternalProject_Add( STEPCODE
 		-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
 		-DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
 		-DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}
-		-DSC_BUILD_TYPE=Debug
+		-DCMAKE_BUILD_TYPE=Debug
 		-DSC_BUILD_SCHEMAS=ap203/ap203.exp
-		-DSC_BUILD_STATIC_LIBS=ON
+		-DBUILD_STATIC_LIBS=ON
 		-DSC_PYTHON_GENERATOR=OFF
 		-DSC_INSTALL_PREFIX:PATH=<INSTALL_DIR>
 )
@@ -5,6 +5,7 @@ set(LAZY_HDRS
  p21HeaderSectionReader.h
  lazyDataSectionReader.h
  lazyInstMgr.h
+  lazySupport.h
  lazyTypes.h
  sectionReader.h
  instMgrHelper.h
@@ -24,4 +25,3 @@ install(FILES ${LAZY_HDRS}
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -27,12 +27,9 @@ class SC_LAZYFILE_EXPORT headerSectionReader: public sectionReader {
        }

        virtual ~headerSectionReader() {
-            //FIXME delete each instance?! maybe add to clear, since it iterates over everything already
-            //enum clearHow { rawData, deletePointers }
-            _headerInstances->clear();
+            _headerInstances->clear( true );
 	    delete _headerInstances;
        }
 };

 #endif  //HEADERSECTIONREADER_H
-
@@ -31,7 +31,9 @@ class SC_LAZYFILE_EXPORT mgrNodeHelper: public MgrNodeBase {
            _id = id;
        }
        inline SDAI_Application_instance * GetSTEPentity() {
-            return _lim->loadInstance( _id, true );
+            /* Attribute resolution must not convert a batch-owned cache hit
+             * into a process-lifetime retained instance. */
+            return _lim->loadInstance( _id, true, false );
        }
 };

@@ -58,4 +60,3 @@ class SC_LAZYFILE_EXPORT instMgrAdapter: public InstMgrBase {


 #endif //INSTMGRHELPER_H
-
@@ -25,8 +25,8 @@ struct judyl2KVpair {
 /** A judyL2 array maps JudyKey's to multiple JudyValue's, similar to std::multimap.
 * Internally, this is a judyL array of std::vector< JudyValue >.
 * The first template parameter must be the same size as a void*
- *  \param JudyKey the type of the key, i.e. uint64_t, etc
- *  \param JudyValue the type of the value, i.e. int, pointer-to-object, etc. With judyL2Array, the size of this value can vary.
+ *  \tparam JudyKey the type of the key, i.e. uint64_t, etc
+ *  \tparam JudyValue the type of the value, i.e. int, pointer-to-object, etc. With judyL2Array, the size of this value can vary.
 */
 template< typename JudyKey, typename JudyValue >
 class judyL2Array {
@@ -24,8 +24,8 @@ struct judylKVpair {
 * a JudyValue. Each cell must be set to a non-zero value by the caller.
 *
 * Both template parameters must be the same size as a void*
- *  \param JudyKey the type of the key, i.e. uint64_t, pointer-to-object, etc
- *  \param JudyValue the type of the value
+ *  \tparam JudyKey the type of the key, i.e. uint64_t, pointer-to-object, etc
+ *  \tparam JudyValue the type of the value
 */
 template< typename JudyKey, typename JudyValue >
 class judyLArray {
@@ -159,8 +159,8 @@ class judyLArray {
         * getLastValue() will return the entry before the one that was deleted
         * \sa isEmpty()
         */
-        bool removeEntry( JudyKey * key ) {
-            if( judy_slot( _judyarray, key, _depth * JUDY_key_size ) ) {
+        bool removeEntry( JudyKey key ) {
+            if( judy_slot( _judyarray, reinterpret_cast<const unsigned char *>( &key ), _depth * JUDY_key_size ) ) {
                _lastSlot = ( JudyValue * ) judy_del( _judyarray );
                return true;
            } else {
@@ -25,7 +25,7 @@ struct judys2KVpair {

 /** A judyS2 array maps a set of strings to multiple JudyValue's, similar to std::multimap.
 * Internally, this is a judyS array of std::vector< JudyValue >.
- *  \param JudyValue the type of the value, i.e. int, pointer-to-object, etc.
+ *  \tparam JudyValue the type of the value, i.e. int, pointer-to-object, etc.
 */
 template< typename JudyValue >
 class judyS2Array {
@@ -51,8 +51,8 @@ class judyS2Array {
        explicit judyS2Array( const judyS2Array< JudyValue > & other ): _maxKeyLen( other._maxKeyLen ), _success( other._success ) {
            _judyarray = judy_clone( other._judyarray );
            _buff = new unsigned char[_maxKeyLen];
-            strncpy( _buff, other._buff, _maxKeyLen );
-            _buff[ _maxKeyLen ] = '\0'; //ensure that _buff is null-terminated, since strncpy won't necessarily do so
+            strncpy( reinterpret_cast< char * >( _buff ), reinterpret_cast< const char * >( other._buff ), _maxKeyLen - 1 );
+            _buff[ _maxKeyLen - 1 ] = '\0'; //ensure that _buff is null-terminated
            find( _buff ); //set _lastSlot
        }

@@ -39,8 +39,8 @@ class judySArray {
        explicit judySArray( const judySArray< JudyValue > & other ): _maxKeyLen( other._maxKeyLen ), _success( other._success ) {
            _judyarray = judy_clone( other._judyarray );
            _buff = new unsigned char[_maxKeyLen];
-            strncpy( _buff, other._buff, _maxKeyLen );
-            _buff[ _maxKeyLen ] = '\0'; //ensure that _buff is null-terminated, since strncpy won't necessarily do so
+            strncpy( reinterpret_cast< char * >( _buff ), reinterpret_cast< const char * >( other._buff ), _maxKeyLen - 1 );
+            _buff[ _maxKeyLen - 1 ] = '\0'; //ensure that _buff is null-terminated
            find( _buff ); //set _lastSlot
        }

@@ -1,6 +1,7 @@
 #ifndef LAZYFILEREADER_H
 #define LAZYFILEREADER_H

+#include <atomic>
 #include <vector>
 #include <string>
 #include <cstdlib>
@@ -32,11 +33,14 @@ class SC_LAZYFILE_EXPORT lazyFileReader {
        lazyInstMgr * _parent;
        headerSectionReader * _header;
        std::ifstream _file;
+        std::atomic<bool> _schemaWarningClaimed;
 #ifdef _MSC_VER
 #pragma warning( pop )
 #endif
        fileTypeEnum _fileType;
        fileID _fileID;
+        lazyFileOffset _fileSize;
+        bool _valid;

        void initP21();

@@ -48,6 +52,12 @@ class SC_LAZYFILE_EXPORT lazyFileReader {
        fileID ID() const {
            return _fileID;
        }
+        lazyFileOffset fileSize() const {
+            return _fileSize;
+        }
+        bool valid() const {
+            return _valid;
+        }
        instancesLoaded_t * getHeaderInstances();

        lazyFileReader( std::string fname, lazyInstMgr * i, fileID fid );
@@ -60,8 +70,15 @@ class SC_LAZYFILE_EXPORT lazyFileReader {
            return _parent;
        }

+        /** Return true only to the first caller reporting a FILE_SCHEMA
+         * selection warning for this file.  Instance materialization may
+         * occur concurrently and span multiple DATA sections. */
+        bool claimSchemaWarning() {
+            return !_schemaWarningClaimed.exchange( true,
+                std::memory_order_relaxed );
+        }
+
        bool needKW( const char * kw );
 };

 #endif //LAZYFILEREADER_H
-
@@ -1,13 +1,17 @@
 #ifndef LAZYINSTMGR_H
 #define LAZYINSTMGR_H

+#include <cctype>
 #include <map>
+#include <set>
 #include <string>
+#include <vector>
 #include <assert.h>

 #include "cllazyfile/lazyDataSectionReader.h"
 #include "cllazyfile/lazyFileReader.h"
 #include "cllazyfile/lazyTypes.h"
+#include "cllazyfile/lazySupport.h"

 #include "clstepcore/Registry.h"
 #include "sc_export.h"
@@ -19,6 +23,7 @@

 class Registry;
 class instMgrAdapter;
+class lazyRefs;

 class SC_LAZYFILE_EXPORT lazyInstMgr {
    protected:
@@ -61,15 +66,51 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {

        lazyFileReaderVec_t _files;

+        /** All indexed DATA instance IDs in deterministic file order. */
+        instanceRefs _allInstances;
+
        Registry * _headerRegistry, * _mainRegistry;
+        bool _ownsMainRegistry;
        ErrorDescriptor * _errors;

        unsigned long _lazyInstanceCount, _loadedInstanceCount;
+        uint64_t _cacheHighWater, _cacheHits, _cacheMisses, _materializations, _evictions;
+        uint64_t _activeBatches;
+        uint64_t _residentSourceBytes, _sourceBytesHighWater;
        int _longestTypeNameLen;
        std::string _longestTypeName;

+        std::map<instanceID, size_t> _pinCounts;
+        std::map<instanceID, uint64_t> _instanceSourceBytes;
+        std::map<instanceID, std::vector<std::string> > _instanceComponentTypes;
+        std::map<std::string, std::string> _materializationTypeAliases;
+        std::set<instanceID> _batchOwnedInstances;
+        std::set<instanceID> _permanentlyLoadedInstances;
+        std::set<instanceID> _instancesLoading;
+        std::set<instanceID> _deferredInverseInstances;
+        size_t _batchLoadDepth;
+
+        LazyProgressCallback _progressCallback;
+        LazyCancellationCallback _cancellationCallback;
+        LazyDiagnosticCallback _diagnosticCallback;
+        std::map<std::string, uint64_t> _diagnosticCounts;
+        bool _cancelled;
+
        instMgrAdapter * _ima;

+        friend class LazyInstanceBatch;
+        friend class lazyRefs;
+        void releaseBatch( const std::vector<instanceID> & instances );
+        void resolveDeferredInverses();
+        bool isMaterializing( instanceID id ) const {
+            return _instancesLoading.count( id ) != 0;
+        }
+        void deferInverseResolution( instanceID id ) {
+            _deferredInverseInstances.insert( id );
+        }
+        SDAI_Application_instance * cachedInstance( instanceID id );
+        std::vector<instanceID> dependencyClosure( const std::vector<instanceID> & roots );
+
 #ifdef _MSC_VER
 #pragma warning( pop )
 #endif
@@ -77,13 +118,34 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
    public:
        lazyInstMgr();
        ~lazyInstMgr();
-        void openFile( std::string fname );
+        bool openFile( std::string fname );

        void addLazyInstance( namedLazyInstance inst );
        InstMgrBase * getAdapter() {
            return ( InstMgrBase * ) _ima;
        }

+        /** Register an explicit source-keyword substitution used only when
+         * materializing an SDAI object.  The lazy type index retains the
+         * original Part 21 keyword.  This is intended for known,
+         * attribute-compatible exporter aliases, not arbitrary recovery. */
+        void setMaterializationTypeAlias( std::string source, const std::string & target ) {
+            for( std::string::iterator c = source.begin(); c != source.end(); ++c ) {
+                *c = static_cast<char>( toupper( static_cast<unsigned char>( *c ) ) );
+            }
+            _materializationTypeAliases[source] = target;
+        }
+
+        std::string materializationType( std::string source ) const {
+            std::string key = source;
+            for( std::string::iterator c = key.begin(); c != key.end(); ++c ) {
+                *c = static_cast<char>( toupper( static_cast<unsigned char>( *c ) ) );
+            }
+            std::map<std::string, std::string>::const_iterator alias =
+                _materializationTypeAliases.find( key );
+            return alias == _materializationTypeAliases.end() ? source : alias->second;
+        }
+
        instanceRefs_t * getFwdRefs() {
            return & _fwdInstanceRefs;
        }
@@ -91,19 +153,33 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
        instanceRefs_t * getRevRefs() {
            return & _revInstanceRefs;
        }
+        LazyInstanceIdView instancesByType( std::string type, bool caseSensitive = false );
+        LazyInstanceIdView allInstances() const {
+            return LazyInstanceIdView( &_allInstances );
+        }
+        LazyInstanceIdView forwardReferences( instanceID id );
+        LazyInstanceIdView reverseReferences( instanceID id );
+        /** Copy the exact indexed source record for an instance.  Returns an
+         * empty string when the ID is missing or ambiguous. */
+        std::string sourceRecord( instanceID id );
+        /** Return the Part 21 component keywords of a complex instance in
+         * source order.  Ordinary and unknown instances return an empty
+         * vector. */
+        const std::vector<std::string> & componentTypes( instanceID id ) const;
+
        /// returns a vector containing the instances that match `type`
        instanceTypes_t::cvector * getInstances( std::string type, bool caseSensitive = false ) { /*const*/
            if( !caseSensitive ) {
                std::string::iterator it = type.begin();
                for( ; it != type.end(); ++it ) {
-                    *it = toupper( *it );
+                    *it = static_cast<char>( toupper( static_cast<unsigned char>( *it ) ) );
                }
            }
            return _instanceTypes->find( type.c_str() );
        }
        /// get the number of instances of a certain type
-        unsigned int countInstances( std::string type ) {
-            instanceTypes_t::cvector * v = _instanceTypes->find( type.c_str() );
+        unsigned int countInstances( std::string type, bool caseSensitive = false ) {
+            instanceTypes_t::cvector * v = getInstances( type, caseSensitive );
            if( !v ) {
                return 0;
            }
@@ -123,6 +199,28 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
            return _loadedInstanceCount;
        }

+        LazyCacheStatistics cacheStatistics() const;
+
+        void setProgressCallback( const LazyProgressCallback & callback ) {
+            _progressCallback = callback;
+        }
+        void setCancellationCallback( const LazyCancellationCallback & callback ) {
+            _cancellationCallback = callback;
+        }
+        void setDiagnosticCallback( const LazyDiagnosticCallback & callback ) {
+            _diagnosticCallback = callback;
+        }
+        bool cancelled() const {
+            return _cancelled;
+        }
+        void observeScan( fileID file, lazyFileOffset offset, lazyFileOffset fileSize );
+        void emitDiagnostic( LazyDiagnostic diagnostic );
+        uint64_t diagnosticCount( const std::string & key ) const;
+        const std::map<std::string, uint64_t> & diagnosticCounts() const {
+            return _diagnosticCounts;
+        }
+        void validateReferences();
+
        /// get the number of data sections that have been identified
        unsigned int countDataSections() {
            return _dataSections.size();
@@ -130,7 +228,9 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {

        ///builds the registry using the given initFunct
        const Registry * initRegistry( CF_init initFunct ) {
-            setRegistry( new Registry( initFunct ) );
+            assert( _mainRegistry == 0 );
+            _mainRegistry = new Registry( initFunct );
+            _ownsMainRegistry = true;
            return _mainRegistry;
        }

@@ -138,6 +238,7 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
        void setRegistry( Registry * reg ) {
            assert( _mainRegistry == 0 );
            _mainRegistry = reg;
+            _ownsMainRegistry = false;
        }

        const Registry * getHeaderRegistry() const {
@@ -165,8 +266,12 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
        /** returns a pointer to an instance, loading it if necessary.
         * \param id the instance number to look for
         * \param reSeek if true, reset file position to current position when done. only necessary when loading an instance with dependencies; excessive use will cause a performance hit
+         * \param promoteCached if true, a cached instance requested outside a batch is retained for legacy callers
         */
-        SDAI_Application_instance * loadInstance( instanceID id, bool reSeek = false );
+        SDAI_Application_instance * loadInstance( instanceID id, bool reSeek = false, bool promoteCached = true );
+
+        LazyInstanceBatch loadBatch( instanceID root );
+        LazyInstanceBatch loadBatch( const std::vector<instanceID> & roots );

        //list all instances that one instance depends on (recursive)
        instanceSet * instanceDependencies( instanceID id );
@@ -183,11 +288,8 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
                    std::cerr << "Error at " << __FILE__ << ":" << __LINE__ << " - multiple instances (" << cv->size() << ") with one instanceID (" << id << ") not supported yet." << std::endl;
                    return 0;
                }
-                positionAndSection ps = cv->at( 0 );
-                //extract p, s, call
-                long int off = ps & 0xFFFFFFFFFFFFULL;
-                sectionID sid = ps >> 48;
-                return _dataSections[sid]->getType( off );
+                instancePosition pos = cv->at( 0 );
+                return _dataSections[pos.section]->getType( pos.begin );
            }
            std::cerr << "Error at " << __FILE__ << ":" << __LINE__ << " - instanceID " << id << " not found." << std::endl;
            return 0;
@@ -218,4 +320,3 @@ class SC_LAZYFILE_EXPORT lazyInstMgr {
 };

 #endif //LAZYINSTMGR_H
-
@@ -7,12 +7,13 @@

 class SC_LAZYFILE_EXPORT lazyP21DataSectionReader: public lazyDataSectionReader {
    protected:
+        /** Index the instances in an Edition 1 SCOPE and leave the stream at
+         * the owning entity's record. */
+        bool indexScope();
    public:
        lazyP21DataSectionReader( lazyFileReader * parent, std::ifstream & file, std::streampos start, sectionID sid );

-        void findSectionStart() {
-            _sectionStart = findNormalString( "DATA", true );
-        }
+        void findSectionStart();
        /** gets information (start, end, name, etc) about the next
         * instance in the file and returns it in a namedLazyInstance
         * \sa p21HeaderSectionReader::nextInstance()
@@ -22,4 +23,3 @@ class SC_LAZYFILE_EXPORT lazyP21DataSectionReader: public lazyDataSectionReader
 };

 #endif //LAZYP21DATASECTIONREADER_H
-
@@ -0,0 +1,131 @@
+#ifndef LAZYSUPPORT_H
+#define LAZYSUPPORT_H
+
+#include <cstddef>
+#include <functional>
+#include <iosfwd>
+#include <string>
+#include <vector>
+
+#include "cllazyfile/lazyTypes.h"
+#include "sc_export.h"
+
+class lazyInstMgr;
+class SDAI_Application_instance;
+
+enum LazyDiagnosticSeverity {
+    LAZY_DIAGNOSTIC_INFO,
+    LAZY_DIAGNOSTIC_WARNING,
+    LAZY_DIAGNOSTIC_ERROR,
+    LAZY_DIAGNOSTIC_FATAL
+};
+
+struct SC_LAZYFILE_EXPORT LazyDiagnostic {
+    LazyDiagnosticSeverity severity;
+    instanceID entity;
+    std::string type;
+    lazyFileOffset offset;
+    uint64_t line;
+    std::string attribute;
+    std::string message;
+    uint64_t occurrences;
+
+    LazyDiagnostic(): severity( LAZY_DIAGNOSTIC_INFO ), entity( 0 ), offset( 0 ),
+        line( 0 ), occurrences( 1 ) {}
+};
+
+struct SC_LAZYFILE_EXPORT LazyScanProgress {
+    fileID file;
+    lazyFileOffset offset;
+    lazyFileOffset fileSize;
+    uint64_t instancesScanned;
+
+    LazyScanProgress(): file( 0 ), offset( 0 ), fileSize( 0 ), instancesScanned( 0 ) {}
+};
+
+struct SC_LAZYFILE_EXPORT LazyCacheStatistics {
+    uint64_t instancesScanned;
+    uint64_t instancesLoaded;
+    uint64_t instancesPinned;
+    uint64_t cacheHighWater;
+    uint64_t cacheHits;
+    uint64_t cacheMisses;
+    uint64_t materializations;
+    uint64_t evictions;
+    uint64_t activeBatches;
+    uint64_t dataSections;
+    uint64_t residentSourceBytes;
+    uint64_t sourceBytesHighWater;
+    bool cancelled;
+
+    LazyCacheStatistics(): instancesScanned( 0 ), instancesLoaded( 0 ), instancesPinned( 0 ),
+        cacheHighWater( 0 ), cacheHits( 0 ), cacheMisses( 0 ), materializations( 0 ),
+        evictions( 0 ), activeBatches( 0 ), dataSections( 0 ), residentSourceBytes( 0 ),
+        sourceBytesHighWater( 0 ), cancelled( false ) {}
+};
+
+typedef std::function<void ( const LazyScanProgress & )> LazyProgressCallback;
+typedef std::function<bool ()> LazyCancellationCallback;
+typedef std::function<void ( const LazyDiagnostic & )> LazyDiagnosticCallback;
+
+/** A non-owning, zero-copy view of an indexed instance-ID vector.
+ * The view remains valid until another file is scanned by the manager.
+ */
+class SC_LAZYFILE_EXPORT LazyInstanceIdView {
+    public:
+        typedef instanceRefs::const_iterator const_iterator;
+
+        LazyInstanceIdView(): _ids( 0 ) {}
+        explicit LazyInstanceIdView( const instanceRefs * ids ): _ids( ids ) {}
+
+        const_iterator begin() const;
+        const_iterator end() const;
+        size_t size() const;
+        bool empty() const;
+        instanceID operator[]( size_t index ) const;
+
+    private:
+        const instanceRefs * _ids;
+};
+
+/** A dependency closure materialized and pinned for a bounded operation.
+ * STEPcode parsing remains single-threaded.  Detach immutable conversion data
+ * before releasing the batch or passing work to another thread.
+ */
+class SC_LAZYFILE_EXPORT LazyInstanceBatch {
+    public:
+        LazyInstanceBatch();
+        ~LazyInstanceBatch();
+        LazyInstanceBatch( LazyInstanceBatch && other );
+        LazyInstanceBatch & operator=( LazyInstanceBatch && other );
+
+        LazyInstanceBatch( const LazyInstanceBatch & ) = delete;
+        LazyInstanceBatch & operator=( const LazyInstanceBatch & ) = delete;
+
+        bool valid() const;
+        void release();
+        const std::vector<instanceID> & roots() const;
+        const std::vector<instanceID> & instances() const;
+        SDAI_Application_instance * get( instanceID id ) const;
+
+    private:
+        friend class lazyInstMgr;
+        LazyInstanceBatch( lazyInstMgr * manager, const std::vector<instanceID> & roots,
+            const std::vector<instanceID> & instances );
+
+        lazyInstMgr * _manager;
+        std::vector<instanceID> _roots;
+        std::vector<instanceID> _instances;
+};
+
+/** Adapter preserving a stream-oriented diagnostic presentation. */
+class SC_LAZYFILE_EXPORT LazyTextDiagnosticAdapter {
+    public:
+        explicit LazyTextDiagnosticAdapter( std::ostream & stream );
+        void operator()( const LazyDiagnostic & diagnostic ) const;
+
+    private:
+        std::ostream * _stream;
+};
+
+#endif // LAZYSUPPORT_H
@@ -6,6 +6,7 @@
 #include <iostream>
 #include <vector>
 #include <set>
+#include <string>

 #ifdef HAVE_STDINT_H
 #include <stdint.h>
@@ -29,6 +30,7 @@ enum fileTypeEnum { Part21, Part28 };
 // enum loadingEnum { immediate, lazy };

 typedef uint64_t instanceID;  ///< the number assigned to an instance in the file
+typedef uint64_t lazyFileOffset; ///< byte offset in an exchange file
 typedef uint16_t sectionID;   ///< globally unique index of a sectionReader in a sectionReaderVec_t
 typedef uint16_t fileID;      ///< the index of a lazyFileReader in a lazyFileReaderVec_t. Can be inferred from a sectionID

@@ -42,7 +44,10 @@ typedef uint16_t fileID;      ///< the index of a lazyFileReader in a lazyFileRe
 * section = ( ps >> 48 );
 * TODO: Also 8 bits of flags? Would allow files of 2^40 bytes, or ~1TB.
 */
-typedef uint64_t positionAndSection;
+typedef struct {
+    lazyFileOffset begin;
+    sectionID section;
+} instancePosition;

 typedef std::vector< instanceID > instanceRefs;

@@ -55,7 +60,8 @@ typedef std::set< instanceID > instanceSet;
 * situations, so the information should be kept up-to-date.
 */
 typedef struct {
-    long begin; ///< this is the result of tellg() before reading the instanceID; there may be whitespace or comments, but nothing else.
+    lazyFileOffset begin; ///< byte offset before the instance ID; whitespace or comments may precede it.
+    lazyFileOffset end; ///< byte offset immediately after the terminating semicolon.
    instanceID instance;
    sectionID section;
    /* bool modified; */ /* this will be useful when writing instances - if an instance is
@@ -67,6 +73,7 @@ typedef struct {
    lazyInstanceLoc loc;
    const char * name;
    instanceRefs * refs;
+    std::vector<std::string> * componentTypes; ///< compositional types for a complex instance
 } namedLazyInstance;

 // instanceRefs - map between an instanceID and instances that refer to it
@@ -80,7 +87,7 @@ typedef judyLArray< instanceID, SDAI_Application_instance * > instancesLoaded_t;

 // instanceStreamPos - map instance id to a streampos and data section
 // there could be multiple instances with the same ID, but in different files (or different sections of the same file?)
-typedef judyL2Array< instanceID, positionAndSection > instanceStreamPos_t;
+typedef judyL2Array< instanceID, instancePosition > instanceStreamPos_t;


 // data sections
@@ -93,4 +100,3 @@ typedef std::vector< lazyFileReader * > lazyFileReaderVec_t;
 // NOTE not useful? typedef std::vector< lazyInstance > lazyInstanceVec_t;

 #endif //LAZYTYPES_H
-
@@ -46,12 +46,31 @@ class SC_LAZYFILE_EXPORT sectionReader {
         */
        std::streampos findNormalString( const std::string & str, bool semicolon = false );

+        /** Skip from immediately after a comment's opening slash and star
+         * through its closing star and slash.  Part 21 comments are opaque:
+         * apostrophes and string-control text inside them have no syntax.
+         */
+        bool skipComment();
+
+        /** Skip whitespace and Part 21 comments, leaving the next syntactic
+         * token unread. */
+        bool skipTokenSeparators();
+
+        /** Skip an Edition 1 SCOPE construct, including nested scopes and its
+         * optional export list.  The stream must initially point at '&' and
+         * is left at the owning entity's record. */
+        bool skipScope();
+
+        /** Skip an optional scope export list at the current stream
+         * position. */
+        bool skipScopeExportList();
+
        /** Get a keyword ending with one of delimiters.
         */
        const char * getDelimitedKeyword( const char * delimiters );

        /** Seek to the end of the current instance */
-        std::streampos seekInstanceEnd( instanceRefs ** refs );
+        std::streampos seekInstanceEnd( instanceRefs ** refs, std::vector<std::string> * componentTypes = 0 );

        /// operator>> is very slow?!
        inline void skipWS() {
@@ -63,9 +82,15 @@ class SC_LAZYFILE_EXPORT sectionReader {
        STEPcomplex * CreateSubSuperInstance( const Registry * reg, instanceID fileid, Severity & sev );

    public:
-        SDAI_Application_instance * getRealInstance( const Registry * reg, long int begin, instanceID instance,
+        SDAI_Application_instance * getRealInstance( const Registry * reg, lazyFileOffset begin, instanceID instance,
                const std::string & typeName = "", const std::string & schName = "", bool header = false );

+        /** Return one indexed source record without materializing it.  The
+         * stream position is restored before returning.  This is intended
+         * for lightweight adapters which can detach scalar/reference data
+         * directly from Part 21 source. */
+        std::string sourceRecord( lazyFileOffset begin, uint64_t length );
+
        sectionID ID() const {
            return _sectionID;
        }
@@ -91,13 +116,15 @@ class SC_LAZYFILE_EXPORT sectionReader {
        /** returns the type string for an instance, read straight from the file
         * if this function changes, probably need to change nextInstance() as well
         * don't check errors - they would have been encountered during the initial file scan, and the file is still open so it can't have been modified */
-        const char * getType( long int offset ) {
+        const char * getType( lazyFileOffset offset ) {
            if( offset <= 0 ) {
                return 0;
            }
-            _file.seekg( offset );
+            _file.seekg( static_cast<std::streamoff>( offset ) );
            readInstanceNumber();
-            skipWS();
+            if( !skipTokenSeparators() ) return 0;
+            if( _file.peek() == '&' && !skipScope() ) return 0;
+            if( !skipTokenSeparators() ) return 0;
            return getDelimitedKeyword( ";( /\\" );
        }

@@ -112,4 +139,3 @@ class SC_LAZYFILE_EXPORT sectionReader {
 };

 #endif //SECTIONREADER_H
-
@@ -31,6 +31,8 @@ set(CORE_HDRS
  realTypeDescriptor.h
  Registry.h
  schRename.h
+  schemaInit.h
+  schemaModule.h
  sdai.h
  sdaiApplication_instance.h
  sdaiSelect.h
@@ -68,4 +70,3 @@ install(FILES ${CORE_HDRS}
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -4,6 +4,8 @@
 #include "clstepcore/STEPaggregate.h"
 #include <sc_export.h>

+class SelectTypeDescriptor;
+
 /** \file STEPaggrSelect.h
 * classes SelectAggregate, SelectNode
 */
@@ -14,6 +16,9 @@
 ** This is a minimal representation for a collection of SDAI_Select
 */
 class SC_CORE_EXPORT SelectAggregate  :  public STEPaggregate {
+protected:
+    const SelectTypeDescriptor * _select_type;
+
 public:
    virtual Severity ReadValue( istream & in, ErrorDescriptor * err,
                                const TypeDescriptor * elem_type,
@@ -24,7 +29,7 @@ public:
    virtual SingleLinkNode * NewNode();
    virtual STEPaggregate & ShallowCopy( const STEPaggregate & );

-    SelectAggregate();
+    explicit SelectAggregate( const SelectTypeDescriptor * select_type = 0 );
    virtual ~SelectAggregate();
 };
 typedef        SelectAggregate  *   SelectAggregateH;
@@ -112,6 +112,7 @@ class SC_CORE_EXPORT STEPattribute {
        char SkipBadAttr( istream & in, char * StopChars );
        void AddErrorInfo();
        void STEPwriteError( ostream& out, unsigned int line, const char* desc );
+        void DeleteOwnedPtr();

    public:
        void incrRefCount() {
@@ -232,6 +233,14 @@ class SC_CORE_EXPORT STEPattribute {
            memset( & ptr, 0, sizeof( ptr ) );
        }
        ~STEPattribute();
+        /** Construct storage owned by this attribute from its descriptor.
+         *
+         * Generated early-bound classes normally pass a pointer to one of
+         * their data members to the typed constructors below.  Late-bound
+         * instances have no generated data members, so this constructor
+         * allocates the corresponding value object instead.
+         */
+        explicit STEPattribute( const class AttrDescriptor & d );
        //  INTEGER
        STEPattribute( const class AttrDescriptor & d, SDAI_Integer * p );
        //  BINARY
@@ -48,7 +48,7 @@ public:

    void AssignAggrCreator( AggregateCreator f = 0 );

-    STEPaggregate * CreateAggregate();
+    STEPaggregate * CreateAggregate() const;

    AggrTypeDescriptor( );
    AggrTypeDescriptor( SDAI_Integer b1, SDAI_Integer b2,
@@ -24,6 +24,9 @@ class Registry;
 */
 class SC_CORE_EXPORT EntityDescriptor  :    public TypeDescriptor  {

+    private:
+        void InvalidateLateBoundLayout() const;
+
    protected:

        SDAI_LOGICAL _abstractEntity;
@@ -57,6 +60,22 @@ class SC_CORE_EXPORT EntityDescriptor  :    public TypeDescriptor  {

        virtual ~EntityDescriptor();

+        /** Create an instance of this entity.
+         *
+         * Uses the generated early-bound creator when one is installed and
+         * otherwise constructs a descriptor-backed late-bound instance.
+         */
+        SDAI_Application_instance * CreateEntity() const;
+
+        /** Resolve the inherited attribute layout used by late-bound
+         * instances.
+         *
+         * SchemaModule calls this once after descriptor initialization.
+         * CreateEntity also calls it as a fallback for independently built
+         * descriptor graphs.
+         */
+        void PrepareLateBoundLayout() const;
+
        void InitIAttrs( Registry & reg, const char * schNm );

        const char * GenerateExpress( std::string & buf ) const;
@@ -134,10 +153,12 @@ class SC_CORE_EXPORT EntityDescriptor  :    public TypeDescriptor  {
        }

        void AddSupertype( EntityDescriptor * ed ) {
+            InvalidateLateBoundLayout();
            _supertypes.AddNode( ed );
        }

        void AddExplicitAttr( AttrDescriptor * ad ) {
+            InvalidateLateBoundLayout();
            _explicitAttr.AddNode( ad );
        }

@@ -1,6 +1,8 @@
 #ifndef ENUMTYPEDESCRIPTOR_H
 #define ENUMTYPEDESCRIPTOR_H

+#include <stddef.h>
+
 #include "typeDescriptor.h"

 typedef SDAI_Enum * ( * EnumCreator )();
@@ -15,16 +17,20 @@ class SC_CORE_EXPORT EnumTypeDescriptor  :    public TypeDescriptor  {
            CreateNewEnum = f;
        }

-        SDAI_Enum * CreateEnum();
+        SDAI_Enum * CreateEnum() const;

        EnumTypeDescriptor( ) { }
        EnumTypeDescriptor( const char * nm, PrimitiveType ft,
                            Schema * origSchema, const char * d,
                            EnumCreator f = 0 );

-        virtual ~EnumTypeDescriptor() { }
+        virtual ~EnumTypeDescriptor();
 };

+SC_CORE_EXPORT void RegisterEnumDescriptorElements(
+    const EnumTypeDescriptor & descriptor,
+    const char * const * elements, size_t count );
+
 /** \class EnumerationTypeDescriptor
 * FIXME not implemented
 *
@@ -21,7 +21,14 @@ public:
    Entity__set_var _entities; // not implemented
    Where_rule__list_var _where_rules;
    Schema_ptr _parent_schema;
+#ifdef _MSC_VER
+#pragma warning( push )
+#pragma warning( disable: 4251 )
+#endif
    std::string _rule_text; // non-SDAI
+#ifdef _MSC_VER
+#pragma warning( pop )
+#endif

    Global_rule();
    Global_rule( const char * n, Schema_ptr parent_sch, const std::string & rt );
@@ -0,0 +1,362 @@
+#ifndef SCHEMAINIT_H
+#define SCHEMAINIT_H
+
+#include <stddef.h>
+
+#include "sc_export.h"
+#include "clstepcore/attrDescriptor.h"
+#include "clstepcore/aggrTypeDescriptor.h"
+#include "clstepcore/dictSchema.h"
+#include "clstepcore/entityDescriptor.h"
+#include "clstepcore/enumTypeDescriptor.h"
+#include "clstepcore/selectTypeDescriptor.h"
+#include "clstepcore/schemaModule.h"
+
+class Derived_attribute;
+class Inverse_attribute;
+class ComplexCollect;
+class Registry;
+
+/** Compact records used by API v2 generated schema initialization. */
+struct SC_CORE_EXPORT SchemaInitRecord {
+    Schema ** slot;
+    const char * name;
+    ModelContentsCreator modelContentsCreator;
+};
+
+struct SC_CORE_EXPORT EntityDescriptorInitRecord {
+    EntityDescriptor ** slot;
+    const char * name;
+    Schema ** schemaSlot;
+    Logical abstractEntity;
+    Logical externalMapping;
+    Creator creator;
+};
+
+struct SC_CORE_EXPORT EntitySupertypeInitRecord {
+    EntityDescriptor * supertype;
+};
+
+enum TypeDescriptorInitKind {
+    TypeDescriptorInit_Base,
+    TypeDescriptorInit_Enum,
+    TypeDescriptorInit_Select,
+    TypeDescriptorInit_Aggregate,
+    TypeDescriptorInit_Array,
+    TypeDescriptorInit_List,
+    TypeDescriptorInit_Set,
+    TypeDescriptorInit_Bag
+};
+
+struct SC_CORE_EXPORT TypeDescriptorInitRecord {
+    void * slot;
+    TypeDescriptorInitKind kind;
+    const char * name;
+    PrimitiveType fundamentalType;
+    Schema ** schemaSlot;
+    const char * description;
+    int uniqueElements;
+    SelectCreator selectCreator;
+    EnumCreator enumCreator;
+    AggregateCreator aggregateCreator;
+
+    TypeDescriptorInitRecord( TypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription );
+    TypeDescriptorInitRecord( EnumTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              EnumCreator creator );
+    TypeDescriptorInitRecord( SelectTypeDescriptor ** descriptorSlot,
+                              int unique, const char * typeName,
+                              PrimitiveType type, Schema ** schema,
+                              const char * typeDescription,
+                              SelectCreator creator );
+    TypeDescriptorInitRecord( AggrTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              AggregateCreator creator );
+    TypeDescriptorInitRecord( ArrayTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              AggregateCreator creator );
+    TypeDescriptorInitRecord( ListTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              AggregateCreator creator );
+    TypeDescriptorInitRecord( SetTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              AggregateCreator creator );
+    TypeDescriptorInitRecord( BagTypeDescriptor ** descriptorSlot,
+                              const char * typeName, PrimitiveType type,
+                              Schema ** schema, const char * typeDescription,
+                              AggregateCreator creator );
+};
+
+/**
+ * Attribute descriptor record.  The overloaded constructors preserve the
+ * concrete type of generated descriptor slots without templates or casts in
+ * generated translation units.
+ */
+struct SC_CORE_EXPORT AttributeInitRecord {
+    AttrDescriptor ** attributeSlot;
+    Derived_attribute ** derivedSlot;
+    Inverse_attribute ** inverseSlot;
+    const char * name;
+    const TypeDescriptor * domain;
+    Logical optional;
+    Logical unique;
+    AttrType_Enum attrType;
+    const char * initializer;
+    const char * invertedAttribute;
+    const char * invertedEntity;
+
+    AttributeInitRecord( AttrDescriptor ** slot, const char * attrName,
+                         const TypeDescriptor * domainType, Logical isOptional,
+                         Logical isUnique, AttrType_Enum type,
+                         const char * init = 0 );
+    AttributeInitRecord( Derived_attribute ** slot, const char * attrName,
+                         const TypeDescriptor * domainType, Logical isOptional,
+                         Logical isUnique, AttrType_Enum type,
+                         const char * init = 0 );
+    AttributeInitRecord( Inverse_attribute ** slot, const char * attrName,
+                         const TypeDescriptor * domainType, Logical isOptional,
+                         Logical isUnique, const char * invertedAttr,
+                         const char * invertedEnt );
+};
+
+enum ComplexNodeInitKind {
+    ComplexNodeInit_Simple,
+    ComplexNodeInit_And,
+    ComplexNodeInit_Or,
+    ComplexNodeInit_AndOr
+};
+
+struct SC_CORE_EXPORT ComplexNodeInitRecord {
+    ComplexNodeInitKind kind;
+    const char * name;
+    size_t firstChild;
+    size_t nextSibling;
+};
+
+struct SC_CORE_EXPORT ComplexListInitRecord {
+    size_t rootNode;
+};
+
+struct SC_CORE_EXPORT GlobalRuleInitRecord {
+    const char * name;
+    const char * text;
+};
+
+enum SchemaImageDescriptorRefKind {
+    SchemaImageRef_None,
+    SchemaImageRef_Entity,
+    SchemaImageRef_Type,
+    SchemaImageRef_Builtin,
+    SchemaImageRef_Aggregate
+};
+
+struct SC_CORE_EXPORT SchemaImageDescriptorRef {
+    uint32_t kind;
+    uint32_t schema;
+    uint32_t index;
+};
+
+struct SC_CORE_EXPORT SchemaImageSchemaRecord {
+    uint32_t name;
+    uint32_t firstEntity;
+    uint32_t entityCount;
+    uint32_t firstType;
+    uint32_t typeCount;
+};
+
+struct SC_CORE_EXPORT SchemaImageEntityRecord {
+    uint32_t schema;
+    uint32_t name;
+    uint32_t flags;
+    uint32_t supertypeStatement;
+    uint32_t firstSupertype;
+    uint32_t supertypeCount;
+    uint32_t firstAttribute;
+    uint32_t attributeCount;
+    uint32_t firstWhereRule;
+    uint32_t whereRuleCount;
+    uint32_t firstUniqueRule;
+    uint32_t uniqueRuleCount;
+};
+
+enum SchemaImageEntityFlags {
+    SchemaImageEntity_Abstract = 1u << 0,
+    SchemaImageEntity_ExternalMapping = 1u << 1
+};
+
+struct SC_CORE_EXPORT SchemaImageTypeRecord {
+    uint32_t schema;
+    uint32_t name;
+    uint32_t description;
+    uint32_t fundamentalType;
+    uint32_t descriptorKind;
+    int32_t uniqueElements;
+    SchemaImageDescriptorRef referent;
+    uint32_t aggregate;
+    uint32_t firstSelectElement;
+    uint32_t selectElementCount;
+    uint32_t firstWhereRule;
+    uint32_t whereRuleCount;
+    uint32_t firstEnumElement;
+    uint32_t enumElementCount;
+};
+
+struct SC_CORE_EXPORT SchemaImageAttributeRecord {
+    uint32_t name;
+    SchemaImageDescriptorRef domain;
+    uint32_t optional;
+    uint32_t unique;
+    uint32_t attrType;
+    uint32_t initializer;
+    uint32_t invertedAttribute;
+    uint32_t invertedEntity;
+};
+
+struct SC_CORE_EXPORT SchemaImageAggregateRecord {
+    uint32_t schema;
+    uint32_t description;
+    uint32_t fundamentalType;
+    SchemaImageDescriptorRef referent;
+    uint32_t bound1Type;
+    int32_t bound1;
+    uint32_t bound1Text;
+    uint32_t bound2Type;
+    int32_t bound2;
+    uint32_t bound2Text;
+    uint32_t optionalElements;
+    uint32_t uniqueElements;
+};
+
+struct SC_CORE_EXPORT SchemaImageRuleRecord {
+    uint32_t text;
+};
+
+enum SchemaImageSchemaTextKind {
+    SchemaImageText_GlobalRule,
+    SchemaImageText_Function,
+    SchemaImageText_Procedure
+};
+
+struct SC_CORE_EXPORT SchemaImageSchemaTextRecord {
+    uint32_t schema;
+    uint32_t kind;
+    uint32_t name;
+    uint32_t text;
+};
+
+struct SC_CORE_EXPORT SchemaImageRenameRecord {
+    SchemaImageDescriptorRef descriptor;
+    uint32_t schema;
+    uint32_t name;
+};
+
+struct SC_CORE_EXPORT SchemaImageSchemaBinding {
+    Schema ** schemaSlot;
+    ModelContentsCreator modelContentsCreator;
+    SchemaModule * module;
+};
+
+struct SC_CORE_EXPORT SchemaImageTypeBinding {
+    void * slot;
+    SelectCreator selectCreator;
+    EnumCreator enumCreator;
+    AggregateCreator aggregateCreator;
+};
+
+enum SchemaLoadError {
+    SchemaLoad_Ok,
+    SchemaLoad_UnsupportedVersion,
+    SchemaLoad_TruncatedImage,
+    SchemaLoad_InvalidOffset,
+    SchemaLoad_InvalidString,
+    SchemaLoad_InvalidReference,
+    SchemaLoad_CountMismatch,
+    SchemaLoad_MissingBinding,
+    SchemaLoad_ModuleFailure
+};
+
+struct SC_CORE_EXPORT SchemaLoadResult {
+    SchemaLoadError error;
+    uint32_t record;
+
+    bool Succeeded() const {
+        return error == SchemaLoad_Ok;
+    }
+    const char * Message() const;
+};
+
+SC_CORE_EXPORT SchemaLoadResult InitializeSchemaFromImage(
+    Registry & registry, const SchemaModuleImage & image,
+    const SchemaImageSchemaBinding * schemaBindings,
+    size_t schemaBindingCount,
+    const SchemaImageTypeBinding * typeBindings,
+    size_t typeBindingCount, SchemaLoadContext & context );
+
+enum PackedComplexImageVersion {
+    PackedComplexImageVersion_1 = 1
+};
+
+struct SC_CORE_EXPORT PackedComplexImage {
+    uint32_t version;
+    uint32_t byteSize;
+    uint32_t stringOffset;
+    uint32_t stringBytes;
+    uint32_t nodeOffset;
+    uint32_t nodeCount;
+    uint32_t listOffset;
+    uint32_t listCount;
+};
+
+struct SC_CORE_EXPORT PackedComplexNode {
+    uint32_t kind;
+    uint32_t name;
+    uint32_t firstChild;
+    uint32_t nextSibling;
+};
+
+struct SC_CORE_EXPORT PackedComplexList {
+    uint32_t rootNode;
+};
+
+SC_CORE_EXPORT ComplexCollect * InitializePackedComplexSupport(
+    const PackedComplexImage & image, SchemaLoadResult * result = 0 );
+
+SC_CORE_EXPORT void InitializeSchemas( Registry & reg,
+                                       const SchemaInitRecord * records,
+                                       size_t count );
+SC_CORE_EXPORT void InitializeSchemaModuleImages(
+    const SchemaInitRecord * records, size_t count );
+SC_CORE_EXPORT void InitializeEntityDescriptors(
+    const EntityDescriptorInitRecord * records, size_t count );
+SC_CORE_EXPORT void InitializeTypeDescriptors(
+    const TypeDescriptorInitRecord * records, size_t count );
+SC_CORE_EXPORT void InitializeTypeMetadata(
+    Registry & reg, Schema & schema, TypeDescriptor & type,
+    const TypeDescriptor * referent,
+    const TypeDescriptor * const * selectElements, size_t selectElementCount );
+SC_CORE_EXPORT void InitializeEntityMetadata(
+    Registry & reg, EntityDescriptor & entity, Schema & schema,
+    const EntitySupertypeInitRecord * supertypes, size_t supertypeCount,
+    const AttributeInitRecord * attributes, size_t attributeCount );
+SC_CORE_EXPORT void InitializeWhereRules(
+    TypeDescriptor & owner, const char * const * rules, size_t count );
+SC_CORE_EXPORT void InitializeUniquenessRules(
+    EntityDescriptor & owner, const char * const * rules, size_t count );
+SC_CORE_EXPORT void InitializeGlobalRules(
+    Schema & schema, const GlobalRuleInitRecord * rules, size_t count );
+SC_CORE_EXPORT void InitializeFunctions(
+    Schema & schema, const char * const * functions, size_t count );
+SC_CORE_EXPORT void InitializeProcedures(
+    Schema & schema, const char * const * procedures, size_t count );
+SC_CORE_EXPORT ComplexCollect * InitializeComplexSupport(
+    const ComplexNodeInitRecord * nodes, size_t nodeCount,
+    const ComplexListInitRecord * lists, size_t listCount );
+
+#endif
@@ -0,0 +1,171 @@
+#ifndef SCHEMAMODULE_H
+#define SCHEMAMODULE_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <vector>
+
+#include "sc_export.h"
+
+class AttrDescriptor;
+class EntityDescriptor;
+class Schema;
+class TypeDescriptor;
+
+enum SchemaModuleSlotKind {
+    SchemaModuleSlot_Entity,
+    SchemaModuleSlot_Type,
+    SchemaModuleSlot_EnumType,
+    SchemaModuleSlot_SelectType,
+    SchemaModuleSlot_AggregateType,
+    SchemaModuleSlot_ArrayType,
+    SchemaModuleSlot_ListType,
+    SchemaModuleSlot_SetType,
+    SchemaModuleSlot_BagType,
+    SchemaModuleSlot_Attribute,
+    SchemaModuleSlot_DerivedAttribute,
+    SchemaModuleSlot_InverseAttribute
+};
+
+struct SC_CORE_EXPORT SchemaModuleSlot {
+    const void * slot;
+    SchemaModuleSlotKind kind;
+};
+
+enum SchemaModuleImageVersion {
+    SchemaModuleImageVersion_1 = 1,
+    SchemaModuleImageVersion_2 = 2
+};
+
+enum SchemaModuleImageFlags {
+    SchemaModuleImage_FullMetadata = 0,
+    SchemaModuleImage_StructuralMetadata = 1u << 0
+};
+
+/**
+ * Relocation-free generated header for a schema module image.
+ *
+ * Version 1 records only stable generated-ID counts.  Version 2 describes
+ * one bounded block of offset-based schemas, descriptors, metadata, and
+ * strings.  Runtime loading validates the complete block before constructing
+ * descriptors or changing a Registry.
+ */
+struct SC_CORE_EXPORT SchemaModuleImage {
+    uint32_t version;
+    uint32_t entityCount;
+    uint32_t typeCount;
+    uint32_t attributeCount;
+
+    /* Version 2 fields.  Version 1 initializers leave these zero. */
+    uint32_t byteSize;
+    uint32_t flags;
+    uint32_t schemaCount;
+    uint32_t stringBytes;
+    uint32_t schemaOffset;
+    uint32_t entityOffset;
+    uint32_t typeOffset;
+    uint32_t attributeOffset;
+    uint32_t aggregateCount;
+    uint32_t aggregateOffset;
+    uint32_t referenceCount;
+    uint32_t referenceOffset;
+    uint32_t ruleCount;
+    uint32_t ruleOffset;
+    uint32_t schemaTextCount;
+    uint32_t schemaTextOffset;
+    uint32_t enumElementCount;
+    uint32_t enumElementOffset;
+    uint32_t stringOffset;
+    uint32_t reserved;
+    uint64_t fingerprint;
+    uint32_t renameCount;
+    uint32_t renameOffset;
+};
+
+class SchemaModule;
+
+/**
+ * Per-load descriptor collection used by packed API v2 schema images.
+ *
+ * Keeping this state explicit makes independent schema loads reentrant and
+ * avoids the process-global capture map retained for version-1 images.
+ */
+class SC_CORE_EXPORT SchemaLoadContext {
+    class Impl;
+    Impl * _impl;
+
+    SchemaLoadContext( const SchemaLoadContext & );
+    SchemaLoadContext & operator=( const SchemaLoadContext & );
+    friend class SchemaModule;
+
+public:
+    SchemaLoadContext();
+    ~SchemaLoadContext();
+
+    void Begin( Schema & schema );
+    void RecordEntity( Schema & schema, const EntityDescriptor * entity );
+    void RecordType( Schema & schema, const TypeDescriptor * type );
+    void RecordAttribute( Schema & schema, const AttrDescriptor * attribute );
+};
+
+SC_CORE_EXPORT void RecordSchemaModuleEntity(
+    Schema & schema, const EntityDescriptor * entity );
+SC_CORE_EXPORT void RecordSchemaModuleType(
+    Schema & schema, const TypeDescriptor * type );
+SC_CORE_EXPORT void RecordSchemaModuleAttribute(
+    Schema & schema, const AttrDescriptor * attribute );
+SC_CORE_EXPORT void BeginSchemaModuleImage( Schema & schema );
+
+/**
+ * Stable API v2 view of a generated schema.
+ *
+ * Generated EntityId, TypeId, and AttributeId enumerations are converted to
+ * indexes before calling this class.  Keeping the public lookup API separate
+ * from generated descriptor globals allows the underlying representation to
+ * move from C++ objects to packed schema data without another API break.
+ */
+class SC_CORE_EXPORT SchemaModule {
+    Schema * _schema;
+#ifdef _MSC_VER
+#pragma warning( push )
+#pragma warning( disable: 4251 )
+#endif
+    std::vector<const EntityDescriptor *> _entities;
+    std::vector<const TypeDescriptor *> _types;
+    std::vector<const AttrDescriptor *> _attributes;
+    uint64_t _fingerprint;
+#ifdef _MSC_VER
+#pragma warning( pop )
+#endif
+
+public:
+    SchemaModule();
+    ~SchemaModule();
+
+    void Initialize(
+        Schema & schema,
+        const EntityDescriptor * const * entities, size_t entityCount,
+        const TypeDescriptor * const * types, size_t typeCount,
+        const AttrDescriptor * const * attributes, size_t attributeCount );
+    void InitializeFromSlots(
+        Schema & schema,
+        const SchemaModuleSlot * entities, size_t entityCount,
+        const SchemaModuleSlot * types, size_t typeCount,
+        const SchemaModuleSlot * attributes, size_t attributeCount );
+    void InitializeFromImage( Schema & schema,
+                              const SchemaModuleImage & image );
+    bool InitializeFromContext( Schema & schema, SchemaLoadContext & context,
+                                uint64_t fingerprint );
+
+    bool IsInitialized() const;
+    const Schema & GetSchema() const;
+    const EntityDescriptor * Entity( size_t id ) const;
+    const TypeDescriptor * Type( size_t id ) const;
+    const AttrDescriptor * Attribute( size_t id ) const;
+    size_t EntityCount() const;
+    size_t TypeCount() const;
+    size_t AttributeCount() const;
+    uint64_t Fingerprint() const;
+};
+
+#endif
@@ -17,7 +17,13 @@
 /**
 ** \file sdaiSelect.h class definition for the select superclass SDAI_Select.
 **/
+class STEPaggregate;
+
 class SC_CORE_EXPORT SDAI_Select {
+    private:
+        class Storage;
+        Storage * _storage;
+
    protected:
        const SelectTypeDescriptor * _type;
        const TypeDescriptor    *   underlying_type;
@@ -36,8 +42,11 @@ class SC_CORE_EXPORT SDAI_Select {

        int IsUnique( const BASE_TYPE bt ) const;

-        virtual const TypeDescriptor * AssignEntity( SDAI_Application_instance * se ) = 0;
-        virtual SDAI_Select * NewSelect() = 0;
+        virtual const TypeDescriptor * AssignEntity( SDAI_Application_instance * se );
+        virtual SDAI_Select * NewSelect();
+
+        void * ValueAddress();
+        const void * ValueAddress() const;
    public:
        Severity severity() const;
        Severity severity( Severity );
@@ -47,7 +56,7 @@ class SC_CORE_EXPORT SDAI_Select {
        void ClearError();
        // clears error

-        virtual BASE_TYPE ValueType() const = 0;
+        virtual BASE_TYPE ValueType() const;

        // constructors
        SDAI_Select( const SelectTypeDescriptor * s = 0,
@@ -72,28 +81,57 @@ class SC_CORE_EXPORT SDAI_Select {
        virtual void STEPwrite_verbose( ostream & out = cout, const char * = 0 )
        const;

-        virtual void STEPwrite_content( ostream & out, const char * = 0 ) const = 0;
+        virtual void STEPwrite_content( ostream & out, const char * = 0 ) const;


        Severity StrToVal( const char * val, const char * selectType,
                           ErrorDescriptor * err, InstMgrBase * instances = 0 );
        virtual Severity StrToVal_content( const char *,
-                                           InstMgrBase * instances = 0 ) = 0;
+                                           InstMgrBase * instances = 0 );

        Severity STEPread( istream & in, ErrorDescriptor * err,
                           InstMgrBase * instances = 0, const char * utype = 0,
                           int addFileId = 0, const char * = NULL );

-        // abstract function
+        // Descriptor-driven default; API v1 SELECTs may override it.
        virtual Severity STEPread_content( istream & in = cin,
                                           InstMgrBase * instances = 0,
                                           const char * utype = 0,
                                           int addFileId = 0,
-                                           const char * currSch = 0 ) = 0;
+                                           const char * currSch = 0 );

        //windows complains if operator= is pure virtual, perhaps because the impl is not in the lib with the definition
        //linux has a regression if the pure virtual operator= is commented out
        virtual SDAI_Select & operator =( const SDAI_Select & other );
+        SDAI_Select & operator =( const SDAI_Select * other );
+        SDAI_Select * Clone() const;
+
+        // Descriptor-driven value API used by generated API v2 classes and
+        // by applications that do not need per-choice early-bound members.
+        bool SetInteger( const TypeDescriptor *, SDAI_Integer );
+        bool SetReal( const TypeDescriptor *, SDAI_Real );
+        bool SetString( const TypeDescriptor *, const SDAI_String & );
+        bool SetBinary( const TypeDescriptor *, const SDAI_Binary & );
+        bool SetEnum( const TypeDescriptor *, const SDAI_Enum & );
+        bool SetSelect( const TypeDescriptor *, const SDAI_Select & );
+        bool SetAggregate( const TypeDescriptor *, const STEPaggregate & );
+        bool SetEntity( SDAI_Application_instance * );
+
+        SDAI_Integer * IntegerValue();
+        const SDAI_Integer * IntegerValue() const;
+        SDAI_Real * RealValue();
+        const SDAI_Real * RealValue() const;
+        SDAI_String * StringValue();
+        const SDAI_String * StringValue() const;
+        SDAI_Binary * BinaryValue();
+        const SDAI_Binary * BinaryValue() const;
+        SDAI_Enum * EnumValue();
+        const SDAI_Enum * EnumValue() const;
+        SDAI_Select * SelectValue();
+        const SDAI_Select * SelectValue() const;
+        STEPaggregate * AggregateValue();
+        const STEPaggregate * AggregateValue() const;
+        SDAI_Application_instance * EntityValue() const;

        //FIXME set_null always returns true. why not void?!
        bool set_null();
@@ -19,7 +19,7 @@ public:
        CreateNewSelect = f;
    }

-    SDAI_Select * CreateSelect();
+    SDAI_Select * CreateSelect() const;

    SelectTypeDescriptor( int b, const char * nm, PrimitiveType ft,
                          Schema * origSchema,
@@ -58,7 +58,7 @@ struct freelist_head {
 #endif
 };

-char * nnew();
+char * nnew(void);

 #include "error.h"

@@ -93,11 +93,10 @@
 /* function pointer types */
 /**************************/

-typedef void ( *voidFuncptr )();
-typedef int ( *intFuncptr )();
+typedef void ( *voidFuncptr )(void);
+typedef int ( *intFuncptr )(void);
+

-/* Option index - can we get rid of this? */
-extern SC_EXPRESS_EXPORT int sc_optind;

 #endif    /* BASIC_H */

@@ -108,6 +108,7 @@ extern SC_EXPRESS_EXPORT char * KW_SUPERTYPE;
 extern SC_EXPRESS_EXPORT char * KW_TAN;
 extern SC_EXPRESS_EXPORT char * KW_THEN;
 extern SC_EXPRESS_EXPORT char * KW_TO;
+extern SC_EXPRESS_EXPORT char * KW_TREAT;
 extern SC_EXPRESS_EXPORT char * KW_TRUE;
 extern SC_EXPRESS_EXPORT char * KW_TYPE;
 extern SC_EXPRESS_EXPORT char * KW_TYPEOF;
@@ -83,7 +83,7 @@ typedef enum {
    OP_MINUS,       OP_MOD,         OP_NEGATE,
    OP_NOT,         OP_NOT_EQUAL,       OP_OR,
    OP_PLUS,        OP_REAL_DIV,        OP_SUBCOMPONENT,
-    OP_TIMES,       OP_XOR,         OP_UNKNOWN,
+    OP_TIMES,       OP_TREAT,       OP_XOR,         OP_UNKNOWN,
    OP_LAST /**< must be last - used only to size tables */
 } Op_Code;

@@ -3,6 +3,6 @@

 #include "sc_export.h"

-SC_EXPRESS_EXPORT void FACTORYinitialize();
+SC_EXPRESS_EXPORT void FACTORYinitialize(void);

 #endif /* __FACTORY_H_ */
@@ -3,6 +3,6 @@

 #include "sc_export.h"

-SC_EXPRESS_EXPORT void MEMORYinitialize();
+SC_EXPRESS_EXPORT void MEMORYinitialize(void);

 #endif // __MEMORY_H
@@ -47,6 +47,25 @@

 extern SC_EXPRESS_EXPORT int print_objects_while_running;

+/*************************/
+/* Refinement structures */
+/*************************/
+
+/* Maximum length for type name lookups */
+#define MAX_TYPE_NAME_LENGTH 512
+
+/** Structure to track type refinements from TYPEOF guards in AND expressions */
+typedef struct Refinement_ {
+    Variable variable;       /**< the variable being refined */
+    Type refined_type;       /**< the narrowed type */
+    struct Refinement_ *next; /**< next refinement in the chain */
+} *Refinement;
+
+/** Context for passing refinements through expression resolution */
+typedef struct RefinementContext_ {
+    Refinement refinements;  /**< linked list of active refinements */
+} *RefinementContext;
+
 /* macros */

 /* cheaper doing the check here, then inside the function call.  Return */
@@ -237,6 +237,9 @@ extern SC_EXPRESS_EXPORT struct freelist_head TYPEBODY_fl;
 #define TYPEis_oneof(t)     ((t)->u.type->body->type == oneof_)
 #define TYPEis_entity(t)    ((t)->u.type->body->type == entity_)
 #define TYPEis_enumeration(t)   ((t)->u.type->body->type == enumeration_)
+/** Shallow aggregate check - returns true if type has a base (characteristic of aggregates).
+ * Does NOT follow type definition chains. For deep unwrapping through typedef chains,
+ * use TYPEget_nonaggregate_base_type() or TYPEget_aggregate_base(). */
 #define TYPEis_aggregate(t) ((t)->u.type->body->base)
 #define TYPEis_aggregate_raw(t) ((t)->u.type->body->type == aggregate_)
 #define TYPEis_array(t)     ((t)->u.type->body->type == array_)
@@ -303,6 +306,7 @@ extern SC_EXPRESS_EXPORT void TYPEcleanup( void );

 extern SC_EXPRESS_EXPORT bool TYPEinherits_from( Type, enum type_enum );
 extern SC_EXPRESS_EXPORT Type TYPEget_nonaggregate_base_type( Type );
+extern SC_EXPRESS_EXPORT Type TYPEget_aggregate_base( Type );

 extern SC_EXPRESS_EXPORT Type TYPEcreate_user_defined_type( Type, Scope, struct Symbol_ * );
 extern SC_EXPRESS_EXPORT Type TYPEcreate_user_defined_tag( Type, Scope, struct Symbol_ * );
@@ -15,7 +15,7 @@ BUILDNAME:STRING=${CTEST_BUILD_NAME}
 SC_ENABLE_TESTING:BOOL=ON
 SC_ENABLE_COVERAGE:BOOL=ON
 SC_BUILD_SCHEMAS:STRING=ALL
-SC_BUILD_TYPE:STRING=Debug
+CMAKE_BUILD_TYPE:STRING=Debug
 ")

 set(LCOV_OUT "${CTEST_BINARY_DIRECTORY}/lcov_html")
@@ -9,7 +9,7 @@ set(CTEST_INITIAL_CACHE "
 SITE:STRING=${CTEST_SITE}
 BUILDNAME:STRING=${CTEST_BUILD_NAME}
 SC_ENABLE_TESTING:BOOL=ON
-SC_BUILD_TYPE:STRING=Debug
+CMAKE_BUILD_TYPE:STRING=Debug
 ")


@@ -121,17 +121,17 @@ Severity SDAI_Binary::ReadBinary( istream & in, ErrorDescriptor * err, int Assig
            if( !validDelimiters ) {
                err->GreaterSeverity( SEVERITY_WARNING );
                if( needDelims )
-                    sprintf( messageBuf,
+                    snprintf( messageBuf, sizeof(messageBuf),
                             "Binary value missing double quote delimiters.\n" );
                else
-                    sprintf( messageBuf,
+                    snprintf( messageBuf, sizeof(messageBuf),
                             "Mismatched double quote delimiters for binary.\n" );
                err->AppendToDetailMsg( messageBuf );
                err->AppendToUserMsg( messageBuf );
            }
        } else {
            err->GreaterSeverity( SEVERITY_WARNING );
-            sprintf( messageBuf, "Invalid binary value.\n" );
+            snprintf( messageBuf, sizeof(messageBuf), "Invalid binary value.\n" );
            err->AppendToDetailMsg( messageBuf );
            err->AppendToUserMsg( messageBuf );
        }
@@ -211,10 +211,10 @@ Severity SDAI_LOGICAL::ReadEnum( istream & in, ErrorDescriptor * err, int Assign
                if( !validDelimiters ) {
                    err->GreaterSeverity( SEVERITY_WARNING );
                    if( needDelims )
-                        sprintf( messageBuf,
+                        snprintf( messageBuf, sizeof(messageBuf),
                                 "Enumerated value has invalid period delimiters.\n" );
                    else
-                        sprintf( messageBuf,
+                        snprintf( messageBuf, sizeof(messageBuf),
                                 "Mismatched period delimiters for enumeration.\n" );
                    err->AppendToDetailMsg( messageBuf );
                    err->AppendToUserMsg( messageBuf );
@@ -241,7 +241,7 @@ Severity SDAI_LOGICAL::ReadEnum( istream & in, ErrorDescriptor * err, int Assign
        } else {
            in.putback( c );
            err->GreaterSeverity( SEVERITY_WARNING );
-            sprintf( messageBuf, "Invalid enumeration value.\n" );
+            snprintf( messageBuf, sizeof(messageBuf), "Invalid enumeration value.\n" );
            err->AppendToDetailMsg( messageBuf );
            err->AppendToUserMsg( messageBuf );
        }
@@ -489,10 +489,10 @@ Severity SDAI_Enum::ReadEnum( istream & in, ErrorDescriptor * err, int AssignVal
                if( !validDelimiters ) {
                    err->GreaterSeverity( SEVERITY_WARNING );
                    if( needDelims )
-                        sprintf( messageBuf,
+                        snprintf( messageBuf, sizeof(messageBuf),
                                 "Enumerated value has invalid period delimiters.\n" );
                    else
-                        sprintf( messageBuf,
+                        snprintf( messageBuf, sizeof(messageBuf),
                                 "Mismatched period delimiters for enumeration.\n" );
                    err->AppendToDetailMsg( messageBuf );
                    err->AppendToUserMsg( messageBuf );
@@ -519,7 +519,7 @@ Severity SDAI_Enum::ReadEnum( istream & in, ErrorDescriptor * err, int AssignVal
        } else {
            in.putback( c );
            err->GreaterSeverity( SEVERITY_WARNING );
-            sprintf( messageBuf, "Invalid enumeration value.\n" );
+            snprintf( messageBuf, sizeof(messageBuf), "Invalid enumeration value.\n" );
            err->AppendToDetailMsg( messageBuf );
            err->AppendToUserMsg( messageBuf );
        }
@@ -21,7 +21,7 @@ if(BUILD_SHARED_LIBS)
 endif()

 if(BUILD_STATIC_LIBS)
-  SC_ADDLIB(stepeditor-static STATIC SOURCES ${EDITOR_SRCS} LINK_LIBRARIES stepcore-static stepdai-static steputils-static)
+  SC_ADDLIB(stepeditor-static STATIC SOURCES ${EDITOR_SRCS} LINK_LIBRARIES steputils-static stepdai-static stepcore-static)
 endif()

 # Local Variables:
@@ -528,7 +528,7 @@ int STEPfile::ReadData1( istream & in ) {
    } // end while loop

    if( _entsNotCreated ) {
-        sprintf( buf,
+        snprintf( buf, sizeof(buf),
                 "STEPfile Reading File: Unable to create %d instances.\n\tIn first pass through DATA section. Check for invalid entity types.\n",
                 _entsNotCreated );
        _error.AppendToUserMsg( buf );
@@ -647,7 +647,7 @@ int STEPfile::ReadData2( istream & in, bool useTechCor ) {
    } // end while loop

    if( _entsInvalid ) {
-        sprintf( buf,
+        snprintf( buf, sizeof(buf),
                 "%s \n\tTotal instances: %d \n\tInvalid instances: %d \n\tIncomplete instances (includes invalid instances): %d \n\t%s: %d.\n",
                 "Second pass complete - instance summary:", total_instances,
                 _entsInvalid, _entsIncomplete, "Warnings",
@@ -1321,7 +1321,7 @@ SDAI_Application_instance * STEPfile::ReadInstance( istream & in, ostream & out,
                }
            } else {
                if( node->CurrState() == completeSE ) {
-                    sprintf( errbuf, "WARNING in WORKING FILE: changing instance #%d state from completeSE to incompleteSE.\n", fileid );
+                    snprintf( errbuf, sizeof(errbuf), "WARNING in WORKING FILE: changing instance #%d state from completeSE to incompleteSE.\n", fileid );
                    _error.AppendToUserMsg( errbuf );
                    if( _fileType != WORKING_SESSION ) {
                        node->ChangeState( incompleteSE );
@@ -1643,7 +1643,7 @@ Severity STEPfile::AppendFile( istream * in, bool useTechCor ) {
        }
        SetFileType( WORKING_SESSION );
    } else {
-        sprintf( errbuf,
+        snprintf( errbuf, sizeof(errbuf),
                 "Faulty input at beginning of file. \"ISO-10303-21;\" or"
                 " \"STEP_WORKING_SESSION;\" expected. File not read: %s\n",
                 ( ( FileName().compare( "-" ) == 0 ) ? "standard input" : FileName().c_str() ) );
@@ -1658,14 +1658,14 @@ Severity STEPfile::AppendFile( istream * in, bool useTechCor ) {
    rval = ReadHeader( *in );
    cout << "\nHEADER read:";
    if( rval < SEVERITY_WARNING ) {
-        sprintf( errbuf,
+        snprintf( errbuf, sizeof(errbuf),
                 "Error: non-recoverable error in reading header section. "
                 "There were %d errors encountered. Rest of file is ignored.\n",
                 _errorCount );
        _error.AppendToUserMsg( errbuf );
        return rval;
    } else if( rval != SEVERITY_NULL ) {
-        sprintf( errbuf, "  %d  ERRORS\t  %d  WARNINGS\n\n",
+        snprintf( errbuf, sizeof(errbuf), "  %d  ERRORS\t  %d  WARNINGS\n\n",
                 _errorCount, _warningCount );
        cout << errbuf;
    } else {
@@ -1683,7 +1683,7 @@ Severity STEPfile::AppendFile( istream * in, bool useTechCor ) {

    cout << "\nFIRST PASS complete:  " << total_insts
         << " instances created.\n";
-    sprintf( errbuf,
+    snprintf( errbuf, sizeof(errbuf),
             "  %d  ERRORS\t  %d  WARNINGS\n\n",
             _errorCount, _warningCount );
    cout << errbuf;
@@ -1727,7 +1727,7 @@ Severity STEPfile::AppendFile( istream * in, bool useTechCor ) {
    //check for "ENDSEC;"
    ReadTokenSeparator( *in2 );
    if( total_insts != valid_insts ) {
-        sprintf( errbuf, "%d invalid instances in file: %s\n",
+        snprintf( errbuf, sizeof(errbuf), "%d invalid instances in file: %s\n",
                 total_insts - valid_insts, ( ( FileName().compare( "-" ) == 0 ) ? "standard input" : FileName().c_str() ) );
        _error.AppendToUserMsg( errbuf );
        CloseInputFile( in2 );
@@ -1736,7 +1736,7 @@ Severity STEPfile::AppendFile( istream * in, bool useTechCor ) {

    cout << "\nSECOND PASS complete:  " << valid_insts
         << " instances valid.\n";
-    sprintf( errbuf,
+    snprintf( errbuf, sizeof(errbuf),
             "  %d  ERRORS\t  %d  WARNINGS\n\n",
             _errorCount, _warningCount );
    _error.AppendToUserMsg( errbuf );
@@ -179,7 +179,7 @@ istream * STEPfile::OpenInputFile( const std::string filename ) {
    } else {
        if( SetFileName( filename ).empty() && ( filename.compare( "-" ) != 0 ) ) {
            char msg[BUFSIZ+1];
-            sprintf( msg, "Unable to find file for input: \'%s\'. File not read.\n", filename.c_str() );
+            snprintf( msg, sizeof(msg), "Unable to find file for input: \'%s\'. File not read.\n", filename.c_str() );
            _error.AppendToUserMsg( msg );
            _error.GreaterSeverity( SEVERITY_INPUT_ERROR );
            return( 0 );
@@ -196,7 +196,7 @@ istream * STEPfile::OpenInputFile( const std::string filename ) {

    if( !in || !( in -> good() ) ) {
        char msg[BUFSIZ+1];
-        sprintf( msg, "Unable to open file for input: \'%s\'. File not read.\n", filename.c_str() );
+        snprintf( msg, sizeof(msg), "Unable to open file for input: \'%s\'. File not read.\n", filename.c_str() );
        _error.AppendToUserMsg( msg );
        _error.GreaterSeverity( SEVERITY_INPUT_ERROR );
        return ( 0 );
@@ -231,7 +231,7 @@ ofstream * STEPfile::OpenOutputFile( std::string filename ) {
    } else {
        if( SetFileName( filename ).empty() ) {
            char msg[BUFSIZ+1];
-            sprintf( msg, "can't find file: %s\nFile not written.\n", filename.c_str() );
+            snprintf( msg, sizeof(msg), "can't find file: %s\nFile not written.\n", filename.c_str() );
            _error.AppendToUserMsg( msg );
            _error.GreaterSeverity( SEVERITY_INPUT_ERROR );
        }
@@ -2,6 +2,7 @@ set(LAZY_SRCS
  lazyDataSectionReader.cc
  lazyFileReader.cc
  lazyInstMgr.cc
+  lazySupport.cc
  p21HeaderSectionReader.cc
  sectionReader.cc
  lazyP21DataSectionReader.cc
@@ -13,22 +14,27 @@ include_directories(
  ${CMAKE_SOURCE_DIR}/include/stepcode
  )

-set(_libdeps stepcore stepdai steputils stepeditor)
+

 if(BUILD_SHARED_LIBS)
+  set(_libdeps stepcore stepdai steputils stepeditor)
  SC_ADDLIB(steplazyfile SHARED SOURCES ${LAZY_SRCS} LINK_LIBRARIES ${_libdeps})
  if(WIN32)
    target_compile_definitions(steplazyfile PRIVATE SC_LAZYFILE_DLL_EXPORTS)
  endif()
+  SC_ADDEXEC(lazy_test SOURCES "lazy_test.cc;sc_benchmark.cc" LINK_LIBRARIES steplazyfile stepeditor ${_libdeps} NO_INSTALL)
+  target_compile_definitions(lazy_test PRIVATE NO_REGISTRY)
 endif()

 if(BUILD_STATIC_LIBS)
  set(_libdeps stepcore-static stepdai-static steputils-static stepeditor-static)
  SC_ADDLIB(steplazyfile-static STATIC SOURCES ${LAZY_SRCS} LINK_LIBRARIES ${_libdeps})
+  if(NOT BUILD_SHARED_LIBS)
+    SC_ADDEXEC(lazy_test SOURCES "lazy_test.cc;sc_benchmark.cc" LINK_LIBRARIES steplazyfile-static stepeditor-static ${_libdeps} NO_INSTALL)
+    target_compile_definitions(lazy_test PRIVATE NO_REGISTRY)
+  endif()
 endif()

-SC_ADDEXEC(lazy_test SOURCES "lazy_test.cc;sc_benchmark.cc" LINK_LIBRARIES steplazyfile stepeditor NO_INSTALL)
-target_compile_definitions(lazy_test PRIVATE NO_REGISTRY)

 # Local Variables:
 # tab-width: 8
@@ -37,3 +43,17 @@ target_compile_definitions(lazy_test PRIVATE NO_REGISTRY)
 # End:
 # ex: shiftwidth=2 tabstop=8

+if(SC_ENABLE_TESTING)
+  if(BUILD_SHARED_LIBS)
+    set(_lazy_index_libs steplazyfile stepeditor stepcore stepdai steputils)
+  else()
+    set(_lazy_index_libs steplazyfile-static stepeditor-static
+      stepcore-static stepdai-static steputils-static)
+  endif()
+  SC_ADDEXEC(lazy_index_test SOURCES lazy_index_test.cc
+    LINK_LIBRARIES ${_lazy_index_libs} NO_INSTALL)
+  add_test(NAME lazy_index
+    COMMAND lazy_index_test
+      ${CMAKE_CURRENT_SOURCE_DIR}/test/lazy_index.stp
+      ${CMAKE_CURRENT_SOURCE_DIR}/test/lazy_scope.stp)
+endif()
@@ -65,6 +65,29 @@
 #include <string.h>
 #include <stdio.h>

+/*
+ * Judy keys are byte-packed: adjacent slots may start at an address that is
+ * not suitably aligned for judyvalue.  Callers are likewise permitted to
+ * supply byte buffers without judyvalue alignment.  Copy through an aligned
+ * local value rather than dereferencing a cast pointer.  Zero-filling any
+ * bytes not requested also makes partial loads deterministic.
+ */
+static judyvalue
+judy_load_value( const unsigned char * source, unsigned int size )
+{
+    judyvalue value = 0;
+
+    memcpy( &value, source, size );
+    return value;
+}
+
+static void
+judy_store_value( unsigned char * destination, judyvalue value,
+                  unsigned int size )
+{
+    memcpy( destination, &value, size );
+}
+
 #if defined(STANDALONE) || defined(ASKITIS)

 extern unsigned int MaxMem;
@@ -313,7 +336,6 @@ void judy_free( Judy * judy, void * block, int type ) {
 //    assemble key from current path

 unsigned int judy_key( Judy * judy, unsigned char * buff, unsigned int max ) {
-    judyvalue * dest = ( judyvalue * )buff;
    unsigned int len = 0, idx = 0, depth;
    int slot, off, type;
    judyvalue value;
@@ -333,7 +355,8 @@ unsigned int judy_key( Judy * judy, unsigned char * buff, unsigned int max ) {

        if( judy->depth )
            if( !( len & JUDY_key_mask ) ) {
-                dest[depth] = 0;
+                judy_store_value( buff + depth * JUDY_key_size, 0,
+                                  JUDY_key_size );
            }

        switch( type ) {
@@ -350,9 +373,14 @@ unsigned int judy_key( Judy * judy, unsigned char * buff, unsigned int max ) {
                base = ( unsigned char * )( judy->stack[idx].next & JUDY_mask );

                if( judy->depth ) {
-                    value = *( judyvalue * )( base + slot * keysize );
+                    value = judy_load_value( base + slot * keysize,
+                                             JUDY_key_size );
                    value &= JudyMask[keysize];
-                    dest[depth++] |= value;
+                    value |= judy_load_value( buff + depth * JUDY_key_size,
+                                              JUDY_key_size );
+                    judy_store_value( buff + depth * JUDY_key_size, value,
+                                      JUDY_key_size );
+                    depth++;
                    len += keysize;

                    if( depth < judy->depth ) {
@@ -383,7 +411,13 @@ unsigned int judy_key( Judy * judy, unsigned char * buff, unsigned int max ) {

            case JUDY_radix:
                if( judy->depth ) {
-                    dest[depth] |= ( judyvalue )slot << ( JUDY_key_size - ( ++len & JUDY_key_mask ) ) * 8;
+                    value = judy_load_value( buff + depth * JUDY_key_size,
+                                             JUDY_key_size );
+                    value |= ( judyvalue )slot <<
+                             ( ( JUDY_key_size - ++len ) &
+                               JUDY_key_mask ) * 8;
+                    judy_store_value( buff + depth * JUDY_key_size, value,
+                                      JUDY_key_size );
                    if( !( len & JUDY_key_mask ) ) {
                        depth++;
                    }
@@ -419,7 +453,6 @@ unsigned int judy_key( Judy * judy, unsigned char * buff, unsigned int max ) {
 //    find slot & setup cursor

 JudySlot * judy_slot( Judy * judy, const unsigned char * buff, unsigned int max ) {
-    judyvalue * src = ( judyvalue * )buff;
    int slot, size, keysize, tst, cnt;
    JudySlot next = *judy->root;
    judyvalue value, test = 0;
@@ -463,7 +496,9 @@ JudySlot * judy_slot( Judy * judy, const unsigned char * buff, unsigned int max
                value = 0;

                if( judy->depth ) {
-                    value = src[depth++];
+                    value = judy_load_value( buff + depth * JUDY_key_size,
+                                             JUDY_key_size );
+                    depth++;
                    off |= JUDY_key_mask;
                    off++;
                    value &= JudyMask[keysize];
@@ -478,7 +513,8 @@ JudySlot * judy_slot( Judy * judy, const unsigned char * buff, unsigned int max
                //  find slot > key

                while( slot-- ) {
-                    test = *( judyvalue * )( base + slot * keysize );
+                    test = judy_load_value( base + slot * keysize,
+                                            JUDY_key_size );
 #if BYTE_ORDER == BIG_ENDIAN
                    test >>= 8 * ( JUDY_key_size - keysize );
 #else
@@ -509,7 +545,9 @@ JudySlot * judy_slot( Judy * judy, const unsigned char * buff, unsigned int max
                table = ( JudySlot * )( next & JUDY_mask ); // outer radix

                if( judy->depth ) {
-                    slot = ( src[depth] >> ( (( JUDY_key_size - ++off) & JUDY_key_mask ) * 8 ) ) & 0xff;
+                    value = judy_load_value( buff + depth * JUDY_key_size,
+                                             JUDY_key_size );
+                    slot = ( value >> ( (( JUDY_key_size - ++off) & JUDY_key_mask ) * 8 ) ) & 0xff;
                } else if( off < max ) {
                    slot = buff[off++];
                } else {
@@ -1224,10 +1262,9 @@ void judy_splitspan( Judy * judy, JudySlot * next, unsigned char * base ) {
 //    judy_cell: add string to judy array

 JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max ) {
-    judyvalue * src = ( judyvalue * )buff;
    int size, idx, slot, cnt, tst;
    JudySlot * next = judy->root;
-    judyvalue test, value;
+    judyvalue test = 0, value;
    unsigned int off = 0, start;
    JudySlot * table;
    JudySlot * node;
@@ -1261,7 +1298,9 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max
                value = 0;

                if( judy->depth ) {
-                    value = src[depth++];
+                    value = judy_load_value( buff + depth * JUDY_key_size,
+                                             JUDY_key_size );
+                    depth++;
                    off |= JUDY_key_mask;
                    off++;
                    value &= JudyMask[keysize];
@@ -1276,7 +1315,8 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max
                //  find slot > key

                while( slot-- ) {
-                    test = *( judyvalue * )( base + slot * keysize );
+                    test = judy_load_value( base + slot * keysize,
+                                            JUDY_key_size );
 #if BYTE_ORDER == BIG_ENDIAN
                    test >>= 8 * ( JUDY_key_size - keysize );
 #else
@@ -1378,7 +1418,9 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max
                table = ( JudySlot * )( *next & JUDY_mask ); // outer radix

                if( judy->depth ) {
-                    slot = ( src[depth] >> ( ( (JUDY_key_size - ++off) & JUDY_key_mask ) * 8 ) ) & 0xff;
+                    value = judy_load_value( buff + depth * JUDY_key_size,
+                                             JUDY_key_size );
+                    slot = ( value >> ( ( (JUDY_key_size - ++off) & JUDY_key_mask ) * 8 ) ) & 0xff;
                } else if( off < max ) {
                    slot = buff[off++];
                } else {
@@ -1464,7 +1506,8 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max
            //    fill in slot 0 with bytes of key

            if( judy->depth ) {
-                value = src[depth];
+                value = judy_load_value( buff + depth * JUDY_key_size,
+                                         JUDY_key_size );
 #if BYTE_ORDER != BIG_ENDIAN
                memcpy( base, &value, keysize );  // copy new key into slot
 #else
@@ -1542,7 +1585,9 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max

            //    fill in slot 0 with bytes of key

-            *( judyvalue * )base = src[depth];
+            value = judy_load_value( buff + depth * JUDY_key_size,
+                                     JUDY_key_size );
+            judy_store_value( base, value, JUDY_key_size );

            if( judy->level < judy->max ) {
                judy->level++;
@@ -1562,4 +1607,3 @@ JudySlot * judy_cell( Judy * judy, const unsigned char * buff, unsigned int max
 #endif
    return next;
 }
-
@@ -6,7 +6,7 @@
 lazyDataSectionReader::lazyDataSectionReader( lazyFileReader * parent, std::ifstream & file,
        std::streampos start, sectionID sid ):
    sectionReader( parent, file, start, sid ) {
-    _sectionIdentifier = ""; //FIXME set _sectionIdentifier from the data section identifier (2002 rev of Part 21), if present
+    _sectionIdentifier = ""; //FIXME retain the data section identifier (2002 revision of Part 21)
    _error = false;
+    _completelyLoaded = false;
 }
-
@@ -19,20 +19,44 @@ void lazyFileReader::initP21() {
        }
        _parent->registerDataSection( r );

+        if( _parent->cancelled() ) break;
+
        //check for new data section (DATA) or end of file (END-ISO-10303-21;)
-        while( isspace( _file.peek() ) && _file.good() ) {
-            _file.ignore( 1 );
+        for( ;; ) {
+            while( isspace( _file.peek() ) && _file.good() ) _file.ignore( 1 );
+            if( _file.peek() != '/' ) break;
+            std::streampos comment = _file.tellg();
+            _file.get();
+            if( _file.peek() != '*' ) {
+                _file.seekg( comment );
+                break;
+            }
+            _file.get();
+            int previous = 0;
+            int current = 0;
+            while( _file.good() ) {
+                current = _file.get();
+                if( previous == '*' && current == '/' ) break;
+                previous = current;
+            }
        }
+        std::streampos nextSection = _file.tellg();
        if( needKW( "END-ISO-10303-21;" ) ) {
            break;
-        } else if( !needKW( "DATA" ) ) {
+        }
+        _file.clear();
+        _file.seekg( nextSection );
+        if( !needKW( "DATA" ) ) {
            std::cerr << "Corrupted file - did not find new data section (\"DATA\") or end of file (\"END-ISO-10303-21;\") at offset " << _file.tellg() << std::endl;
            break;
        }
+        _file.clear();
+        _file.seekg( nextSection );
    }
 }

 bool lazyFileReader::needKW( const char * kw ) {
+    std::streampos start = _file.tellg();
    const char * c = kw;
    bool found = true;
    while( *c ) {
@@ -42,6 +66,10 @@ bool lazyFileReader::needKW( const char * kw ) {
        }
        c++;
    }
+    if( !found ) {
+        _file.clear();
+        _file.seekg( start );
+    }
    return found;
 }

@@ -49,11 +77,26 @@ instancesLoaded_t * lazyFileReader::getHeaderInstances() {
    return _header->getInstances();
 }

-lazyFileReader::lazyFileReader( std::string fname, lazyInstMgr * i, fileID fid ): _fileName( fname ), _parent( i ), _fileID( fid ) {
+lazyFileReader::lazyFileReader( std::string fname, lazyInstMgr * i, fileID fid ): _fileName( fname ), _parent( i ),
+        _header( 0 ), _schemaWarningClaimed( false ), _fileID( fid ),
+        _fileSize( 0 ), _valid( false ) {
    _file.open( _fileName.c_str(), std::ios::binary );
    _file.imbue( std::locale::classic() );
    _file.unsetf( std::ios_base::skipws );
-    assert( _file.is_open() && _file.good() );
+    if( !_file.is_open() || !_file.good() ) {
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_FATAL;
+        diagnostic.message = "unable to open exchange file: " + _fileName;
+        _parent->emitDiagnostic( diagnostic );
+        return;
+    }
+
+    _file.seekg( 0, std::ios::end );
+    std::streampos end = _file.tellg();
+    if( end != std::streampos( -1 ) ) {
+        _fileSize = static_cast<lazyFileOffset>( static_cast<std::streamoff>( end ) );
+    }
+    _file.seekg( 0, std::ios::beg );

    detectType();
    switch( _fileType ) {
@@ -67,9 +110,9 @@ lazyFileReader::lazyFileReader( std::string fname, lazyInstMgr * i, fileID fid )
            std::cerr << "Reached default case, " << __FILE__ << ":" << __LINE__ << std::endl;
            abort();
    }
+    _valid = true;
 }

 lazyFileReader::~lazyFileReader() {
    delete _header;
 }
-
@@ -8,22 +8,35 @@

 #include "clstepcore/sdaiApplication_instance.h"

+#include <algorithm>
+#include <climits>
+#include <sstream>
+
 lazyInstMgr::lazyInstMgr() {
    _headerRegistry = new Registry( HeaderSchemaInit );
    _instanceTypes = new instanceTypes_t( 255 ); //NOTE arbitrary max of 255 chars for a type name
    _lazyInstanceCount = 0;
    _loadedInstanceCount = 0;
+    _cacheHighWater = 0;
+    _cacheHits = 0;
+    _cacheMisses = 0;
+    _materializations = 0;
+    _evictions = 0;
+    _activeBatches = 0;
+    _residentSourceBytes = 0;
+    _sourceBytesHighWater = 0;
+    _batchLoadDepth = 0;
+    _cancelled = false;
    _longestTypeNameLen = 0;
    _mainRegistry = 0;
+    _ownsMainRegistry = false;
    _errors = new ErrorDescriptor();
    _ima = new instMgrAdapter( this );
 }

 lazyInstMgr::~lazyInstMgr() {
-    delete _headerRegistry;
-    delete _errors;
-    delete _ima;
-    //loop over files, sections, instances; delete header instances
+    // Keep registries and the adapter alive until their instances are gone.
+    _instancesLoaded.clear( true );
    lazyFileReaderVec_t::iterator fit = _files.begin();
    for( ; fit != _files.end(); ++fit ) {
        delete *fit;
@@ -32,8 +45,12 @@ lazyInstMgr::~lazyInstMgr() {
    for( ; sit != _dataSections.end(); ++sit ) {
        delete *sit;
    }
-    _instancesLoaded.clear();
    _instanceStreamPos.clear();
+    delete _instanceTypes;
+    delete _ima;
+    if( _ownsMainRegistry ) delete _mainRegistry;
+    delete _headerRegistry;
+    delete _errors;
 }

 sectionID lazyInstMgr::registerDataSection( lazyDataSectionReader * sreader ) {
@@ -44,24 +61,44 @@ sectionID lazyInstMgr::registerDataSection( lazyDataSectionReader * sreader ) {
 void lazyInstMgr::addLazyInstance( namedLazyInstance inst ) {
    _lazyInstanceCount++;
    assert( inst.loc.begin > 0 && inst.loc.instance > 0 );
+    const bool duplicate = _instanceStreamPos.find( inst.loc.instance ) != 0;
    int len = strlen( inst.name );
    if( len > _longestTypeNameLen ) {
        _longestTypeNameLen = len;
        _longestTypeName = inst.name;
    }
    _instanceTypes->insert( inst.name, inst.loc.instance );
-    /* store 16 bits of section id and 48 of instance offset into one 64-bit int
-    ** TODO: check and warn if anything is lost (in calling code?)
-    ** does 32bit need anything special?
-    **
-    ** create conversion class?
-    **  could then initialize conversion object with number of bits
-    **  also a good place to check for data loss
-    */
-    positionAndSection ps = inst.loc.section;
-    ps <<= 48;
-    ps |= ( inst.loc.begin & 0xFFFFFFFFFFFFULL );
-    _instanceStreamPos.insert( inst.loc.instance, ps );
+    if( inst.componentTypes ) {
+        if( !duplicate && !inst.componentTypes->empty() ) {
+            _instanceComponentTypes[inst.loc.instance] = *inst.componentTypes;
+        }
+        std::vector<std::string>::const_iterator type = inst.componentTypes->begin();
+        for( ; type != inst.componentTypes->end(); ++type ) {
+            _instanceTypes->insert( type->c_str(), inst.loc.instance );
+            if( static_cast<int>( type->size() ) > _longestTypeNameLen ) {
+                _longestTypeNameLen = type->size();
+                _longestTypeName = *type;
+            }
+        }
+        delete inst.componentTypes;
+    }
+    if( !duplicate ) _allInstances.push_back( inst.loc.instance );
+    instancePosition pos;
+    pos.begin = inst.loc.begin;
+    pos.section = inst.loc.section;
+    if( duplicate ) {
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_WARNING;
+        diagnostic.entity = inst.loc.instance;
+        diagnostic.type = inst.name;
+        diagnostic.offset = inst.loc.begin;
+        diagnostic.message = "duplicate instance identifier";
+        emitDiagnostic( diagnostic );
+    }
+    _instanceStreamPos.insert( inst.loc.instance, pos );
+    if( !duplicate && inst.loc.end >= inst.loc.begin ) {
+        _instanceSourceBytes[inst.loc.instance] = inst.loc.end - inst.loc.begin;
+    }

    if( inst.refs ) {
        if( inst.refs->size() > 0 ) {
@@ -72,10 +109,103 @@ void lazyInstMgr::addLazyInstance( namedLazyInstance inst ) {
                //reverse refs
                _revInstanceRefs.insert( *it, inst.loc.instance );
            }
-        } else {
-            delete inst.refs;
+        }
+        delete inst.refs;
+    }
+}
+
+const std::vector<std::string> & lazyInstMgr::componentTypes( instanceID id ) const {
+    static const std::vector<std::string> empty;
+    std::map<instanceID, std::vector<std::string> >::const_iterator found =
+        _instanceComponentTypes.find( id );
+    return found == _instanceComponentTypes.end() ? empty : found->second;
+}
+
+LazyInstanceIdView lazyInstMgr::instancesByType( std::string type, bool caseSensitive ) {
+    if( !caseSensitive ) {
+        std::string::iterator it = type.begin();
+        for( ; it != type.end(); ++it ) {
+            *it = static_cast<char>( toupper( static_cast<unsigned char>( *it ) ) );
        }
    }
+    return LazyInstanceIdView( _instanceTypes->find( type.c_str() ) );
+}
+
+LazyInstanceIdView lazyInstMgr::forwardReferences( instanceID id ) {
+    return LazyInstanceIdView( _fwdInstanceRefs.find( id ) );
+}
+
+LazyInstanceIdView lazyInstMgr::reverseReferences( instanceID id ) {
+    return LazyInstanceIdView( _revInstanceRefs.find( id ) );
+}
+
+std::string lazyInstMgr::sourceRecord( instanceID id ) {
+    instanceStreamPos_t::cvector * positions = _instanceStreamPos.find( id );
+    std::map<instanceID, uint64_t>::const_iterator bytes = _instanceSourceBytes.find( id );
+    if( !positions || positions->size() != 1 || bytes == _instanceSourceBytes.end() ||
+            bytes->second == 0 ) {
+        return std::string();
+    }
+    const instancePosition & position = positions->front();
+    if( position.section >= _dataSections.size() || !_dataSections[position.section] ) {
+        return std::string();
+    }
+    return _dataSections[position.section]->sourceRecord( position.begin, bytes->second );
+}
+
+void lazyInstMgr::observeScan( fileID file, lazyFileOffset offset, lazyFileOffset fileSize ) {
+    if( _cancelled ) return;
+    if( _cancellationCallback && _cancellationCallback() ) {
+        _cancelled = true;
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_INFO;
+        diagnostic.offset = offset;
+        diagnostic.message = "scan cancelled";
+        emitDiagnostic( diagnostic );
+        return;
+    }
+    if( _progressCallback && ( _lazyInstanceCount == 1 || ( _lazyInstanceCount % 4096 ) == 0 || offset >= fileSize ) ) {
+        LazyScanProgress progress;
+        progress.file = file;
+        progress.offset = offset;
+        progress.fileSize = fileSize;
+        progress.instancesScanned = _lazyInstanceCount;
+        _progressCallback( progress );
+    }
+}
+
+void lazyInstMgr::emitDiagnostic( LazyDiagnostic diagnostic ) {
+    std::ostringstream key;
+    key << diagnostic.type << '#' << diagnostic.entity << ':' << diagnostic.attribute << ':' << diagnostic.message;
+    uint64_t & count = _diagnosticCounts[key.str()];
+    ++count;
+    diagnostic.occurrences = count;
+    if( _diagnosticCallback && count == 1 ) {
+        _diagnosticCallback( diagnostic );
+    }
+}
+
+uint64_t lazyInstMgr::diagnosticCount( const std::string & key ) const {
+    std::map<std::string, uint64_t>::const_iterator found = _diagnosticCounts.find( key );
+    return found == _diagnosticCounts.end() ? 0 : found->second;
+}
+
+LazyCacheStatistics lazyInstMgr::cacheStatistics() const {
+    LazyCacheStatistics stats;
+    stats.instancesScanned = _lazyInstanceCount;
+    stats.instancesLoaded = _loadedInstanceCount;
+    stats.instancesPinned = _pinCounts.size();
+    stats.cacheHighWater = _cacheHighWater;
+    stats.cacheHits = _cacheHits;
+    stats.cacheMisses = _cacheMisses;
+    stats.materializations = _materializations;
+    stats.evictions = _evictions;
+    stats.activeBatches = _activeBatches;
+    stats.dataSections = _dataSections.size();
+    stats.residentSourceBytes = _residentSourceBytes;
+    stats.sourceBytesHighWater = _sourceBytesHighWater;
+    stats.cancelled = _cancelled;
+    return stats;
 }

 unsigned long lazyInstMgr::getNumTypes() const {
@@ -93,7 +223,7 @@ unsigned long lazyInstMgr::getNumTypes() const {
    return n ;
 }

-void lazyInstMgr::openFile( std::string fname ) {
+bool lazyInstMgr::openFile( std::string fname ) {
    //don't want to hold a lock for the entire time we're reading the file.
    //create a place in the vector and remember its location, then free lock
    ///FIXME begin atomic op
@@ -101,58 +231,304 @@ void lazyInstMgr::openFile( std::string fname ) {
    _files.push_back( (lazyFileReader * ) 0 );
    ///FIXME end atomic op
    lazyFileReader * lfr = new lazyFileReader( fname, this, i );
+    if( !lfr->valid() ) {
+        delete lfr;
+        _files.pop_back();
+        return false;
+    }
    _files[i] = lfr;
+    validateReferences();
    /// TODO resolve inverse attr references
    //between instances, or eDesc --> inst????
+    return true;
 }

-SDAI_Application_instance * lazyInstMgr::loadInstance( instanceID id, bool reSeek ) {
+void lazyInstMgr::validateReferences() {
+    instanceRefs_t::cpair current = _fwdInstanceRefs.begin();
+    while( current.value ) {
+        instanceRefs_t::cvector::const_iterator ref = current.value->begin();
+        for( ; ref != current.value->end(); ++ref ) {
+            if( !_instanceStreamPos.find( *ref ) ) {
+                LazyDiagnostic diagnostic;
+                diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+                diagnostic.entity = current.key;
+                const char * type = typeFromFile( current.key );
+                if( type ) diagnostic.type = type;
+                instanceStreamPos_t::cvector * positions = _instanceStreamPos.find( current.key );
+                if( positions && !positions->empty() ) diagnostic.offset = positions->front().begin;
+                std::ostringstream message;
+                message << "reference to missing instance #" << *ref;
+                diagnostic.message = message.str();
+                emitDiagnostic( diagnostic );
+            }
+        }
+        current = _fwdInstanceRefs.next();
+    }
+}
+
+SDAI_Application_instance * lazyInstMgr::loadInstance( instanceID id, bool reSeek, bool promoteCached ) {
+    if( _batchLoadDepth && ( _cancelled ||
+            ( _cancellationCallback && _cancellationCallback() ) ) ) {
+        _cancelled = true;
+        return 0;
+    }
    assert( _mainRegistry && "Main registry has not been initialized. Do so with initRegistry() or setRegistry()." );
    std::streampos oldPos;
-    positionAndSection ps;
-    sectionID sid;
+    instancePosition pos = instancePosition();
    SDAI_Application_instance * inst = _instancesLoaded.find( id );
    if( inst ) {
+        ++_cacheHits;
+        if( promoteCached && _batchLoadDepth == 0 ) _permanentlyLoadedInstances.insert( id );
        return inst;
    }
+    ++_cacheMisses;
+    if( id > static_cast<instanceID>( INT_MAX ) ) {
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+        diagnostic.entity = id;
+        diagnostic.message = "instance ID exceeds the current SDAI materialization limit";
+        emitDiagnostic( diagnostic );
+        return 0;
+    }
+    const std::pair<std::set<instanceID>::iterator, bool> loading_result = _instancesLoading.insert( id );
+    if( !loading_result.second ) {
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+        diagnostic.entity = id;
+        const char * type = typeFromFile( id );
+        if( type ) diagnostic.type = type;
+        instanceStreamPos_t::cvector * positions = _instanceStreamPos.find( id );
+        if( positions && !positions->empty() ) {
+            diagnostic.offset = positions->front().begin;
+        }
+        diagnostic.message = "cyclic dependency encountered while materializing instance";
+        emitDiagnostic( diagnostic );
+        return 0;
+    }
+    /* sectionReader materializes referenced instances recursively.  Keep an
+     * explicit in-progress set because an instance is not cacheable until its
+     * STEPread() has completed. */
+    class LoadingGuard {
+      public:
+        LoadingGuard( std::set<instanceID> & loading, instanceID id )
+            : _loading( loading ), _id( id ), _active( true ) {}
+        ~LoadingGuard() { release(); }
+        void release() {
+            if( _active ) {
+                _loading.erase( _id );
+                _active = false;
+            }
+        }
+      private:
+        std::set<instanceID> & _loading;
+        instanceID _id;
+        bool _active;
+    } loading_guard( _instancesLoading, id );
    instanceStreamPos_t::cvector * cv;
    if( 0 != ( cv = _instanceStreamPos.find( id ) ) ) {
        switch( cv->size() ) {
            case 0:
-                std::cerr << "Instance #" << id << " not found in any section." << std::endl;
+                if( !_diagnosticCallback ) {
+                    std::cerr << "Instance #" << id
+                        << " not found in any section." << std::endl;
+                }
                break;
            case 1:
-                long int off;
-                ps = cv->at( 0 );
-                off = ps & 0xFFFFFFFFFFFFULL;
-                sid = ps >> 48;
-                assert( _dataSections.size() > sid );
+                pos = cv->at( 0 );
+                assert( _dataSections.size() > pos.section );
                if( reSeek ) {
-                    oldPos = _dataSections[sid]->tellg();
+                    oldPos = _dataSections[pos.section]->tellg();
                }
-                inst = _dataSections[sid]->getRealInstance( _mainRegistry, off, id );
+                inst = _dataSections[pos.section]->getRealInstance( _mainRegistry, pos.begin, id );
                if( reSeek ) {
-                    _dataSections[sid]->seekg( oldPos );
+                    _dataSections[pos.section]->seekg( oldPos );
+                }
+                /* A recursive reference load may observe cancellation after
+                 * this instance began materializing.  Never cache that
+                 * partially resolved SDAI object. */
+                if( _batchLoadDepth && ( _cancelled ||
+                        ( _cancellationCallback && _cancellationCallback() ) ) ) {
+                    _cancelled = true;
+                    if( !isNilSTEPentity( inst ) ) delete inst;
+                    inst = 0;
                }
                break;
            default:
-                std::cerr << "Instance #" << id << " exists in multiple sections. This is not yet supported." << std::endl;
+                if( !_diagnosticCallback ) {
+                    std::cerr << "Instance #" << id
+                        << " exists in multiple sections. This is not yet supported."
+                        << std::endl;
+                }
+                {
+                    LazyDiagnostic diagnostic;
+                    diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+                    diagnostic.entity = id;
+                    diagnostic.message = "instance identifier occurs in multiple DATA sections";
+                    emitDiagnostic( diagnostic );
+                }
                break;
        }
+        /* Explicit attributes are now complete.  Inverse discovery may
+         * safely revisit this instance without tripping the materialization
+         * cycle detector. */
+        loading_guard.release();
        if( !isNilSTEPentity( inst ) ) {
            _instancesLoaded.insert( id, inst );
            _loadedInstanceCount++;
-            lazyRefs lr( this, inst );
-            lazyRefs::referentInstances_t insts = lr.result();
+            ++_materializations;
+            _cacheHighWater = std::max<uint64_t>( _cacheHighWater, _loadedInstanceCount );
+            std::map<instanceID, uint64_t>::const_iterator source_size = _instanceSourceBytes.find( id );
+            if( source_size != _instanceSourceBytes.end() ) {
+                _residentSourceBytes += source_size->second;
+                _sourceBytesHighWater = std::max<uint64_t>( _sourceBytesHighWater,
+                    _residentSourceBytes );
+            }
+            if( _batchLoadDepth ) {
+                _batchOwnedInstances.insert( id );
+            } else {
+                _permanentlyLoadedInstances.insert( id );
+                lazyRefs lr( this, inst );
+                lazyRefs::referentInstances_t insts = lr.result();
+                resolveDeferredInverses();
+            }
        } else {
-            std::cerr << "Error loading instance #" << id << "." << std::endl;
+            if( !_diagnosticCallback ) {
+                std::cerr << "Error loading instance #" << id << "."
+                    << std::endl;
+            }
+            LazyDiagnostic diagnostic;
+            diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+            diagnostic.entity = id;
+            diagnostic.offset = pos.begin;
+            diagnostic.message = "SDAI instance materialization failed";
+            emitDiagnostic( diagnostic );
        }
    } else {
-        std::cerr << "Instance #" << id << " not found in any section." << std::endl;
+        if( !_diagnosticCallback ) {
+            std::cerr << "Instance #" << id
+                << " not found in any section." << std::endl;
+        }
+        LazyDiagnostic diagnostic;
+        diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+        diagnostic.entity = id;
+        diagnostic.message = "instance not found in any DATA section";
+        emitDiagnostic( diagnostic );
    }
    return inst;
 }

+void lazyInstMgr::resolveDeferredInverses() {
+    if( !_instancesLoading.empty() ) return;
+
+    while( !_deferredInverseInstances.empty() ) {
+        std::set<instanceID> deferred;
+        deferred.swap( _deferredInverseInstances );
+        std::set<instanceID>::const_iterator id = deferred.begin();
+        for( ; id != deferred.end(); ++id ) {
+            SDAI_Application_instance * inst = cachedInstance( *id );
+            if( inst ) {
+                lazyRefs refs( this, inst );
+            }
+        }
+    }
+}
+
+SDAI_Application_instance * lazyInstMgr::cachedInstance( instanceID id ) {
+    return _instancesLoaded.find( id );
+}
+
+std::vector<instanceID> lazyInstMgr::dependencyClosure( const std::vector<instanceID> & roots ) {
+    std::set<instanceID> closure( roots.begin(), roots.end() );
+    std::vector<instanceID> queue( roots.begin(), roots.end() );
+    size_t current = 0;
+    while( current < queue.size() ) {
+        if( _cancelled || ( _cancellationCallback && _cancellationCallback() ) ) {
+            _cancelled = true;
+            break;
+        }
+        instanceRefs_t::cvector * refs = _fwdInstanceRefs.find( queue[current++] );
+        if( !refs ) continue;
+        instanceRefs_t::cvector::const_iterator ref = refs->begin();
+        for( ; ref != refs->end(); ++ref ) {
+            /* validateReferences() reports nonexistent targets when the file
+             * is opened.  They cannot be pinned or materialized, and adding
+             * them to a batch only produces a second, less useful error (or
+             * an integer-limit error for a malformed maximum-width ID). */
+            if( !_instanceStreamPos.find( *ref ) ) continue;
+            if( closure.insert( *ref ).second ) queue.push_back( *ref );
+        }
+    }
+    return std::vector<instanceID>( closure.begin(), closure.end() );
+}
+
+LazyInstanceBatch lazyInstMgr::loadBatch( instanceID root ) {
+    std::vector<instanceID> roots( 1, root );
+    return loadBatch( roots );
+}
+
+LazyInstanceBatch lazyInstMgr::loadBatch( const std::vector<instanceID> & roots ) {
+    std::vector<instanceID> closure = dependencyClosure( roots );
+    std::vector<instanceID>::const_iterator id = closure.begin();
+    for( ; id != closure.end(); ++id ) {
+        if( _cancelled || ( _cancellationCallback && _cancellationCallback() ) ) {
+            _cancelled = true;
+            closure.erase( id, closure.end() );
+            break;
+        }
+        ++_pinCounts[*id];
+    }
+    ++_activeBatches;
+    ++_batchLoadDepth;
+    for( id = closure.begin(); id != closure.end(); ++id ) {
+        if( _cancelled || ( _cancellationCallback && _cancellationCallback() ) ) {
+            _cancelled = true;
+            break;
+        }
+        if( !loadInstance( *id, true ) ) {
+            LazyDiagnostic diagnostic;
+            diagnostic.severity = LAZY_DIAGNOSTIC_ERROR;
+            diagnostic.entity = *id;
+            diagnostic.message = "dependency batch could not materialize instance";
+            emitDiagnostic( diagnostic );
+        }
+    }
+    --_batchLoadDepth;
+    return LazyInstanceBatch( this, roots, closure );
+}
+
+void lazyInstMgr::releaseBatch( const std::vector<instanceID> & instances ) {
+    std::vector<instanceID> evict;
+    std::vector<instanceID>::const_iterator id = instances.begin();
+    for( ; id != instances.end(); ++id ) {
+        std::map<instanceID, size_t>::iterator pin = _pinCounts.find( *id );
+        if( pin == _pinCounts.end() ) continue;
+        if( --pin->second == 0 ) {
+            _pinCounts.erase( pin );
+            if( _batchOwnedInstances.count( *id ) && !_permanentlyLoadedInstances.count( *id ) ) {
+                evict.push_back( *id );
+            }
+        }
+    }
+    std::vector<SDAI_Application_instance *> deleted;
+    for( id = evict.begin(); id != evict.end(); ++id ) {
+        SDAI_Application_instance * inst = _instancesLoaded.find( *id );
+        if( !inst ) continue;
+        _instancesLoaded.removeEntry( *id );
+        _batchOwnedInstances.erase( *id );
+        deleted.push_back( inst );
+        --_loadedInstanceCount;
+        std::map<instanceID, uint64_t>::const_iterator source_size = _instanceSourceBytes.find( *id );
+        if( source_size != _instanceSourceBytes.end() ) {
+            _residentSourceBytes = source_size->second <= _residentSourceBytes ?
+                _residentSourceBytes - source_size->second : 0;
+        }
+        ++_evictions;
+    }
+    std::vector<SDAI_Application_instance *>::iterator inst = deleted.begin();
+    for( ; inst != deleted.end(); ++inst ) delete *inst;
+    if( _activeBatches ) --_activeBatches;
+}
+

 instanceSet * lazyInstMgr::instanceDependencies( instanceID id ) {
    instanceSet * checkedDependencies = new instanceSet();
@@ -182,4 +558,3 @@ instanceSet * lazyInstMgr::instanceDependencies( instanceID id ) {

    return checkedDependencies;
 }
-
@@ -3,13 +3,60 @@
 #include "cllazyfile/lazyP21DataSectionReader.h"
 #include "cllazyfile/lazyInstMgr.h"

+void lazyP21DataSectionReader::findSectionStart() {
+    std::streampos keywordEnd = findNormalString( "DATA" );
+    if( keywordEnd == std::streampos( -1 ) ) {
+        _sectionStart = -1;
+        return;
+    }
+    _file.seekg( keywordEnd );
+    skipWS();
+    int depth = 0;
+    int current = _file.get();
+    if( current == ';' ) {
+        _sectionStart = _file.tellg();
+        return;
+    }
+    if( current != '(' ) {
+        _sectionStart = -1;
+        return;
+    }
+    depth = 1;
+    while( depth && _file.good() ) {
+        current = _file.get();
+        if( current == '\'' ) {
+            _file.seekg( _file.tellg() - std::streampos( 1 ) );
+            GetLiteralStr( _file, _lazyFile->getInstMgr()->getErrorDesc() );
+        } else if( current == '/' && _file.peek() == '*' ) {
+            findNormalString( "*/" );
+        } else if( current == '(' ) {
+            ++depth;
+        } else if( current == ')' ) {
+            --depth;
+        }
+    }
+    skipWS();
+    if( depth == 0 && _file.get() == ';' ) {
+        _sectionStart = _file.tellg();
+    } else {
+        _sectionStart = -1;
+    }
+}
+
 lazyP21DataSectionReader::lazyP21DataSectionReader( lazyFileReader * parent, std::ifstream & file,
        std::streampos start, sectionID sid ):
    lazyDataSectionReader( parent, file, start, sid ) {
    findSectionStart();
+    if( _sectionStart == std::streampos( -1 ) ) {
+        _error = true;
+        return;
+    }
    namedLazyInstance nl;
    while( nl = nextInstance(), ( ( nl.loc.begin > 0 ) && ( nl.name != 0 ) ) ) {
        parent->getInstMgr()->addLazyInstance( nl );
+        parent->getInstMgr()->observeScan( parent->ID(),
+            static_cast<lazyFileOffset>( static_cast<std::streamoff>( _file.tellg() ) ), parent->fileSize() );
+        if( parent->getInstMgr()->cancelled() ) return;
    }

    if(  sectionReader::_error->severity() <= SEVERITY_WARNING ) {
@@ -49,26 +96,64 @@ const namedLazyInstance lazyP21DataSectionReader::nextInstance() {
    namedLazyInstance i;

    i.refs = 0;
+    i.componentTypes = 0;
    i.loc.section = 0;
-    i.loc.begin = _file.tellg();
+    i.loc.end = 0;
+    std::streampos start = _file.tellg();
+    i.loc.begin = start == std::streampos( -1 ) ? 0 :
+        static_cast<lazyFileOffset>( static_cast<std::streamoff>( start ) );
    i.loc.instance = readInstanceNumber();
    if( ( _file.good() ) && ( i.loc.instance > 0 ) ) {
-        skipWS();
+        if( !skipTokenSeparators() ) {
+            _file.setstate( std::ios::failbit );
+        }
+        if( _file.good() && _file.peek() == '&' && !indexScope() ) {
+            _file.setstate( std::ios::failbit );
+        }
+        if( _file.good() && !skipTokenSeparators() ) {
+            _file.setstate( std::ios::failbit );
+        }
        i.loc.section = _sectionID;
-        i.name = getDelimitedKeyword( ";( /\\" );
+        if( _file.good() ) i.name = getDelimitedKeyword( ";( /\\" );
        if( _file.good() ) {
-            end = seekInstanceEnd( & i.refs );
+            if( i.name[0] == '\0' ) i.componentTypes = new std::vector<std::string>;
+            end = seekInstanceEnd( & i.refs, i.componentTypes );
+            if( end != std::streampos( -1 ) ) {
+                i.loc.end = static_cast<lazyFileOffset>( static_cast<std::streamoff>( end ) );
+            }
        }
    }
    if( ( i.loc.instance == 0 ) || ( !_file.good() ) || ( end == ( std::streampos ) - 1 ) ) {
        //invalid instance, so clear everything
        _file.seekg( i.loc.begin );
-        i.loc.begin = -1;
+        i.loc.begin = 0;
        if( i.refs ) {
            delete i.refs;
        }
+        if( i.componentTypes ) {
+            delete i.componentTypes;
+            i.componentTypes = 0;
+        }
        i.name = 0;
    }
    return i;
 }
+bool lazyP21DataSectionReader::indexScope() {
+    if( !skipTokenSeparators() || _file.get() != '&' ) return false;
+    const std::string scopeKeyword = getDelimitedKeyword( "#/(;\\" );
+    if( scopeKeyword != "SCOPE" ) return false;
+
+    bool haveInstance = false;
+    while( skipTokenSeparators() && _file.peek() == '#' ) {
+        namedLazyInstance nested = nextInstance();
+        if( nested.loc.begin == 0 || !nested.name ) return false;
+        _lazyFile->getInstMgr()->addLazyInstance( nested );
+        haveInstance = true;
+    }
+    if( !haveInstance || !skipTokenSeparators() ) return false;
+
+    const std::string endKeyword = getDelimitedKeyword( "/#(;\\" );
+    if( endKeyword != "ENDSCOPE" ) return false;
+    return skipScopeExportList();
+}

@@ -87,6 +87,16 @@ class SC_LAZYFILE_EXPORT lazyRefs {
            }
            //3c - for each item in both _refMap and edL, add it to _referentInstances
            potentialReferentInsts( edL );
+            /* Do not partially populate an inverse attribute and then repeat
+             * the whole pass.  A referrer that is still being parsed cannot
+             * be inspected reliably, so defer this instance as a unit. */
+            referentInstances_t::const_iterator pending = _referentInstances.begin();
+            for( ; pending != _referentInstances.end(); ++pending ) {
+                if( _lim->isMaterializing( *pending ) ) {
+                    _lim->deferInverseResolution( _id );
+                    return;
+                }
+            }
            //3d - load each inst
            iAstruct ias = invAttr( _inst, ia );
            referentInstances_t::iterator insts = _referentInstances.begin();
@@ -98,7 +108,12 @@ class SC_LAZYFILE_EXPORT lazyRefs {

        void loadInstIFFreferent( instanceID inst, iAstruct ias, const Inverse_attribute * ia ) {
            bool prevLoaded = _lim->isLoaded( inst );
+            if( _lim->isMaterializing( inst ) ) {
+                _lim->deferInverseResolution( _id );
+                return;
+            }
            SDAI_Application_instance * rinst = _lim->loadInstance( inst );
+            if( !rinst ) return;
            bool ref = refersToCurrentInst( ia, rinst );
            if( ref ) {
                if( ia->inverted_attr_()->IsAggrType() ) {
@@ -108,8 +123,16 @@ class SC_LAZYFILE_EXPORT lazyRefs {
                        assert( invAttr( _inst, ia ).a == ias.a );
                    }
                    EntityAggregate * ea = ias.a;
-                    //TODO check if duplicate
-                    ea->AddNode( new EntityNode( rinst ) );
+                    bool duplicate = false;
+                    EntityNode * existing = static_cast<EntityNode *>( ea->GetHead() );
+                    while( existing ) {
+                        if( existing->node == rinst ) {
+                            duplicate = true;
+                            break;
+                        }
+                        existing = static_cast<EntityNode *>( existing->NextNode() );
+                    }
+                    if( !duplicate ) ea->AddNode( new EntityNode( rinst ) );
                } else {
                    SDAI_Application_instance * ai = ias.i;
                    if( !ai ) {
@@ -131,8 +154,10 @@ class SC_LAZYFILE_EXPORT lazyRefs {

        ///3e - check if actually inverse ref
        bool refersToCurrentInst( const Inverse_attribute * ia, SDAI_Application_instance * referrer ) {
+            if( !referrer ) return false;
            //find the attr
            int rindex = attrIndex( referrer, ia->_inverted_attr_id, ia->_inverted_entity_id );
+            if( rindex < 0 ) return false;
            STEPattribute sa = referrer->attributes[ rindex ];
            assert( sa.getADesc()->BaseType() == ENTITY_TYPE );
            bool found = false;
@@ -279,7 +304,7 @@ class SC_LAZYFILE_EXPORT lazyRefs {


            // 1. find inverse attrs with recursion
-            getInverseAttrs( ai->eDesc, _iaList );
+            getInverseAttrs( _inst->eDesc, _iaList );

            //2. find reverse refs, map id to type (stop if there are no inverse attrs or no refs)
            if( _iaList.size() == 0 || !mapRefsToTypes() ) {
@@ -0,0 +1,106 @@
+#include <stdexcept>
+#include <utility>
+#include <ostream>
+
+#include "cllazyfile/lazySupport.h"
+#include "cllazyfile/lazyInstMgr.h"
+
+namespace {
+const instanceRefs & emptyIds() {
+    static const instanceRefs ids;
+    return ids;
+}
+}
+
+LazyInstanceIdView::const_iterator LazyInstanceIdView::begin() const {
+    return _ids ? _ids->begin() : emptyIds().begin();
+}
+
+LazyInstanceIdView::const_iterator LazyInstanceIdView::end() const {
+    return _ids ? _ids->end() : emptyIds().end();
+}
+
+size_t LazyInstanceIdView::size() const {
+    return _ids ? _ids->size() : 0;
+}
+
+bool LazyInstanceIdView::empty() const {
+    return size() == 0;
+}
+
+instanceID LazyInstanceIdView::operator[]( size_t index ) const {
+    if( !_ids || index >= _ids->size() ) {
+        throw std::out_of_range( "LazyInstanceIdView index" );
+    }
+    return ( *_ids )[index];
+}
+
+LazyInstanceBatch::LazyInstanceBatch(): _manager( 0 ) {}
+
+LazyInstanceBatch::LazyInstanceBatch( lazyInstMgr * manager,
+        const std::vector<instanceID> & roots, const std::vector<instanceID> & instances ):
+    _manager( manager ), _roots( roots ), _instances( instances ) {}
+
+LazyInstanceBatch::~LazyInstanceBatch() {
+    release();
+}
+
+LazyInstanceBatch::LazyInstanceBatch( LazyInstanceBatch && other ):
+    _manager( other._manager ), _roots( std::move( other._roots ) ),
+    _instances( std::move( other._instances ) ) {
+    other._manager = 0;
+}
+
+LazyInstanceBatch & LazyInstanceBatch::operator=( LazyInstanceBatch && other ) {
+    if( this != &other ) {
+        release();
+        _manager = other._manager;
+        _roots = std::move( other._roots );
+        _instances = std::move( other._instances );
+        other._manager = 0;
+    }
+    return *this;
+}
+
+bool LazyInstanceBatch::valid() const {
+    return _manager != 0;
+}
+
+void LazyInstanceBatch::release() {
+    if( _manager ) {
+        _manager->releaseBatch( _instances );
+        _manager = 0;
+    }
+    _roots.clear();
+    _instances.clear();
+}
+
+const std::vector<instanceID> & LazyInstanceBatch::roots() const {
+    return _roots;
+}
+
+const std::vector<instanceID> & LazyInstanceBatch::instances() const {
+    return _instances;
+}
+
+SDAI_Application_instance * LazyInstanceBatch::get( instanceID id ) const {
+    return _manager ? _manager->cachedInstance( id ) : 0;
+}
+
+LazyTextDiagnosticAdapter::LazyTextDiagnosticAdapter( std::ostream & stream ): _stream( &stream ) {}
+
+void LazyTextDiagnosticAdapter::operator()( const LazyDiagnostic & diagnostic ) const {
+    const char * label = "info";
+    if( diagnostic.severity == LAZY_DIAGNOSTIC_WARNING ) label = "warning";
+    if( diagnostic.severity == LAZY_DIAGNOSTIC_ERROR ) label = "error";
+    if( diagnostic.severity == LAZY_DIAGNOSTIC_FATAL ) label = "fatal";
+    ( *_stream ) << label;
+    if( diagnostic.entity ) ( *_stream ) << " #" << diagnostic.entity;
+    if( !diagnostic.type.empty() ) ( *_stream ) << " " << diagnostic.type;
+    if( diagnostic.offset ) ( *_stream ) << " at offset " << diagnostic.offset;
+    if( diagnostic.line ) ( *_stream ) << " line " << diagnostic.line;
+    if( !diagnostic.attribute.empty() ) ( *_stream ) << " attribute " << diagnostic.attribute;
+    ( *_stream ) << ": " << diagnostic.message;
+    if( diagnostic.occurrences > 1 ) ( *_stream ) << " (" << diagnostic.occurrences << " occurrences)";
+    ( *_stream ) << std::endl;
+}
@@ -0,0 +1,137 @@
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+
+#include "cllazyfile/lazyInstMgr.h"
+
+namespace {
+void require( bool condition, const char * message ) {
+    if( !condition ) {
+        std::cerr << "lazy_index_test: " << message << std::endl;
+        std::exit( EXIT_FAILURE );
+    }
+}
+
+void emptyRegistryInit( Registry & ) {
+}
+}
+
+int main( int argc, char ** argv ) {
+    require( argc == 3, "expected ordinary and scoped fixture paths" );
+
+    lazyInstMgr manager;
+    uint64_t progressCalls = 0;
+    uint64_t diagnosticCalls = 0;
+    LazyDiagnostic missingReference;
+    manager.setProgressCallback( [&progressCalls]( const LazyScanProgress & progress ) {
+        require( progress.fileSize >= progress.offset, "progress offset exceeds file size" );
+        ++progressCalls;
+    } );
+    manager.setDiagnosticCallback( [&diagnosticCalls, &missingReference]( const LazyDiagnostic & diagnostic ) {
+        ++diagnosticCalls;
+        if( diagnostic.entity == 5 ) missingReference = diagnostic;
+    } );
+    manager.openFile( argv[1] );
+
+    LazyCacheStatistics stats = manager.cacheStatistics();
+    require( stats.instancesScanned == 5, "wrong scan count" );
+    require( stats.dataSections == 2, "second DATA section was not indexed" );
+    require( progressCalls > 0, "progress callback was not called" );
+    require( manager.instancesByType( "a" ).size() == 1, "case-insensitive type index failed" );
+    require( manager.allInstances().size() == manager.totalInstanceCount(), "all-instance index count failed" );
+    require( manager.instancesByType( "C" ).size() == 1, "first complex component not indexed" );
+    require( manager.instancesByType( "D" ).size() == 1, "second complex component not indexed" );
+    require( manager.instancesByType( "" ).size() == 1, "complex instance index failed" );
+    require( manager.componentTypes( 3 ).size() == 2 &&
+        manager.componentTypes( 3 )[0] == "C" &&
+        manager.componentTypes( 3 )[1] == "D",
+        "complex component source order was not preserved" );
+    require( manager.componentTypes( 1 ).empty() &&
+        manager.componentTypes( 99 ).empty(),
+        "ordinary or missing instance has complex components" );
+    require( diagnosticCalls == 1, "structured diagnostic callback was not bounded" );
+    require( missingReference.severity == LAZY_DIAGNOSTIC_ERROR && missingReference.offset > 0,
+        "missing-reference diagnostic lacks structured context" );
+    require( missingReference.message == "reference to missing instance #99", "wrong missing-reference diagnostic" );
+    require( manager.forwardReferences( 1 ).size() == 1 && manager.forwardReferences( 1 )[0] == 2,
+        "forward reference index failed" );
+    require( manager.reverseReferences( 1 ).size() == 1 && manager.reverseReferences( 1 )[0] == 3,
+        "reverse reference index failed" );
+    const std::string firstSource = manager.sourceRecord( 1 );
+    const std::string secondSource = manager.sourceRecord( 2 );
+    require( firstSource.find( "#1=A(" ) != std::string::npos &&
+        !firstSource.empty() && firstSource[firstSource.size() - 1] == ';',
+        "first exact source record failed" );
+    require( secondSource.find( "#2=B();" ) != std::string::npos &&
+        !secondSource.empty() && secondSource[secondSource.size() - 1] == ';',
+        "second exact source record or stream restoration failed" );
+    require( manager.sourceRecord( 99 ).empty(),
+        "missing source record was not empty" );
+
+    Registry emptyRegistry( emptyRegistryInit );
+    manager.setRegistry( &emptyRegistry );
+    std::ostringstream schemaWarnings;
+    std::streambuf * originalCerr = std::cerr.rdbuf( schemaWarnings.rdbuf() );
+    LazyInstanceBatch missingBatch = manager.loadBatch( 5 );
+    LazyInstanceBatch secondBatch = manager.loadBatch( 1 );
+    std::cerr.rdbuf( originalCerr );
+    require( missingBatch.instances().size() == 1 &&
+        missingBatch.instances()[0] == 5,
+        "missing reference leaked into materialization closure" );
+    const std::string warningText =
+        "Warning - multiple schema names found. Only searching with first one.";
+    const size_t firstWarning = schemaWarnings.str().find( warningText );
+    require( firstWarning != std::string::npos &&
+        schemaWarnings.str().find( warningText, firstWarning + 1 ) ==
+            std::string::npos,
+        "multiple FILE_SCHEMA warning was not bounded per file" );
+    require( schemaWarnings.str().find( "Error loading instance" ) ==
+            std::string::npos,
+        "structured materialization diagnostic was also written to stderr" );
+    secondBatch.release();
+    missingBatch.release();
+
+    lazyInstMgr cancelled;
+    uint64_t cancellationCalls = 0;
+    cancelled.setCancellationCallback( [&cancellationCalls]() {
+        return ++cancellationCalls >= 2;
+    } );
+    cancelled.openFile( argv[1] );
+    stats = cancelled.cacheStatistics();
+    require( stats.cancelled, "cancellation was not recorded" );
+    require( stats.instancesScanned == 2, "scan did not stop at cancellation boundary" );
+
+    lazyInstMgr scoped;
+    require( scoped.openFile( argv[2] ), "scoped fixture did not open" );
+    stats = scoped.cacheStatistics();
+    require( stats.instancesScanned == 5, "wrong scoped scan count" );
+    require( scoped.instancesByType( "A" ).size() == 3,
+        "scoped simple instances were not indexed" );
+    require( scoped.instancesByType( "B" ).size() == 1,
+        "nested scoped instance was not indexed" );
+    require( scoped.instancesByType( "C" ).size() == 1 &&
+        scoped.instancesByType( "D" ).size() == 1 &&
+        scoped.instancesByType( "" ).size() == 1,
+        "scoped complex owner was not indexed" );
+    require( scoped.forwardReferences( 11 ).size() == 1 &&
+        scoped.forwardReferences( 11 )[0] == 12,
+        "nested scoped reference was not indexed" );
+    require( scoped.forwardReferences( 20 ).size() == 1 &&
+        scoped.forwardReferences( 20 )[0] == 21,
+        "complex scope-owner reference was not indexed" );
+    require( scoped.componentTypes( 20 ).size() == 2 &&
+        scoped.componentTypes( 20 )[0] == "C" &&
+        scoped.componentTypes( 20 )[1] == "D",
+        "scoped complex component order was not preserved" );
+    const std::string nestedOwner = scoped.sourceRecord( 11 );
+    const std::string complexOwner = scoped.sourceRecord( 20 );
+    require( nestedOwner.find( "#11=&SCOPE" ) != std::string::npos &&
+        nestedOwner.find( "ENDSCOPE /#12/ A(" ) != std::string::npos &&
+        !nestedOwner.empty() && nestedOwner[nestedOwner.size() - 1] == ';',
+        "nested scope source record was not preserved" );
+    require( complexOwner.find( "#20=&SCOPE" ) != std::string::npos &&
+        complexOwner.find( "ENDSCOPE (C()D(" ) != std::string::npos &&
+        !complexOwner.empty() && complexOwner[complexOwner.size() - 1] == ';',
+        "complex scope source record was not preserved" );
+    return EXIT_SUCCESS;
+}
@@ -171,6 +171,34 @@ int main( int argc, char ** argv ) {
 #ifndef NO_REGISTRY
    if( instWithRef ) {
        std::cout << "Number of data section instances fully loaded: " << mgr->loadedInstanceCount() << std::endl;
+        {
+            LazyInstanceBatch first = mgr->loadBatch( instWithRef );
+            LazyInstanceBatch second = mgr->loadBatch( instWithRef );
+            size_t sharedSize = second.instances().size();
+            first.release();
+            if( mgr->loadedInstanceCount() != sharedSize || !second.get( instWithRef ) ) {
+                std::cerr << "Releasing one batch evicted instances pinned by another batch" << std::endl;
+                return EXIT_FAILURE;
+            }
+        }
+        if( mgr->loadedInstanceCount() != 0 ) {
+            std::cerr << "Shared dependency batches did not release their cache" << std::endl;
+            return EXIT_FAILURE;
+        }
+        for( int cycle = 0; cycle < 3; ++cycle ) {
+            {
+                LazyInstanceBatch batch = mgr->loadBatch( instWithRef );
+                if( !batch.valid() || !batch.get( instWithRef ) ) {
+                    std::cerr << "Unable to materialize dependency batch for #" << instWithRef << std::endl;
+                    return EXIT_FAILURE;
+                }
+                std::cout << "Batch-pinned instances: " << batch.instances().size() << std::endl;
+            }
+            if( mgr->loadedInstanceCount() != 0 ) {
+                std::cerr << "Dependency batch did not return the cache to its initial size" << std::endl;
+                return EXIT_FAILURE;
+            }
+        }
        std::cout << "Loading #" << instWithRef;
        SDAI_Application_instance * inst = mgr->loadInstance( instWithRef );
        std::cout << " which is of type " << inst->EntityName() << std::endl;
@@ -193,4 +221,3 @@ int main( int argc, char ** argv ) {
    delete mgr;
    //stats will print from its destructor
 }
-
@@ -34,7 +34,11 @@ const namedLazyInstance p21HeaderSectionReader::nextInstance() {
    static instanceID nextFreeInstance = 4; // 1-3 are reserved per 10303-21

    i.refs = 0;
-    i.loc.begin = _file.tellg();
+    i.componentTypes = 0;
+    i.loc.end = 0;
+    std::streampos start = _file.tellg();
+    i.loc.begin = start == std::streampos( -1 ) ? 0 :
+        static_cast<lazyFileOffset>( static_cast<std::streamoff>( start ) );
    i.loc.section = _sectionID;
    skipWS();
    if( i.loc.begin <= 0 ) {
@@ -55,12 +59,14 @@ const namedLazyInstance p21HeaderSectionReader::nextInstance() {
        assert( strlen( i.name ) > 0 );

        std::streampos end = seekInstanceEnd( 0 ); //no references in file header
+        if( end != std::streampos( -1 ) ) {
+            i.loc.end = static_cast<lazyFileOffset>( static_cast<std::streamoff>( end ) );
+        }
        if( ( (signed long int)end == -1 ) || ( end >= _sectionEnd ) ) {
            //invalid instance, so clear everything
-            i.loc.begin = -1;
+            i.loc.begin = 0;
            i.name = 0;
        }
    }
    return i;
 }
-
@@ -1,11 +1,16 @@
+#ifndef SC_CORE_EXPORT
 #define SC_CORE_EXPORT
+#endif
+#ifndef SC_DAI_EXPORT
 #define SC_DAI_EXPORT
+#endif

 #include <algorithm>
 #include <set>
 #include <string>
 #include <assert.h>
 #include <limits.h>
+#include <limits>

 #ifdef _WIN32
 #  define strtoull _strtoui64
@@ -35,6 +40,112 @@ sectionReader::~sectionReader() {
     delete _error;
 }

+bool sectionReader::skipComment() {
+    int previous = 0;
+    int current;
+    while( current = _file.get(), _file.good() ) {
+        if( previous == '*' && current == '/' ) {
+            return true;
+        }
+        previous = current;
+    }
+    return false;
+}
+
+
+bool sectionReader::skipTokenSeparators() {
+    while( _file.good() ) {
+        skipWS();
+        if( _file.peek() != '/' ) return _file.good();
+        const std::streampos slash = _file.tellg();
+        _file.get();
+        if( _file.peek() != '*' ) {
+            _file.seekg( slash );
+            return _file.good();
+        }
+        _file.get(); // consume the opening star
+        if( !skipComment() ) return false;
+    }
+    return false;
+}
+
+
+bool sectionReader::skipScopeExportList() {
+    if( !skipTokenSeparators() ) return false;
+    if( _file.peek() != '/' ) return true;
+    _file.get();
+
+    bool haveExport = false;
+    while( _file.good() ) {
+        if( !skipTokenSeparators() || _file.get() != '#' ) return false;
+        bool haveDigit = false;
+        bool haveNonzeroDigit = false;
+        while( _file.good() && isdigit( _file.peek() ) ) {
+            const int digit = _file.get();
+            haveDigit = true;
+            if( digit != '0' ) haveNonzeroDigit = true;
+        }
+        if( !haveDigit || !haveNonzeroDigit || !skipTokenSeparators() ) return false;
+        haveExport = true;
+        const int delimiter = _file.get();
+        if( delimiter == '/' ) return haveExport;
+        if( delimiter != ',' ) return false;
+    }
+    return false;
+}
+
+
+bool sectionReader::skipScope() {
+    if( !skipTokenSeparators() || _file.get() != '&' ) return false;
+    skipWS();
+    static const char scopeKeyword[] = "SCOPE";
+    for( size_t i = 0; scopeKeyword[i]; ++i ) {
+        if( _file.get() != scopeKeyword[i] ) return false;
+    }
+
+    int depth = 1;
+    while( depth > 0 && _file.good() ) {
+        const int current = _file.get();
+        if( current == '\'' ) {
+            _file.seekg( _file.tellg() - std::streampos( 1 ) );
+            GetLiteralStr( _file, _lazyFile->getInstMgr()->getErrorDesc() );
+            continue;
+        }
+        if( current == '/' && _file.peek() == '*' ) {
+            _file.get();
+            if( !skipComment() ) return false;
+            continue;
+        }
+        if( current == '&' ) {
+            const std::streampos afterAmpersand = _file.tellg();
+            skipWS();
+            std::string keyword;
+            while( _file.good() && ( isupper( _file.peek() ) ||
+                    isdigit( _file.peek() ) || _file.peek() == '_' ||
+                    _file.peek() == '-' ) ) {
+                keyword.push_back( static_cast<char>( _file.get() ) );
+            }
+            if( keyword == "SCOPE" ) {
+                ++depth;
+            } else {
+                _file.seekg( afterAmpersand );
+            }
+            continue;
+        }
+        if( isupper( current ) ) {
+            std::string keyword( 1, static_cast<char>( current ) );
+            while( _file.good() && ( isupper( _file.peek() ) ||
+                    isdigit( _file.peek() ) || _file.peek() == '_' ||
+                    _file.peek() == '-' ) ) {
+                keyword.push_back( static_cast<char>( _file.get() ) );
+            }
+            if( keyword == "ENDSCOPE" ) --depth;
+        }
+    }
+    return depth == 0 && skipScopeExportList();
+}
+
+
 std::streampos sectionReader::findNormalString( const std::string & str, bool semicolon ) {
    std::streampos found = -1, startPos = _file.tellg(), nextTry = startPos;
    int i = 0, l = str.length();
@@ -59,8 +170,11 @@ std::streampos sectionReader::findNormalString( const std::string & str, bool se
            GetLiteralStr( _file, _lazyFile->getInstMgr()->getErrorDesc() );
        }
        if( ( c == '/' ) && ( _file.peek() == '*' ) ) {
-            //push past comment
-            findNormalString( "*/" );
+            _file.get(); // consume the opening star
+            if( !skipComment() ) {
+                return -1;
+            }
+            continue;
        }
        if( str[i] == c ) {
            i++;
@@ -88,6 +202,32 @@ std::streampos sectionReader::findNormalString( const std::string & str, bool se
 }


+std::string sectionReader::sourceRecord( lazyFileOffset begin, uint64_t length ) {
+    if( begin == 0 || length == 0 ||
+            length > static_cast<uint64_t>( std::numeric_limits<std::streamsize>::max() ) ||
+            length > static_cast<uint64_t>( std::numeric_limits<size_t>::max() ) ) {
+        return std::string();
+    }
+
+    const std::streampos saved = _file.tellg();
+    _file.clear();
+    _file.seekg( static_cast<std::streamoff>( begin ) );
+    if( !_file.good() ) {
+        _file.clear();
+        if( saved != std::streampos( -1 ) ) _file.seekg( saved );
+        return std::string();
+    }
+
+    std::string source( static_cast<size_t>( length ), '\0' );
+    _file.read( &source[0], static_cast<std::streamsize>( length ) );
+    const bool complete = static_cast<uint64_t>( _file.gcount() ) == length;
+
+    _file.clear();
+    if( saved != std::streampos( -1 ) ) _file.seekg( saved );
+    return complete ? source : std::string();
+}
+
+
 //NOTE different behavior than const char * GetKeyword( istream & in, const char * delims, ErrorDescriptor & err ) in read_func.cc
 // returns pointer to the contents of a static std::string
 const char * sectionReader::getDelimitedKeyword( const char * delimiters ) {
@@ -102,7 +242,10 @@ const char * sectionReader::getDelimitedKeyword( const char * delimiters ) {
            str.append( 1, c );
        } else if( ( c == '/' ) && ( _file.peek() == '*' ) && ( str.length() == 0 ) ) {
            //push past comment
-            findNormalString( "*/" );
+            _file.get(); // consume the opening star
+            if( !skipComment() ) {
+                break;
+            }
            skipWS();
            continue;
        } else {
@@ -111,7 +254,7 @@ const char * sectionReader::getDelimitedKeyword( const char * delimiters ) {
        }
    }
    c = _file.peek();
-    if( !strchr( delimiters, c ) ) {
+    if( !strchr( delimiters, c ) && !isspace( static_cast<unsigned char>( c ) ) ) {
        std::cerr << SC_CURRENT_FUNCTION << ": missing delimiter. Found " << c << ", expected one of " << delimiters << " at end of keyword " << str << ". File offset: " << _file.tellg() << std::endl;
        abort();
    }
@@ -121,17 +264,22 @@ const char * sectionReader::getDelimitedKeyword( const char * delimiters ) {
 /// search forward in the file for the end of the instance. Start position should
 /// be the opening parenthesis; otherwise, it is likely to fail.
 ///NOTE *must* check return value!
-std::streampos sectionReader::seekInstanceEnd( instanceRefs ** refs ) {
+std::streampos sectionReader::seekInstanceEnd( instanceRefs ** refs, std::vector<std::string> * componentTypes ) {
    int c;
    int parenDepth = 0;
+    bool expectComplexType = false;
    while( c = _file.get(), _file.good() ) {
        switch( c ) {
            case '(':
                parenDepth++;
+                if( componentTypes && parenDepth == 1 ) expectComplexType = true;
                break;
            case '/':
                if( _file.peek() == '*' ) {
-                    findNormalString( "*/" );
+                    _file.get(); // consume the opening star
+                    if( !skipComment() ) {
+                        return -1;
+                    }
                } else {
                    return -1;
                }
@@ -158,7 +306,8 @@ std::streampos sectionReader::seekInstanceEnd( instanceRefs ** refs ) {
                }
                break;
            case ')':
-                if( --parenDepth == 0 ) {
+                if( --parenDepth == 1 && componentTypes ) expectComplexType = true;
+                if( parenDepth == 0 ) {
                    skipWS();
                    if( _file.get() == ';' ) {
                        return _file.tellg();
@@ -166,7 +315,23 @@ std::streampos sectionReader::seekInstanceEnd( instanceRefs ** refs ) {
                        _file.seekg( _file.tellg() - std::streampos(1) );
                    }
                }
+                break;
            default:
+                if( componentTypes && parenDepth == 1 && expectComplexType &&
+                        ( isupper( c ) || c == '!' ) ) {
+                    std::string type( 1, static_cast<char>( c ) );
+                    while( _file.good() ) {
+                        int next = _file.get();
+                        if( next == '-' || next == '_' || isupper( next ) || isdigit( next ) ) {
+                            type.push_back( static_cast<char>( next ) );
+                        } else {
+                            _file.putback( static_cast<char>( next ) );
+                            break;
+                        }
+                    }
+                    componentTypes->push_back( type );
+                    expectComplexType = false;
+                }
                break;
        }
    }
@@ -192,7 +357,10 @@ instanceID sectionReader::readInstanceNumber() {
    skipWS();
    c = _file.get();
    if( ( c == '/' ) && ( _file.peek() == '*' ) ) {
-        findNormalString( "*/" );
+        _file.get(); // consume the opening star
+        if( !skipComment() ) {
+            return 0;
+        }
    } else {
        _file.seekg( _file.tellg() - std::streampos(1) );
    }
@@ -257,10 +425,11 @@ instanceID sectionReader::readInstanceNumber() {
 /** load an instance and return a pointer to it.
 * side effect: recursively loads any instances the specified instance depends upon
 */
-SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg, long int begin, instanceID instance,
+SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg, lazyFileOffset begin, instanceID instance,
        const std::string & typeName, const std::string & schName, bool header ) {
    int c;
    const char * tName = 0, * sName = 0; //these are necessary since typeName and schName are const
+    std::string normalizedSchema;
    std::string comment;
    Severity sev = SEVERITY_NULL;
    SDAI_Application_instance * inst = 0;
@@ -273,17 +442,20 @@ SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg
        if( fs ) {
            StringNode * sn = ( StringNode * ) fs->schema_identifiers_()->GetHead();
            if( sn ) {
-                sName = sn->value.c_str();
-                if( sn->NextNode() ) {
+                normalizedSchema = sn->value.c_str();
+                size_t qualifier = normalizedSchema.find_first_of( " {" );
+                if( qualifier != std::string::npos ) normalizedSchema.erase( qualifier );
+                sName = normalizedSchema.c_str();
+                if( sn->NextNode() && _lazyFile->claimSchemaWarning() ) {
                    std::cerr << "Warning - multiple schema names found. Only searching with first one." << std::endl;
                }
            }
-        } else {
+        } else if( _lazyFile->claimSchemaWarning() ) {
            std::cerr << "Warning - no schema names found; the file is probably invalid. Looking for typeName in any loaded schema." << std::endl;
        }
    }

-    _file.seekg( begin );
+    _file.seekg( static_cast<std::streamoff>( begin ) );
    skipWS();
    ReadTokenSeparator( _file, &comment );
    if( !header ) {
@@ -292,11 +464,11 @@ SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg
    skipWS();
    ReadTokenSeparator( _file, &comment );
    c = _file.peek();
+    if( c == '&' ) {
+        if( !skipScope() || !skipTokenSeparators() ) return 0;
+        c = _file.peek();
+    }
    switch( c ) {
-        case '&':
-            std::cerr << "Can't handle scope instances. Skipping #" << instance << ", offset " << _file.tellg() << std::endl;
-            // sev = CreateScopeInstances( in, &scopelist );
-            break;
        case '(':
            inst = CreateSubSuperInstance( reg, instance, sev );
            break;
@@ -307,6 +479,11 @@ SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg
            if( ( !header ) && ( typeName.size() == 0 ) ) {
                tName = getDelimitedKeyword( ";( /\\" );
            }
+            std::string materializationType;
+            if( !header && tName ) {
+                materializationType = _lazyFile->getInstMgr()->materializationType( tName );
+                tName = materializationType.c_str();
+            }
            inst = reg->ObjCreate( tName, sName );
            break;
    }
@@ -315,7 +492,18 @@ SDAI_Application_instance * sectionReader::getRealInstance( const Registry * reg
            inst->AddP21Comment( comment );
        }
        assert( inst->eDesc );
-        _file.seekg( begin );
+        _file.seekg( static_cast<std::streamoff>( begin ) );
+        if( !header ) {
+            if( findNormalString( "=" ) == std::streampos( -1 ) ||
+                    !skipTokenSeparators() ) {
+                delete inst;
+                return 0;
+            }
+            if( _file.peek() == '&' && ( !skipScope() || !skipTokenSeparators() ) ) {
+                delete inst;
+                return 0;
+            }
+        }
        findNormalString( "(" );
        _file.seekg( _file.tellg() - std::streampos(1) );
        sev = inst->STEPread( instance, 0, _lazyFile->getInstMgr()->getAdapter(), _file, sName, true, false );
@@ -356,7 +544,6 @@ STEPcomplex * sectionReader::CreateSubSuperInstance( const Registry * reg, insta
    //TODO still need the schema name
    STEPcomplex * sc = new STEPcomplex( ( const_cast<Registry *>( reg ) ), names, ( int ) fileid /*, schnm*/ );
    delete[] names;
-    //TODO also delete contents of typeNames!
+    for( int i = 0; i < s; i++ ) delete typeNames[i];
    return sc;
 }
-
@@ -0,0 +1,25 @@
+SCHEMA lazy_test_schema;
+
+ENTITY b;
+END_ENTITY;
+
+ENTITY a;
+    opt : OPTIONAL STRING;
+    label : STRING;
+    ref : b;
+END_ENTITY;
+
+ENTITY c;
+END_ENTITY;
+
+ENTITY d
+    SUBTYPE OF (c);
+    ref : a;
+END_ENTITY;
+
+ENTITY e;
+    ref : d;
+    opt : OPTIONAL STRING;
+END_ENTITY;
+
+END_SCHEMA;
@@ -0,0 +1,17 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('lazy index test'),'2;1');
+FILE_NAME('lazy_index.stp','2026-07-17T00:00:00',('STEPcode'),('STEPcode'),'','','');
+FILE_SCHEMA(('LAZY_TEST_SCHEMA { 1 0 10303 999 }','UNUSED_TEST_SCHEMA'));
+ENDSEC;
+DATA('second',('LAZY_TEST_SCHEMA'));
+#1=A($,'escaped quote '' and unicode \X2\03A9\X0\',#2);
+#2=B();
+ENDSEC;
+/* A second data section must not be consumed by lookahead. */
+DATA;
+#3=(C()D(#1));
+#4=E(#3,$);
+#5=E(#99,$);
+ENDSEC;
+END-ISO-10303-21;
@@ -0,0 +1,17 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('lazy scope test'),'1;1');
+FILE_NAME('lazy_scope.stp','2026-07-31T00:00:00',('STEPcode'),('STEPcode'),'','','');
+FILE_SCHEMA(('LAZY_TEST_SCHEMA { 1 0 10303 999 }'));
+ENDSEC;
+DATA;
+#10=&SCOPE
+#11=&SCOPE
+#12=B();
+ENDSCOPE /#12/ A($,'nested owner',#12);
+ENDSCOPE /#11/ A($,'outer owner',#12);
+#20=&SCOPE
+#21=A($,'complex child',#12);
+ENDSCOPE (C()D(#21));
+ENDSEC;
+END-ISO-10303-21;
@@ -34,6 +34,8 @@ set(CORE_SRCS
  read_func.cc
  Registry.cc
  schRename.cc
+  schemaInit.cc
+  schemaModule.cc
  sdai.cc
  sdaiApplication_instance.cc
  sdaiSelect.cc
@@ -66,9 +68,8 @@ include_directories(
  ${CMAKE_SOURCE_DIR}/include/stepcode
  )

-set(_libdeps steputils stepdai)
-
 if(BUILD_SHARED_LIBS)
+  set(_libdeps steputils stepdai)
  SC_ADDLIB(stepcore SHARED SOURCES ${CORE_SRCS} LINK_LIBRARIES ${_libdeps})
  if(WIN32)
    target_compile_definitions(stepcore PRIVATE SC_CORE_DLL_EXPORTS)
@@ -76,7 +77,8 @@ if(BUILD_SHARED_LIBS)
 endif()

 if(BUILD_STATIC_LIBS)
-  SC_ADDLIB(stepcore-static STATIC SOURCES ${CORE_SRCS} LINK_LIBRARIES $<JOIN:${_libdeps},-static>-static)
+  set(_libdeps steputils-static stepdai-static)
+  SC_ADDLIB(stepcore-static STATIC SOURCES ${CORE_SRCS} LINK_LIBRARIES ${_libdeps})
 endif()

 if(SC_ENABLE_TESTING)
@@ -89,4 +91,3 @@ endif(SC_ENABLE_TESTING)
 # indent-tabs-mode: t
 # End:
 # ex: shiftwidth=2 tabstop=8
-
@@ -248,8 +248,10 @@ void Registry::RemoveClones( const EntityDescriptor & e ) {
 SDAI_Application_instance * Registry::ObjCreate( const char * nm, const char * schnm, int check_case ) const {
    const EntityDescriptor  * entd = FindEntity( nm, schnm, check_case );
    if( entd ) {
-        SDAI_Application_instance * se =
-            ( ( EntityDescriptor * )entd ) -> NewSTEPentity();
+        SDAI_Application_instance * se = entd->CreateEntity();
+        if( !se ) {
+            return ENTITY_NULL;
+        }

        // See comment in previous function.
        if( entd->AbstractEntity().asInt() == 1 ) {
@@ -91,7 +91,7 @@ Severity EntityAggregate::ReadValue( istream & in, ErrorDescriptor * err,
        CheckRemainingInput( in, &errdesc, buf, ",)" );

        if( errdesc.severity() < SEVERITY_INCOMPLETE ) {
-            sprintf( errmsg, "  index:  %d\n", value_cnt );
+            snprintf( errmsg, sizeof(errmsg), "  index:  %d\n", value_cnt );
            errdesc.PrependToDetailMsg( errmsg );
            err->AppendFromErrorArg( &errdesc );
        }
@@ -221,7 +221,7 @@ const char * EntityNode::asStr( std::string & s ) {
        return "";
    } else { // otherwise return entity id
        char tmp [64];
-        sprintf( tmp, "#%d", node->STEPfile_id );
+        snprintf( tmp, sizeof(tmp), "#%d", node->STEPfile_id );
        s = tmp;
    }
    return const_cast<char *>( s.c_str() );
@@ -96,7 +96,7 @@ const char * IntNode::asStr( std::string & s ) {
 const char * IntNode::STEPwrite( std::string & s, const char * ) {
    char tmp[BUFSIZ+1];
    if( value != S_INT_NULL ) {
-        sprintf( tmp, "%ld", value );
+        snprintf( tmp, sizeof(tmp), "%ld", value );
        s = tmp;
    } else {
        s.clear();
@@ -1,12 +1,13 @@
 #include "clstepcore/STEPaggrSelect.h"
-#include "clstepcore/typeDescriptor.h"
+#include "clstepcore/selectTypeDescriptor.h"
 #include <sstream>

 /** \file STEPaggrSelect.cc
 * implement classes SelectAggregate, SelectNode
 */

-SelectAggregate::SelectAggregate() {
+SelectAggregate::SelectAggregate( const SelectTypeDescriptor * select_type )
+    : _select_type( select_type ) {
 }

 SelectAggregate::~SelectAggregate() {
@@ -87,7 +88,7 @@ Severity SelectAggregate::ReadValue( istream & in, ErrorDescriptor * err,
        CheckRemainingInput( in, &errdesc, buf, ",)" );

        if( errdesc.severity() < SEVERITY_INCOMPLETE ) {
-            sprintf( errmsg, "  index:  %d\n", value_cnt );
+            snprintf( errmsg, sizeof(errmsg), "  index:  %d\n", value_cnt );
            errdesc.PrependToDetailMsg( errmsg );
            err->AppendFromErrorArg( &errdesc );
        }
@@ -119,9 +120,10 @@ Severity SelectAggregate::ReadValue( istream & in, ErrorDescriptor * err,


 STEPaggregate & SelectAggregate::ShallowCopy( const STEPaggregate & a ) {
+    Empty();
    const SelectNode * tmp = ( const SelectNode * ) a.GetHead();
    while( tmp ) {
-        AddNode( new SelectNode( tmp -> node ) );
+        AddNode( new SelectNode( tmp->node ? tmp->node->Clone() : 0 ) );

        tmp = ( const SelectNode * ) tmp -> NextNode();
    }
@@ -136,14 +138,18 @@ STEPaggregate & SelectAggregate::ShallowCopy( const STEPaggregate & a ) {


 SingleLinkNode * SelectAggregate::NewNode() {
-    return new SelectNode();
+    SDAI_Select * select = _select_type ? _select_type->CreateSelect() : 0;
+    if( !select && _select_type ) {
+        select = new SDAI_Select( _select_type );
+    }
+    return new SelectNode( select );
 }


 SelectNode::SelectNode( SDAI_Select  * s ) :  node( s ) {
 }

-SelectNode::SelectNode() {
+SelectNode::SelectNode() : node( 0 ) {
 }

 SelectNode::~SelectNode() {
@@ -221,4 +227,3 @@ void SelectNode::STEPwrite( ostream & out ) {
    std::string s;
    out << asStr( s );
 }
-
@@ -174,7 +174,7 @@ Severity STEPaggregate::ReadValue( istream & in, ErrorDescriptor * err,
        CheckRemainingInput( in, &errdesc, buf, ",)" );

        if( errdesc.severity() < SEVERITY_INCOMPLETE ) {
-            sprintf( errmsg, "  index:  %d\n", value_cnt );
+            snprintf( errmsg, sizeof(errmsg), "  index:  %d\n", value_cnt );
            errdesc.PrependToDetailMsg( errmsg );
            err->AppendFromErrorArg( &errdesc );
        }
@@ -392,18 +392,19 @@ const char * STEPattribute::asStr( std::string & str, const char * currSch ) con

    str.clear();

+    // The attribute has been redefined by the attribute pointed
+    // to by _redefAttr so write the narrowed value in the inherited
+    // physical-file slot.  STEPread and StrToVal use this same precedence.
+    if( _redefAttr )  {
+        return _redefAttr->asStr( str, currSch );
+    }
+
    // The attribute has been derived by a subtype's attribute
    if( IsDerived() )  {
        str = "*";
        return const_cast<char *>( str.c_str() );
    }

-    // The attribute has been redefined by the attribute pointed
-    // to by _redefAttr so write the redefined value.
-    if( _redefAttr )  {
-        return _redefAttr->asStr( str, currSch );
-    }
-
    if( is_null() )  {
        str = "";
        return const_cast<char *>( str.c_str() );
@@ -485,18 +486,19 @@ std::string STEPattribute::asStr( const char * currSch ) const {
    ostringstream ss;
    std::string str;

+    // The attribute has been redefined by the attribute pointed
+    // to by _redefAttr so write the narrowed value in the inherited
+    // physical-file slot.  STEPread and StrToVal use this same precedence.
+    if( _redefAttr )  {
+        return _redefAttr->asStr( currSch );
+    }
+
    // The attribute has been derived by a subtype's attribute
    if( IsDerived() )  {
        str = "*";
        return str;
    }

-    // The attribute has been redefined by the attribute pointed
-    // to by _redefAttr so write the redefined value.
-    if( _redefAttr )  {
-        return _redefAttr->asStr( currSch );
-    }
-
    if( is_null() )  {
        return str;
    }
@@ -587,17 +589,18 @@ void STEPattribute::STEPwriteError( ostream & out, unsigned int line, const char
 *
 */
 void STEPattribute::STEPwrite( ostream & out, const char * currSch ) {
+    // The attribute has been redefined by the attribute pointed
+    // to by _redefAttr so write the narrowed value in the inherited
+    // physical-file slot.  STEPread and StrToVal use this same precedence.
+    if( _redefAttr )  {
+        _redefAttr->STEPwrite( out, currSch );
+        return;
+    }
    // The attribute has been derived by a subtype's attribute
    if( IsDerived() ) {
        out << "*";
        return;
    }
-    // The attribute has been redefined by the attribute pointed
-    // to by _redefAttr so write the redefined value.
-    if( _redefAttr )  {
-        _redefAttr->STEPwrite( out );
-        return;
-    }

    if( is_null() ) {
        out << "$";
@@ -686,6 +689,10 @@ void STEPattribute::STEPwrite( ostream & out, const char * currSch ) {


 void STEPattribute::ShallowCopy( const STEPattribute * sa ) {
+    if( sa == this ) {
+        return;
+    }
+    DeleteOwnedPtr();
    _mustDeletePtr = false;
    aDesc = sa->aDesc;
    refCount = 0;
@@ -918,6 +925,9 @@ bool STEPattribute::is_null()  const {
 // these get the attr value

 SDAI_Integer * STEPattribute::Integer(){
+    if( _redefAttr ) {
+        return _redefAttr->Integer();
+    }
    if( NonRefType() == INTEGER_TYPE ) {
        return ptr.i;
    }
@@ -925,6 +935,9 @@ SDAI_Integer * STEPattribute::Integer(){
 }

 SDAI_Real * STEPattribute::Number() {
+    if( _redefAttr ) {
+        return _redefAttr->Number();
+    }
    if( NonRefType() == NUMBER_TYPE ) {
        return ptr.r;
    }
@@ -932,6 +945,9 @@ SDAI_Real * STEPattribute::Number() {
 }

 SDAI_Real * STEPattribute::Real() {
+    if( _redefAttr ) {
+        return _redefAttr->Real();
+    }
    if( NonRefType() == REAL_TYPE ) {
        return ptr.r;
    }
@@ -939,6 +955,9 @@ SDAI_Real * STEPattribute::Real() {
 }

 SDAI_Application_instance * STEPattribute::Entity() {
+    if( _redefAttr ) {
+        return _redefAttr->Entity();
+    }
    if( NonRefType() == ENTITY_TYPE ) {
        return *( ptr.c );
    }
@@ -946,6 +965,9 @@ SDAI_Application_instance * STEPattribute::Entity() {
 }

 SDAI_String * STEPattribute::String() {
+    if( _redefAttr ) {
+        return _redefAttr->String();
+    }
    if( NonRefType() == STRING_TYPE ) {
        return ptr.S;
    }
@@ -953,6 +975,9 @@ SDAI_String * STEPattribute::String() {
 }

 SDAI_Binary * STEPattribute::Binary() {
+    if( _redefAttr ) {
+        return _redefAttr->Binary();
+    }
    if( NonRefType() == BINARY_TYPE ) {
        return ptr.b;
    }
@@ -960,6 +985,9 @@ SDAI_Binary * STEPattribute::Binary() {
 }

 STEPaggregate * STEPattribute::Aggregate() {
+    if( _redefAttr ) {
+        return _redefAttr->Aggregate();
+    }
    if( ( NonRefType() == AGGREGATE_TYPE ) || ( NonRefType() == ARRAY_TYPE ) || ( NonRefType() == BAG_TYPE )
        || ( NonRefType() == SET_TYPE ) || ( NonRefType() == LIST_TYPE ) ) {
        return ptr.a;
@@ -968,6 +996,9 @@ STEPaggregate * STEPattribute::Aggregate() {
 }

 SDAI_BOOLEAN * STEPattribute::Boolean() {
+    if( _redefAttr ) {
+        return _redefAttr->Boolean();
+    }
    if( NonRefType() == BOOLEAN_TYPE ) {
        return ( SDAI_BOOLEAN * ) ptr.e;
    }
@@ -975,6 +1006,9 @@ SDAI_BOOLEAN * STEPattribute::Boolean() {
 }

 SDAI_LOGICAL * STEPattribute::Logical() {
+    if( _redefAttr ) {
+        return _redefAttr->Logical();
+    }
    if( NonRefType() == LOGICAL_TYPE ) {
        return ( SDAI_LOGICAL * ) ptr.e;
    }
@@ -982,6 +1016,9 @@ SDAI_LOGICAL * STEPattribute::Logical() {
 }

 SDAI_Enum * STEPattribute::Enum() {
+    if( _redefAttr ) {
+        return _redefAttr->Enum();
+    }
    if( NonRefType() == ENUM_TYPE ) {
        return ptr.e;
    }
@@ -989,6 +1026,9 @@ SDAI_Enum * STEPattribute::Enum() {
 }

 SDAI_Select * STEPattribute::Select() {
+    if( _redefAttr ) {
+        return _redefAttr->Select();
+    }
    if( NonRefType() == SELECT_TYPE ) {
        return ptr.sh;
    }
@@ -996,6 +1036,9 @@ SDAI_Select * STEPattribute::Select() {
 }

 SCLundefined * STEPattribute::Undefined() {
+    if( _redefAttr ) {
+        return _redefAttr->Undefined();
+    }
    if( ( NonRefType() != REFERENCE_TYPE ) && ( NonRefType() != GENERIC_TYPE ) ) {
        return ptr.u;
    }
@@ -1005,6 +1048,10 @@ SCLundefined * STEPattribute::Undefined() {
 // these set the attr value

 void STEPattribute::Integer( SDAI_Integer * n ) {
+    if( _redefAttr ) {
+        _redefAttr->Integer( n );
+        return;
+    }
    assert( NonRefType() == INTEGER_TYPE );
    if( ptr.i ) {
        *( ptr.i ) = * n;
@@ -1014,6 +1061,10 @@ void STEPattribute::Integer( SDAI_Integer * n ) {
 }

 void STEPattribute::Real( SDAI_Real * n ) {
+    if( _redefAttr ) {
+        _redefAttr->Real( n );
+        return;
+    }
    assert( NonRefType() == REAL_TYPE );
    if( ptr.r ) {
        *( ptr.r ) = * n;
@@ -1023,6 +1074,10 @@ void STEPattribute::Real( SDAI_Real * n ) {
 }

 void STEPattribute::Number( SDAI_Real * n ) {
+    if( _redefAttr ) {
+        _redefAttr->Number( n );
+        return;
+    }
    assert( NonRefType() == NUMBER_TYPE );
    if( ptr.r ) {
        *( ptr.r ) = * n;
@@ -1032,6 +1087,10 @@ void STEPattribute::Number( SDAI_Real * n ) {
 }

 void STEPattribute::String( SDAI_String * str ) {
+    if( _redefAttr ) {
+        _redefAttr->String( str );
+        return;
+    }
    assert( NonRefType() == STRING_TYPE );
    if( ptr.S ) {
        *( ptr.S ) = * str;
@@ -1041,6 +1100,10 @@ void STEPattribute::String( SDAI_String * str ) {
 }

 void STEPattribute::Binary( SDAI_Binary * bin ) {
+    if( _redefAttr ) {
+        _redefAttr->Binary( bin );
+        return;
+    }
    assert( NonRefType() == BINARY_TYPE );
    if( ptr.b ) {
        *( ptr.b ) = * bin;
@@ -1050,15 +1113,25 @@ void STEPattribute::Binary( SDAI_Binary * bin ) {
 }

 void STEPattribute::Entity( SDAI_Application_instance * ent ) {
+    if( _redefAttr ) {
+        _redefAttr->Entity( ent );
+        return;
+    }
    assert( NonRefType() == ENTITY_TYPE );
    if( ptr.c ) {
-        delete ptr.c;
+        *( ptr.c ) = ent;
+    } else {
+        ptr.c = new (SDAI_Application_instance * );
+        _mustDeletePtr = true;
+        *( ptr.c ) = ent;
    }
-    ptr.c = new (SDAI_Application_instance * );
-    *( ptr.c ) = ent;
 }

 void STEPattribute::Aggregate( STEPaggregate * aggr ) {
+    if( _redefAttr ) {
+        _redefAttr->Aggregate( aggr );
+        return;
+    }
    assert( ( NonRefType() == AGGREGATE_TYPE ) || ( NonRefType() == ARRAY_TYPE ) || ( NonRefType() == BAG_TYPE )
    || ( NonRefType() == SET_TYPE ) || ( NonRefType() == LIST_TYPE ) );
    if( ptr.a ) {
@@ -1069,6 +1142,10 @@ void STEPattribute::Aggregate( STEPaggregate * aggr ) {
 }

 void STEPattribute::Enum( SDAI_Enum * enu ) {
+    if( _redefAttr ) {
+        _redefAttr->Enum( enu );
+        return;
+    }
    assert( NonRefType() == ENUM_TYPE );
    if( ptr.e ) {
        ptr.e->set_null();
@@ -1079,6 +1156,10 @@ void STEPattribute::Enum( SDAI_Enum * enu ) {
 }

 void STEPattribute::Logical( SDAI_LOGICAL * log ) {
+    if( _redefAttr ) {
+        _redefAttr->Logical( log );
+        return;
+    }
    assert( NonRefType() == LOGICAL_TYPE );
    if( ptr.e ) {
        ptr.e->set_null();
@@ -1089,6 +1170,10 @@ void STEPattribute::Logical( SDAI_LOGICAL * log ) {
 }

 void STEPattribute::Boolean( SDAI_BOOLEAN * boo ) {
+    if( _redefAttr ) {
+        _redefAttr->Boolean( boo );
+        return;
+    }
    assert( NonRefType() == BOOLEAN_TYPE );
    if( ptr.e ) {
        ptr.e->set_null();
@@ -1099,6 +1184,10 @@ void STEPattribute::Boolean( SDAI_BOOLEAN * boo ) {
 }

 void STEPattribute::Select( SDAI_Select * sel ) {
+    if( _redefAttr ) {
+        _redefAttr->Select( sel );
+        return;
+    }
    assert( NonRefType() == SELECT_TYPE );
    if( ptr.sh ) {
        ptr.sh->set_null();
@@ -1109,6 +1198,10 @@ void STEPattribute::Select( SDAI_Select * sel ) {
 }

 void STEPattribute::Undefined( SCLundefined * undef ) {
+    if( _redefAttr ) {
+        _redefAttr->Undefined( undef );
+        return;
+    }
    //FIXME is this right, or is the Undefined() above right?
    assert( NonRefType() == REFERENCE_TYPE || NonRefType() == UNKNOWN_TYPE );
    if( ptr.u ) {
@@ -1266,15 +1359,15 @@ void STEPattribute::AddErrorInfo() {
    errStr[0] = '\0';
    if( SEVERITY_INPUT_ERROR < _error.severity() &&
            _error.severity() < SEVERITY_NULL ) {
-        sprintf( errStr, " Warning: ATTRIBUTE '%s : %s : %d' - ",
+        snprintf( errStr, sizeof(errStr), " Warning: ATTRIBUTE '%s : %s : %d' - ",
                 Name(), TypeName().c_str(), Type() );
        _error.PrependToDetailMsg( errStr );
    } else if( _error.severity() == SEVERITY_INPUT_ERROR ) {
-        sprintf( errStr, " Error: ATTRIBUTE '%s : %s : %d' - ",
+        snprintf( errStr, sizeof(errStr), " Error: ATTRIBUTE '%s : %s : %d' - ",
                 Name(), TypeName().c_str(), Type() );
        _error.PrependToDetailMsg( errStr );
    } else if( _error.severity() <= SEVERITY_BUG ) {
-        sprintf( errStr, " BUG: ATTRIBUTE '%s : %s : %d' - ",
+        snprintf( errStr, sizeof(errStr), " BUG: ATTRIBUTE '%s : %s : %d' - ",
                 Name(), TypeName().c_str(), Type() );
        _error.PrependToDetailMsg( errStr );
    }
@@ -1302,12 +1395,12 @@ char STEPattribute::SkipBadAttr( istream & in, char * StopChars ) {
    }
    if( in.eof() ) {
        _error.GreaterSeverity( SEVERITY_INPUT_ERROR );
-        sprintf( errStr, " Error: attribute '%s : %s : %d' - %s.\n",
+        snprintf( errStr, sizeof(errStr), " Error: attribute '%s : %s : %d' - %s.\n",
                 Name(), TypeName().c_str(), Type(),
                 "Unexpected EOF when skipping bad attr value" );
        _error.AppendToDetailMsg( errStr );
    } else {
-        sprintf( errStr, " Error: attribute '%s : %s : %d' - %s.\n",
+        snprintf( errStr, sizeof(errStr), " Error: attribute '%s : %s : %d' - %s.\n",
                 Name(), TypeName().c_str(), Type(), "Invalid value" );
        _error.AppendToDetailMsg( errStr );
    }
@@ -1364,6 +1457,71 @@ _redefAttr( a._redefAttr ), aDesc( a.aDesc ), refCount( a.refCount ) {
 */
 }

+STEPattribute::STEPattribute( const class AttrDescriptor & d ) : _derive( false ),
+_mustDeletePtr( true ), _redefAttr( 0 ), aDesc( &d ), refCount( 0 ) {
+    memset( &ptr, 0, sizeof( ptr ) );
+
+    switch( d.NonRefType() ) {
+        case INTEGER_TYPE:
+            ptr.i = new SDAI_Integer;
+            break;
+        case REAL_TYPE:
+        case NUMBER_TYPE:
+            ptr.r = new SDAI_Real;
+            break;
+        case STRING_TYPE:
+            ptr.S = new SDAI_String;
+            break;
+        case BINARY_TYPE:
+            ptr.b = new SDAI_Binary;
+            break;
+        case ENTITY_TYPE:
+            ptr.c = new SDAI_Application_instance *;
+            *ptr.c = 0;
+            break;
+        case BOOLEAN_TYPE:
+            ptr.e = new SDAI_BOOLEAN;
+            break;
+        case LOGICAL_TYPE:
+            ptr.e = new SDAI_LOGICAL;
+            break;
+        case ENUM_TYPE: {
+            const EnumTypeDescriptor * etd =
+                dynamic_cast<const EnumTypeDescriptor *>( d.NonRefTypeDescriptor() );
+            ptr.e = etd ? etd->CreateEnum() : 0;
+            break;
+        }
+        case SELECT_TYPE: {
+            const SelectTypeDescriptor * std =
+                dynamic_cast<const SelectTypeDescriptor *>( d.NonRefTypeDescriptor() );
+            ptr.sh = std ? std->CreateSelect() : 0;
+            if( !ptr.sh && std ) {
+                ptr.sh = new SDAI_Select( std );
+            }
+            break;
+        }
+        case AGGREGATE_TYPE:
+        case ARRAY_TYPE:
+        case BAG_TYPE:
+        case SET_TYPE:
+        case LIST_TYPE: {
+            const AggrTypeDescriptor * atd =
+                dynamic_cast<const AggrTypeDescriptor *>( d.NonRefTypeDescriptor() );
+            ptr.a = atd ? atd->CreateAggregate() : 0;
+            if( !ptr.a ) {
+                ptr.a = new GenericAggregate;
+            }
+            break;
+        }
+        case UNKNOWN_TYPE:
+        case GENERIC_TYPE:
+        case REFERENCE_TYPE:
+        default:
+            ptr.u = new SCLundefined;
+            break;
+    }
+}
+
 ///  INTEGER
 STEPattribute::STEPattribute( const class AttrDescriptor & d, SDAI_Integer * p ): _derive( false ),
 _mustDeletePtr( false ), _redefAttr( 0 ), aDesc( &d ), refCount( 0 )  {
@@ -1427,10 +1585,12 @@ _mustDeletePtr( false ), _redefAttr( 0 ), aDesc( &d ), refCount( 0 )  {
    assert( &d ); //ensure that the AttrDescriptor is not a null pointer
 }

-/// the destructor conditionally deletes the object in ptr
-STEPattribute::~STEPattribute() {
+void STEPattribute::DeleteOwnedPtr() {
    if( _mustDeletePtr ) {
-        switch( NonRefType() ) {
+        // A redefined attribute delegates value operations to _redefAttr, but
+        // ptr still holds storage allocated for this attribute's descriptor.
+        // Use that original type when releasing the owned storage.
+        switch( aDesc ? aDesc->NonRefType() : UNKNOWN_TYPE ) {
            case AGGREGATE_TYPE:
            case ARRAY_TYPE:      // DAS
            case BAG_TYPE:        // DAS
@@ -1453,12 +1613,53 @@ STEPattribute::~STEPattribute() {
                    ptr.e = 0;
                }
                break;
+            case ENUM_TYPE:
+                delete ptr.e;
+                ptr.e = 0;
+                break;
+            case SELECT_TYPE:
+                delete ptr.sh;
+                ptr.sh = 0;
+                break;
+            case STRING_TYPE:
+                delete ptr.S;
+                ptr.S = 0;
+                break;
+            case BINARY_TYPE:
+                delete ptr.b;
+                ptr.b = 0;
+                break;
+            case INTEGER_TYPE:
+                delete ptr.i;
+                ptr.i = 0;
+                break;
+            case REAL_TYPE:
+            case NUMBER_TYPE:
+                delete ptr.r;
+                ptr.r = 0;
+                break;
+            case ENTITY_TYPE:
+                delete ptr.c;
+                ptr.c = 0;
+                break;
+            case UNKNOWN_TYPE:
+            case GENERIC_TYPE:
+            case REFERENCE_TYPE:
+                delete ptr.u;
+                ptr.u = 0;
+                break;
            default:
                break;
        }
+        _mustDeletePtr = false;
    }
 }

+/// the destructor conditionally deletes the object in ptr
+STEPattribute::~STEPattribute() {
+    DeleteOwnedPtr();
+}
+
 /// name is the same even if redefined
 const char * STEPattribute::Name() const {
    return aDesc->Name();
@@ -41,10 +41,14 @@ STEPattribute & STEPattributeList::operator []( int n ) {
        return *( a->attr );
    }

-    // else
+    // else - error case: return a static error object to avoid undefined behavior
+    // The error object allows calling code to detect the error condition
+    static STEPattribute errorAttr;
    cerr << "\nERROR in STEP Core library:  " << __FILE__ <<  ":"
         << __LINE__ << "\n" << _POC_ << "\n\n";
-    return *( STEPattribute * ) 0;
+    errorAttr.Error().AppendToDetailMsg( "STEPattributeList::operator[] - index out of bounds" );
+    errorAttr.Error().severity( SEVERITY_BUG );
+    return errorAttr;
 }

 int STEPattributeList::list_length() {
@@ -661,7 +661,7 @@ void STEPcomplex::CopyAs( SDAI_Application_instance * se ) {
        char errStr[BUFSIZ+1];
        cerr << "STEPcomplex::CopyAs() called with non-complex entity:  "
             << __FILE__ <<  __LINE__ << "\n" << _POC_ "\n";
-        sprintf( errStr,
+        snprintf( errStr, sizeof(errStr),
                 "STEPcomplex::CopyAs(): %s - entity #%d.\n",
                 "Programming ERROR -  called with non-complex entity",
                 STEPfile_id );
@@ -702,7 +702,7 @@ SDAI_Application_instance * STEPcomplex::Replicate() {
            char errStr[BUFSIZ+1];
            cerr << "STEPcomplex::Replicate() name buffer too small:  "
                 << __FILE__ <<  __LINE__ << "\n" << _POC_ "\n";
-            sprintf( errStr,
+            snprintf( errStr, sizeof(errStr),
                     "STEPcomplex::Replicate(): %s - entity #%d.\n",
                     "Programming ERROR - name buffer too small",
                     STEPfile_id );
@@ -1,10 +1,59 @@
 #include "clstepcore/aggrTypeDescriptor.h"

-STEPaggregate * AggrTypeDescriptor::CreateAggregate() {
+#include "clstepcore/STEPaggregate.h"
+#include "clstepcore/enumTypeDescriptor.h"
+#include "clstepcore/selectTypeDescriptor.h"
+
+namespace {
+
+class DescriptorEnumAggregate : public EnumAggregate {
+    const EnumTypeDescriptor * _enumType;
+
+public:
+    explicit DescriptorEnumAggregate( const EnumTypeDescriptor * enumType )
+        : _enumType( enumType ) {
+    }
+
+    virtual SingleLinkNode * NewNode() {
+        return new EnumNode( _enumType ? _enumType->CreateEnum() : 0 );
+    }
+};
+
+}
+
+STEPaggregate * AggrTypeDescriptor::CreateAggregate() const {
    if( CreateNewAggr ) {
        return CreateNewAggr();
-    } else {
-        return 0;
+    }
+
+    const TypeDescriptor * element = ReferentType();
+    const TypeDescriptor * concrete =
+        element ? element->NonRefTypeDescriptor() : 0;
+    const PrimitiveType type = element ? element->NonRefType() : UNKNOWN_TYPE;
+    switch( type ) {
+        case sdaiINSTANCE:
+            return new EntityAggregate;
+        case sdaiSELECT:
+            return new SelectAggregate(
+                dynamic_cast<const SelectTypeDescriptor *>( concrete ) );
+        case sdaiENUMERATION:
+            return new DescriptorEnumAggregate(
+                dynamic_cast<const EnumTypeDescriptor *>( concrete ) );
+        case sdaiBOOLEAN:
+            return new BOOLEANS;
+        case sdaiLOGICAL:
+            return new LOGICALS;
+        case sdaiINTEGER:
+            return new IntAggregate;
+        case sdaiREAL:
+        case sdaiNUMBER:
+            return new RealAggregate;
+        case sdaiSTRING:
+            return new StringAggregate;
+        case sdaiBINARY:
+            return new BinaryAggregate;
+        default:
+            return new GenericAggregate;
    }
 }

@@ -13,18 +62,20 @@ void AggrTypeDescriptor::AssignAggrCreator( AggregateCreator f ) {
 }

 AggrTypeDescriptor::AggrTypeDescriptor( ) :
-_uniqueElements( "UNKNOWN_TYPE" ) {
-    _bound1 = -1;
-    _bound2 = -1;
-    _aggrDomainType = 0;
+    _bound1( -1 ), _bound2( -1 ), _uniqueElements( "UNKNOWN_TYPE" ),
+    _aggrDomainType( 0 ), CreateNewAggr( 0 ),
+    _bound1_type( bound_unset ), _bound2_type( bound_unset ),
+    _bound1_callback( 0 ), _bound2_callback( 0 ) {
 }

 AggrTypeDescriptor::AggrTypeDescriptor( SDAI_Integer  b1,
                                        SDAI_Integer  b2,
                                        Logical uniqElem,
                                        TypeDescriptor * aggrDomType )
-: _bound1( b1 ), _bound2( b2 ), _uniqueElements( uniqElem ) {
-    _aggrDomainType = aggrDomType;
+: _bound1( b1 ), _bound2( b2 ), _uniqueElements( uniqElem ),
+  _aggrDomainType( aggrDomType ), CreateNewAggr( 0 ),
+  _bound1_type( bound_constant ), _bound2_type( bound_constant ),
+  _bound1_callback( 0 ), _bound2_callback( 0 ) {
 }

 AggrTypeDescriptor::~AggrTypeDescriptor() {
@@ -79,14 +79,14 @@ void Schema::GenerateExpress( ostream & out ) const {
    }
    if( !_function_list.empty() ) {
        out << "(* *************FUNCTIONS************* *)" << endl;
-        count = _function_list.size();
+        count = (int)_function_list.size();
        for( i = 0; i <  count; i++ ) {
            out << endl << _function_list[i] << endl;
        }
    }
    if( !_procedure_list.empty() ) {
        out << "(* *************PROCEDURES************* *)" << endl;
-        count = _procedure_list.size();
+        count = (int)_procedure_list.size();
        for( i = 0; i <  count; i++ ) {
            out << endl << _procedure_list[i] << endl;
        }
@@ -1,10 +1,158 @@
+#include <cstring>
+#include <limits>
+#include <mutex>
+#include <set>
 #include <string>
+#include <unordered_map>
+#include <vector>

 #include "clstepcore/entityDescriptor.h"
 #include "clstepcore/Registry.h"
 #include "clstepcore/attrDescriptor.h"
 #include "clstepcore/inverseAttribute.h"
 #include "clstepcore/SubSuperIterators.h"
+#include "clstepcore/STEPattribute.h"
+#include "clstepcore/sdaiApplication_instance.h"
+
+struct EntityAttributeLayoutEntry {
+    explicit EntityAttributeLayoutEntry(
+        const AttrDescriptor * attributeDescriptor )
+        : descriptor( attributeDescriptor ), derived( false ),
+          redefining( std::numeric_limits<size_t>::max() ) {
+    }
+
+    const AttrDescriptor * descriptor;
+    bool derived;
+    size_t redefining;
+};
+
+class EntityAttributeLayout {
+public:
+    EntityAttributeLayout() : hasRedefinitions( false ) {
+    }
+
+    std::vector<EntityAttributeLayoutEntry> attributes;
+    bool hasRedefinitions;
+};
+
+namespace {
+
+const size_t noAttribute = std::numeric_limits<size_t>::max();
+
+class EntityAttributeLayoutCache {
+    typedef std::unordered_map<const EntityDescriptor *,
+            EntityAttributeLayout *> LayoutMap;
+
+    LayoutMap _layouts;
+    std::mutex _mutex;
+
+public:
+    ~EntityAttributeLayoutCache() {
+        for( LayoutMap::iterator i = _layouts.begin();
+             i != _layouts.end(); ++i ) {
+            delete i->second;
+        }
+    }
+
+    EntityAttributeLayout * Find( const EntityDescriptor * entity ) {
+        std::lock_guard<std::mutex> lock( _mutex );
+        LayoutMap::iterator i = _layouts.find( entity );
+        return i == _layouts.end() ? 0 : i->second;
+    }
+
+    void Insert( const EntityDescriptor * entity,
+                 EntityAttributeLayout * layout ) {
+        std::lock_guard<std::mutex> lock( _mutex );
+        LayoutMap::iterator i = _layouts.find( entity );
+        if( i == _layouts.end() ) {
+            _layouts[entity] = layout;
+        } else {
+            delete layout;
+        }
+    }
+
+    void Erase( const EntityDescriptor * entity ) {
+        std::lock_guard<std::mutex> lock( _mutex );
+        LayoutMap::iterator i = _layouts.find( entity );
+        if( i != _layouts.end() ) {
+            delete i->second;
+            _layouts.erase( i );
+        }
+    }
+};
+
+EntityAttributeLayoutCache & layoutCache() {
+    static EntityAttributeLayoutCache cache;
+    return cache;
+}
+
+size_t findAttribute( const EntityAttributeLayout & layout,
+                      const char * name, const char * owner ) {
+    for( size_t i = 0; i < layout.attributes.size(); ++i ) {
+        const AttrDescriptor * candidate = layout.attributes[i].descriptor;
+        if( strcmp( name, candidate->Name() ) == 0 &&
+            ( !owner || candidate->Owner().IsA( owner ) ) ) {
+            return i;
+        }
+    }
+    return noAttribute;
+}
+
+void appendLayout( const EntityDescriptor * ed, EntityAttributeLayout & layout,
+                   std::set<const EntityDescriptor *> & visited ) {
+    if( !ed || !visited.insert( ed ).second ) {
+        return;
+    }
+
+    EntityDescItr supers( ed->Supertypes() );
+    const EntityDescriptor * super = 0;
+    while( ( super = supers.NextEntityDesc() ) ) {
+        appendLayout( super, layout, visited );
+    }
+
+    AttrDescItr attrs( ed->ExplicitAttr() );
+    const AttrDescriptor * ad = 0;
+    while( ( ad = attrs.NextAttrDesc() ) ) {
+        const char * separator = strrchr( ad->Name(), '.' );
+        const char * simpleName = separator ? separator + 1 : ad->Name();
+        if( ad->AttrType() == AttrType_Deriving ) {
+            const char * ownerName = ed->Name();
+            std::string qualifiedOwner;
+            if( separator ) {
+                qualifiedOwner.assign( ad->Name(), separator - ad->Name() );
+                ownerName = qualifiedOwner.c_str();
+            }
+            const size_t target =
+                findAttribute( layout, simpleName, ownerName );
+            if( target != noAttribute ) {
+                layout.attributes[target].derived = true;
+            }
+            continue;
+        }
+        if( ad->AttrType() == AttrType_Inverse ) {
+            continue;
+        }
+
+        layout.attributes.push_back( EntityAttributeLayoutEntry( ad ) );
+        if( ad->AttrType() == AttrType_Redefining ) {
+            const size_t target = findAttribute( layout, simpleName, 0 );
+            if( target != noAttribute ) {
+                layout.attributes[target].redefining =
+                    layout.attributes.size() - 1;
+                layout.hasRedefinitions = true;
+            }
+        }
+    }
+}
+
+class LateBoundEntity : public SDAI_Application_instance {
+public:
+    explicit LateBoundEntity( const EntityDescriptor * ed ) {
+        eDesc = ed;
+    }
+};
+
+}

 EntityDescriptor::EntityDescriptor( )
    : _abstractEntity( LUnknown ), _extMapping( LUnknown ),
@@ -23,9 +171,65 @@ EntityDescriptor::EntityDescriptor( const char * name, // i.e. char *
 }

 EntityDescriptor::~EntityDescriptor() {
+    layoutCache().Erase( this );
    delete _uniqueness_rules;
 }

+SDAI_Application_instance * EntityDescriptor::CreateEntity() const {
+    if( NewSTEPentity ) {
+        return NewSTEPentity();
+    }
+
+    PrepareLateBoundLayout();
+    EntityAttributeLayout * layout = layoutCache().Find( this );
+    LateBoundEntity * entity = new LateBoundEntity( this );
+    std::vector<STEPattribute *> attributes;
+    if( layout->hasRedefinitions ) {
+        attributes.reserve( layout->attributes.size() );
+    }
+    for( size_t i = 0; i < layout->attributes.size(); ++i ) {
+        const EntityAttributeLayoutEntry & entry = layout->attributes[i];
+        STEPattribute * attribute = new STEPattribute( *entry.descriptor );
+        attribute->set_null();
+        if( entry.derived ) {
+            attribute->Derive();
+        }
+        entity->attributes.push( attribute );
+        if( layout->hasRedefinitions ) {
+            attributes.push_back( attribute );
+        }
+    }
+    if( layout->hasRedefinitions ) {
+        for( size_t i = 0; i < layout->attributes.size(); ++i ) {
+            const size_t redefining = layout->attributes[i].redefining;
+            if( redefining != noAttribute ) {
+                attributes[i]->RedefiningAttr( attributes[redefining] );
+            }
+        }
+    }
+    return entity;
+}
+
+void EntityDescriptor::PrepareLateBoundLayout() const {
+    if( layoutCache().Find( this ) ) {
+        return;
+    }
+    EntityAttributeLayout * layout = new EntityAttributeLayout;
+    std::set<const EntityDescriptor *> visited;
+    appendLayout( this, *layout, visited );
+    layoutCache().Insert( this, layout );
+}
+
+void EntityDescriptor::InvalidateLateBoundLayout() const {
+    layoutCache().Erase( this );
+
+    EntityDescItr subtypes( _subtypes );
+    const EntityDescriptor * subtype = 0;
+    while( ( subtype = subtypes.NextEntityDesc() ) ) {
+        subtype->InvalidateLateBoundLayout();
+    }
+}
+
 // initialize one inverse attr; used in InitIAttrs, below
 void initIAttr( Inverse_attribute * ia, Registry & reg, const char * schNm, const char * name ) {
    const AttrDescriptor * ad;
@@ -1,5 +1,103 @@
 #include "clstepcore/enumTypeDescriptor.h"

+#include <cctype>
+#include <cstring>
+#include <mutex>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+namespace {
+
+typedef std::vector<std::string> EnumElements;
+typedef std::unordered_map<const EnumTypeDescriptor *, EnumElements>
+    EnumElementMap;
+
+EnumElementMap & enumElementMap() {
+    static EnumElementMap elements;
+    return elements;
+}
+
+std::mutex & enumElementMutex() {
+    static std::mutex mutex;
+    return mutex;
+}
+
+EnumElements parseEnumDescription( const char * description ) {
+    EnumElements result;
+    if( !description ) {
+        return result;
+    }
+    const char * begin = strchr( description, '(' );
+    const char * end = strrchr( description, ')' );
+    if( !begin || !end || begin >= end ) {
+        return result;
+    }
+    ++begin;
+    while( begin < end ) {
+        while( begin < end &&
+                ( std::isspace( static_cast<unsigned char>( *begin ) ) ||
+                  *begin == ',' ) ) {
+            ++begin;
+        }
+        const char * itemEnd = begin;
+        while( itemEnd < end && *itemEnd != ',' ) {
+            ++itemEnd;
+        }
+        const char * trimmed = itemEnd;
+        while( trimmed > begin &&
+                std::isspace( static_cast<unsigned char>( trimmed[-1] ) ) ) {
+            --trimmed;
+        }
+        if( trimmed > begin ) {
+            std::string item( begin, trimmed );
+            for( size_t i = 0; i < item.size(); ++i ) {
+                item[i] = static_cast<char>( std::toupper(
+                    static_cast<unsigned char>( item[i] ) ) );
+            }
+            result.push_back( item );
+        }
+        begin = itemEnd + ( itemEnd < end ? 1 : 0 );
+    }
+    return result;
+}
+
+EnumElements descriptorElements( const EnumTypeDescriptor & descriptor ) {
+    std::lock_guard<std::mutex> lock( enumElementMutex() );
+    EnumElementMap::const_iterator i = enumElementMap().find( &descriptor );
+    if( i != enumElementMap().end() ) {
+        return i->second;
+    }
+    return parseEnumDescription( descriptor.Description() );
+}
+
+class DescriptorEnum : public SDAI_Enum {
+    std::string _name;
+    EnumElements _elements;
+
+public:
+    explicit DescriptorEnum( const EnumTypeDescriptor & descriptor )
+        : _name( descriptor.Name() ),
+          _elements( descriptorElements( descriptor ) ) {
+        nullify();
+    }
+
+    virtual int no_elements() const {
+        return static_cast<int>( _elements.size() );
+    }
+
+    virtual const char * Name() const {
+        return _name.c_str();
+    }
+
+    virtual const char * element_at( int index ) const {
+        return index >= 0 && static_cast<size_t>( index ) < _elements.size() ?
+            _elements[index].c_str() : "UNSET";
+    }
+};
+
+}
+
 /*
 * why have EnumTypeDescriptor + EnumerationTypeDescriptor ???
 * this was in ExpDict.cc before splitting it up
@@ -16,12 +114,34 @@ EnumTypeDescriptor::EnumTypeDescriptor( const char * nm, PrimitiveType ft,
    : TypeDescriptor( nm, ft, origSchema, d ), CreateNewEnum( f ) {
 }

-SDAI_Enum * EnumTypeDescriptor::CreateEnum() {
+SDAI_Enum * EnumTypeDescriptor::CreateEnum() const {
    if( CreateNewEnum ) {
        return CreateNewEnum();
-    } else {
-        return 0;
    }
+    if( NonRefType() == sdaiBOOLEAN ) {
+        return new SDAI_BOOLEAN;
+    }
+    if( NonRefType() == sdaiLOGICAL ) {
+        return new SDAI_LOGICAL;
+    }
+    return new DescriptorEnum( *this );
+}
+
+EnumTypeDescriptor::~EnumTypeDescriptor() {
+    std::lock_guard<std::mutex> lock( enumElementMutex() );
+    enumElementMap().erase( this );
+}
+
+void RegisterEnumDescriptorElements(
+    const EnumTypeDescriptor & descriptor,
+    const char * const * elements, size_t count ) {
+    EnumElements values;
+    values.reserve( count );
+    for( size_t i = 0; i < count; ++i ) {
+        values.push_back( elements[i] ? elements[i] : "" );
+    }
+    std::lock_guard<std::mutex> lock( enumElementMutex() );
+    enumElementMap()[&descriptor].swap( values );
 }

 const char * EnumTypeDescriptor::GenerateExpress( std::string & buf ) const {
@@ -115,11 +115,11 @@ InstMgr::VerifyInstances( ErrorDescriptor & err ) {
        if( !mn ) {
            ++errorCount;
            if( errorCount == 1 )
-                sprintf( errbuf,
+                snprintf( errbuf, sizeof(errbuf),
                         "VerifyInstances: Unable to verify the following instances: node %d",
                         i );
            else {
-                sprintf( errbuf, ", node %d", i );
+                snprintf( errbuf, sizeof(errbuf), ", node %d", i );
            }

            err.AppendToDetailMsg( errbuf );
@@ -139,18 +139,18 @@ InstMgr::VerifyInstances( ErrorDescriptor & err ) {
                }
                ++errorCount;
                if( errorCount == 1 )
-                    sprintf( errbuf,
+                    snprintf( errbuf, sizeof(errbuf),
                             "VerifyInstances: Unable to verify the following instances: #%d",
                             se->StepFileId() );
                else {
-                    sprintf( errbuf, ", #%d", se->StepFileId() );
+                    snprintf( errbuf, sizeof(errbuf), ", #%d", se->StepFileId() );
                }
                err.AppendToDetailMsg( errbuf );
            }
        }
    }
    if( errorCount ) {
-        sprintf( errbuf,
+        snprintf( errbuf, sizeof(errbuf),
                 "VerifyInstances: %d invalid instances in list.\n",
                 errorCount );
        err.AppendToUserMsg( errbuf );
@@ -153,7 +153,7 @@ std::string WriteReal( SDAI_Real val ) {
    // Also use G instead of g since G writes uppercase E (E instead of e
    // is also required by Part 21) when scientific notation is used - DAS

-    sprintf( rbuf, "%.*G", ( int ) RealNumPrecision, val );
+    snprintf( rbuf, sizeof(rbuf), "%.*G", ( int ) RealNumPrecision, val );
    if( !strchr( rbuf, '.' ) ) {
        if( strchr( rbuf, 'E' ) || strchr( rbuf, 'e' ) ) {
            char * expon = strchr( rbuf, 'E' );
@@ -168,7 +168,7 @@ std::string WriteReal( SDAI_Real val ) {
            expon++;
            s += expon;
        } else {
-            int rindex = strlen( rbuf );
+            int rindex = (int)strlen( rbuf );
            rbuf[rindex] = '.';
            rbuf[rindex + 1] = '\0';
            s = rbuf;
@@ -490,7 +490,7 @@ void PushPastImbedAggr( istream & in, std::string & s, ErrorDescriptor * err ) {
        }
        if( c != ')' ) {
            err->GreaterSeverity( SEVERITY_INPUT_ERROR );
-            sprintf( messageBuf, "Invalid aggregate value.\n" );
+            snprintf( messageBuf, sizeof(messageBuf), "Invalid aggregate value.\n" );
            err->AppendToDetailMsg( messageBuf );
            s.append( ")" );
        } else {
@@ -518,7 +518,7 @@ void PushPastAggr1Dim( istream & in, std::string & s, ErrorDescriptor * err ) {
        while( in.good() && ( c != ')' ) ) {
            if( c == '(' ) {
                err->GreaterSeverity( SEVERITY_WARNING );
-                sprintf( messageBuf, "Invalid aggregate value.\n" );
+                snprintf( messageBuf, sizeof(messageBuf), "Invalid aggregate value.\n" );
                err->AppendToDetailMsg( messageBuf );
            }

@@ -532,7 +532,7 @@ void PushPastAggr1Dim( istream & in, std::string & s, ErrorDescriptor * err ) {
        }
        if( c != ')' ) {
            err->GreaterSeverity( SEVERITY_INPUT_ERROR );
-            sprintf( messageBuf, "Invalid aggregate value.\n" );
+            snprintf( messageBuf, sizeof(messageBuf), "Invalid aggregate value.\n" );
            err->AppendToDetailMsg( messageBuf );
            s.append( ")" );
        } else {
@@ -0,0 +1,317 @@
+#include "clstepcore/schemaModule.h"
+
+#include <cassert>
+#include <unordered_map>
+
+#include "clstepcore/attrDescriptor.h"
+#include "clstepcore/aggrTypeDescriptor.h"
+#include "clstepcore/derivedAttribute.h"
+#include "clstepcore/dictSchema.h"
+#include "clstepcore/entityDescriptor.h"
+#include "clstepcore/enumTypeDescriptor.h"
+#include "clstepcore/inverseAttribute.h"
+#include "clstepcore/selectTypeDescriptor.h"
+#include "clstepcore/typeDescriptor.h"
+
+namespace {
+
+struct PendingSchemaModule {
+    std::vector<const EntityDescriptor *> entities;
+    std::vector<const TypeDescriptor *> types;
+    std::vector<const AttrDescriptor *> attributes;
+};
+
+class PendingSchemaModules {
+    typedef std::unordered_map<const Schema *, PendingSchemaModule> ModuleMap;
+
+    ModuleMap _modules;
+    const Schema * _lastSchema;
+    PendingSchemaModule * _lastModule;
+
+    PendingSchemaModule * Find( Schema & schema ) {
+        if( _lastSchema == &schema ) {
+            return _lastModule;
+        }
+        ModuleMap::iterator i = _modules.find( &schema );
+        _lastSchema = &schema;
+        _lastModule = i == _modules.end() ? 0 : &i->second;
+        return _lastModule;
+    }
+
+public:
+    PendingSchemaModules() : _lastSchema( 0 ), _lastModule( 0 ) {
+    }
+
+    void Begin( Schema & schema ) {
+        PendingSchemaModule & module = _modules[&schema];
+        module.entities.clear();
+        module.types.clear();
+        module.attributes.clear();
+        _lastSchema = &schema;
+        _lastModule = &module;
+    }
+
+    void RecordEntity( Schema & schema, const EntityDescriptor * entity ) {
+        PendingSchemaModule * module = Find( schema );
+        if( module ) {
+            module->entities.push_back( entity );
+        }
+    }
+
+    void RecordType( Schema & schema, const TypeDescriptor * type ) {
+        PendingSchemaModule * module = Find( schema );
+        if( module ) {
+            module->types.push_back( type );
+        }
+    }
+
+    void RecordAttribute( Schema & schema, const AttrDescriptor * attribute ) {
+        PendingSchemaModule * module = Find( schema );
+        if( module ) {
+            module->attributes.push_back( attribute );
+        }
+    }
+
+    bool Consume( Schema & schema, PendingSchemaModule & module ) {
+        ModuleMap::iterator i = _modules.find( &schema );
+        if( i == _modules.end() ) {
+            return false;
+        }
+        module.entities.swap( i->second.entities );
+        module.types.swap( i->second.types );
+        module.attributes.swap( i->second.attributes );
+        if( _lastSchema == &schema ) {
+            _lastSchema = 0;
+            _lastModule = 0;
+        }
+        _modules.erase( i );
+        return true;
+    }
+};
+
+PendingSchemaModules & pendingSchemaModules() {
+    static PendingSchemaModules modules;
+    return modules;
+}
+
+const TypeDescriptor * typeFromSlot( const SchemaModuleSlot & record ) {
+    switch( record.kind ) {
+        case SchemaModuleSlot_EnumType:
+            return *static_cast<EnumTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_SelectType:
+            return *static_cast<SelectTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_AggregateType:
+            return *static_cast<AggrTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_ArrayType:
+            return *static_cast<ArrayTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_ListType:
+            return *static_cast<ListTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_SetType:
+            return *static_cast<SetTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_BagType:
+            return *static_cast<BagTypeDescriptor * const *>( record.slot );
+        case SchemaModuleSlot_Type:
+        default:
+            return *static_cast<TypeDescriptor * const *>( record.slot );
+    }
+}
+
+const AttrDescriptor * attributeFromSlot( const SchemaModuleSlot & record ) {
+    switch( record.kind ) {
+        case SchemaModuleSlot_DerivedAttribute:
+            return *static_cast<Derived_attribute * const *>( record.slot );
+        case SchemaModuleSlot_InverseAttribute:
+            return *static_cast<Inverse_attribute * const *>( record.slot );
+        case SchemaModuleSlot_Attribute:
+        default:
+            return *static_cast<AttrDescriptor * const *>( record.slot );
+    }
+}
+
+void prepareLateBoundLayouts(
+    const std::vector<const EntityDescriptor *> & entities ) {
+    for( size_t i = 0; i < entities.size(); ++i ) {
+        if( entities[i] && !entities[i]->NewSTEPentity ) {
+            entities[i]->PrepareLateBoundLayout();
+        }
+    }
+}
+
+}
+
+class SchemaLoadContext::Impl {
+public:
+    typedef std::unordered_map<const Schema *, PendingSchemaModule> ModuleMap;
+    ModuleMap modules;
+};
+
+SchemaLoadContext::SchemaLoadContext() : _impl( new Impl ) {
+}
+
+SchemaLoadContext::~SchemaLoadContext() {
+    delete _impl;
+}
+
+void SchemaLoadContext::Begin( Schema & schema ) {
+    PendingSchemaModule & module = _impl->modules[&schema];
+    module.entities.clear();
+    module.types.clear();
+    module.attributes.clear();
+}
+
+void SchemaLoadContext::RecordEntity(
+    Schema & schema, const EntityDescriptor * entity ) {
+    _impl->modules[&schema].entities.push_back( entity );
+}
+
+void SchemaLoadContext::RecordType(
+    Schema & schema, const TypeDescriptor * type ) {
+    _impl->modules[&schema].types.push_back( type );
+}
+
+void SchemaLoadContext::RecordAttribute(
+    Schema & schema, const AttrDescriptor * attribute ) {
+    _impl->modules[&schema].attributes.push_back( attribute );
+}
+
+void BeginSchemaModuleImage( Schema & schema ) {
+    pendingSchemaModules().Begin( schema );
+}
+
+void RecordSchemaModuleEntity( Schema & schema,
+                               const EntityDescriptor * entity ) {
+    pendingSchemaModules().RecordEntity( schema, entity );
+}
+
+void RecordSchemaModuleType( Schema & schema, const TypeDescriptor * type ) {
+    pendingSchemaModules().RecordType( schema, type );
+}
+
+void RecordSchemaModuleAttribute( Schema & schema,
+                                  const AttrDescriptor * attribute ) {
+    pendingSchemaModules().RecordAttribute( schema, attribute );
+}
+
+SchemaModule::SchemaModule() : _schema( 0 ), _fingerprint( 0 ) {
+}
+
+SchemaModule::~SchemaModule() {
+}
+
+void SchemaModule::Initialize(
+    Schema & schema,
+    const EntityDescriptor * const * entities, size_t entityCount,
+    const TypeDescriptor * const * types, size_t typeCount,
+    const AttrDescriptor * const * attributes, size_t attributeCount ) {
+    _schema = &schema;
+    _fingerprint = 0;
+    _entities.assign( entities, entities + entityCount );
+    _types.assign( types, types + typeCount );
+    _attributes.assign( attributes, attributes + attributeCount );
+    prepareLateBoundLayouts( _entities );
+}
+
+void SchemaModule::InitializeFromSlots(
+    Schema & schema,
+    const SchemaModuleSlot * entities, size_t entityCount,
+    const SchemaModuleSlot * types, size_t typeCount,
+    const SchemaModuleSlot * attributes, size_t attributeCount ) {
+    _schema = &schema;
+    _fingerprint = 0;
+    _entities.clear();
+    _entities.reserve( entityCount );
+    for( size_t i = 0; i < entityCount; ++i ) {
+        _entities.push_back(
+            *static_cast<EntityDescriptor * const *>( entities[i].slot ) );
+    }
+    _types.clear();
+    _types.reserve( typeCount );
+    for( size_t i = 0; i < typeCount; ++i ) {
+        _types.push_back( typeFromSlot( types[i] ) );
+    }
+    _attributes.clear();
+    _attributes.reserve( attributeCount );
+    for( size_t i = 0; i < attributeCount; ++i ) {
+        _attributes.push_back( attributeFromSlot( attributes[i] ) );
+    }
+    prepareLateBoundLayouts( _entities );
+}
+
+void SchemaModule::InitializeFromImage( Schema & schema,
+                                        const SchemaModuleImage & image ) {
+    PendingSchemaModule module;
+    const bool found = pendingSchemaModules().Consume( schema, module );
+    const bool valid = found &&
+        image.version == SchemaModuleImageVersion_1 &&
+        module.entities.size() == image.entityCount &&
+        module.types.size() == image.typeCount &&
+        module.attributes.size() == image.attributeCount;
+    assert( valid );
+    if( !valid ) {
+        _schema = 0;
+        _entities.clear();
+        _types.clear();
+        _attributes.clear();
+        return;
+    }
+    _schema = &schema;
+    _fingerprint = 0;
+    _entities.swap( module.entities );
+    _types.swap( module.types );
+    _attributes.swap( module.attributes );
+    prepareLateBoundLayouts( _entities );
+}
+
+bool SchemaModule::InitializeFromContext(
+    Schema & schema, SchemaLoadContext & context, uint64_t fingerprint ) {
+    SchemaLoadContext::Impl::ModuleMap::iterator i =
+        context._impl->modules.find( &schema );
+    if( i == context._impl->modules.end() ) {
+        return false;
+    }
+    _schema = &schema;
+    _entities.swap( i->second.entities );
+    _types.swap( i->second.types );
+    _attributes.swap( i->second.attributes );
+    _fingerprint = fingerprint;
+    context._impl->modules.erase( i );
+    prepareLateBoundLayouts( _entities );
+    return true;
+}
+
+bool SchemaModule::IsInitialized() const {
+    return _schema != 0;
+}
+
+const Schema & SchemaModule::GetSchema() const {
+    assert( _schema );
+    return *_schema;
+}
+
+const EntityDescriptor * SchemaModule::Entity( size_t id ) const {
+    return id < _entities.size() ? _entities[id] : 0;
+}
+
+const TypeDescriptor * SchemaModule::Type( size_t id ) const {
+    return id < _types.size() ? _types[id] : 0;
+}
+
+const AttrDescriptor * SchemaModule::Attribute( size_t id ) const {
+    return id < _attributes.size() ? _attributes[id] : 0;
+}
+
+size_t SchemaModule::EntityCount() const {
+    return _entities.size();
+}
+
+size_t SchemaModule::TypeCount() const {
+    return _types.size();
+}
+
+size_t SchemaModule::AttributeCount() const {
+    return _attributes.size();
+}
+
+uint64_t SchemaModule::Fingerprint() const {
+    return _fingerprint;
+}
@@ -106,7 +106,7 @@ SDAI_Application_instance * SDAI_Application_instance::Replicate() {
    if( IsComplex() ) {
        cerr << "STEPcomplex::Replicate() should be called:  " << __FILE__
             <<  __LINE__ << "\n" << _POC_ "\n";
-        sprintf( errStr,
+        snprintf( errStr, sizeof(errStr),
                 "SDAI_Application_instance::Replicate(): %s - entity #%d.\n",
                 "Programming ERROR - STEPcomplex::Replicate() should be called",
                 STEPfile_id );
@@ -119,7 +119,10 @@ SDAI_Application_instance * SDAI_Application_instance::Replicate() {
            return S_ENTITY_NULL;
        }

-        SDAI_Application_instance * seNew = eDesc->NewSTEPentity();
+        SDAI_Application_instance * seNew = eDesc->CreateEntity();
+        if( !seNew ) {
+            return S_ENTITY_NULL;
+        }
        seNew -> CopyAs( this );
        return seNew;
    }
@@ -151,7 +154,7 @@ void SDAI_Application_instance::STEPwrite_reference( ostream & out ) {

 const char * SDAI_Application_instance::STEPwrite_reference( std::string & buf ) {
    char tmp[64];
-    sprintf( tmp, "#%d", STEPfile_id );
+    snprintf( tmp, sizeof(tmp), "#%d", STEPfile_id );
    buf = tmp;
    return const_cast<char *>( buf.c_str() );
 }
@@ -419,7 +422,7 @@ const char * SDAI_Application_instance::STEPwrite( std::string & buf, const char
    char instanceInfo[BUFSIZ+1];

    std::string tmp;
-    sprintf( instanceInfo, "#%d=%s(", STEPfile_id, StrToUpper( EntityName( currSch ), tmp ) );
+    snprintf( instanceInfo, sizeof(instanceInfo), "#%d=%s(", STEPfile_id, StrToUpper( EntityName( currSch ), tmp ) );
    buf.append( instanceInfo );

    int n = attributes.list_length();
@@ -443,7 +446,7 @@ void SDAI_Application_instance::PrependEntityErrMsg() {

    if( _error.severity() == SEVERITY_NULL ) {
        //  if there is not an error already
-        sprintf( errStr, "\nERROR:  ENTITY #%d %s\n", GetFileId(),
+        snprintf( errStr, sizeof(errStr), "\nERROR:  ENTITY #%d %s\n", GetFileId(),
                 EntityName() );
        _error.PrependToDetailMsg( errStr );
    }
@@ -464,14 +467,14 @@ void SDAI_Application_instance::STEPread_error( char c, int i, istream & in, con

    if( _error.severity() == SEVERITY_NULL ) {
        //  if there is not an error already
-        sprintf( errStr, "\nERROR:  ENTITY #%d %s\n", GetFileId(),
+        snprintf( errStr, sizeof(errStr), "\nERROR:  ENTITY #%d %s\n", GetFileId(),
                 EntityName() );
        _error.PrependToDetailMsg( errStr );
    }

    if( ( i >= 0 ) && ( i < attributes.list_length() ) ) { // i is an attribute
        Error().GreaterSeverity( SEVERITY_WARNING );
-        sprintf( errStr, "  invalid data before type \'%s\'\n",
+        snprintf( errStr, sizeof(errStr), "  invalid data before type \'%s\'\n",
                 attributes[i].TypeName().c_str() );
        _error.AppendToDetailMsg( errStr );
    } else {
@@ -487,7 +490,7 @@ void SDAI_Application_instance::STEPread_error( char c, int i, istream & in, con
    _error.AppendToDetailMsg( c );
    _error.AppendToDetailMsg( '\n' );

-    sprintf( errStr, "\nfinished reading #%d\n", STEPfile_id );
+    snprintf( errStr, sizeof(errStr), "\nfinished reading #%d\n", STEPfile_id );
    _error.AppendToDetailMsg( errStr );
    return;
 }
@@ -552,7 +555,7 @@ Severity SDAI_Application_instance::STEPread( int id,  int idIncr,

                    // set the severity for this entity
                    _error.GreaterSeverity( severe );
-                    sprintf( errStr, "  %s :  ", attributes[i].Name() );
+                    snprintf( errStr, sizeof(errStr), "  %s :  ", attributes[i].Name() );
                    _error.AppendToDetailMsg( errStr ); // add attr name
                    _error.AppendToDetailMsg(
                        "Since using pre-technical corrigendum... missing asterisk for redefined attr.\n" );
@@ -565,9 +568,6 @@ Severity SDAI_Application_instance::STEPread( int id,  int idIncr,
                if( c == ')' ) { // assume you are at the end so read last char
                    in >> c;
                }
-                cout << "Entity #" << STEPfile_id
-                     << " skipping redefined attribute "
-                     << attributes[i].aDesc->Name() << endl << endl << flush;
            }
            // increment counter to read following attr since these attrs
            // aren't written or read => there won't be a delimiter either
@@ -583,7 +583,7 @@ Severity SDAI_Application_instance::STEPread( int id,  int idIncr,

                // set the severity for this entity
                _error.GreaterSeverity( severe );
-                sprintf( errStr, "  %s :  ", attributes[i].Name() );
+                snprintf( errStr, sizeof(errStr), "  %s :  ", attributes[i].Name() );
                _error.AppendToDetailMsg( errStr ); // add attr name
                _error.AppendToDetailMsg( attributes[i].Error().DetailMsg() );  // add attr error
                _error.AppendToUserMsg( attributes[i].Error().UserMsg() );
@@ -653,7 +653,7 @@ Severity SDAI_Application_instance::STEPread( int id,  int idIncr,
        }
    }
    _error.AppendToDetailMsg( tmp.c_str() );
-    sprintf( errStr, "\nfinished reading #%d\n", STEPfile_id );
+    snprintf( errStr, sizeof(errStr), "\nfinished reading #%d\n", STEPfile_id );
    _error.AppendToDetailMsg( errStr );
 // end of imported code
    return _error.severity();
@@ -673,12 +673,14 @@ SDAI_Application_instance * ReadEntityRef( istream & in, ErrorDescriptor * err,
            err->AppendToDetailMsg( "Use of @ instead of # to identify entity.\n" );
            err->GreaterSeverity( SEVERITY_WARNING );
            // no break statement here on purpose
+#if defined(__GNUC__) || defined(__clang__)
            [[gnu::fallthrough]];
+#endif
        case '#': {
            int id = -1;
            in >>  id;
            if( in.fail() ) { //  there's been an error in input
-                sprintf( errStr, "Invalid entity reference value.\n" );
+                snprintf( errStr, sizeof(errStr), "Invalid entity reference value.\n" );
                err->AppendToDetailMsg( errStr );
                err->AppendToUserMsg( errStr );
                err->GreaterSeverity( SEVERITY_WARNING );
@@ -692,7 +694,7 @@ SDAI_Application_instance * ReadEntityRef( istream & in, ErrorDescriptor * err,
                if( !instances ) {
                    cerr << "Internal error:  " << __FILE__ <<  __LINE__
                         << "\n" << _POC_ "\n";
-                    sprintf( errStr,
+                    snprintf( errStr, sizeof(errStr),
                             "STEPread_reference(): %s - entity #%d %s.\n",
                             "BUG - cannot read reference without the InstMgr",
                             id, "is unknown" );
@@ -714,7 +716,7 @@ SDAI_Application_instance * ReadEntityRef( istream & in, ErrorDescriptor * err,
                    } else {
                        cerr << "Internal error:  " << __FILE__ <<  __LINE__
                             << "\n" << _POC_ "\n";
-                        sprintf( errStr,
+                        snprintf( errStr, sizeof(errStr),
                                 "STEPread_reference(): %s - entity #%d %s.\n",
                                 "BUG - MgrNode::GetSTEPentity returned NULL pointer",
                                 id, "is unknown" );
@@ -724,7 +726,7 @@ SDAI_Application_instance * ReadEntityRef( istream & in, ErrorDescriptor * err,
                        return S_ENTITY_NULL;
                    }
                } else {
-                    sprintf( errStr, "Reference to non-existent ENTITY #%d.\n",
+                    snprintf( errStr, sizeof(errStr), "Reference to non-existent ENTITY #%d.\n",
                             id );
                    err->AppendToDetailMsg( errStr );
                    err->AppendToUserMsg( errStr );
@@ -761,7 +763,7 @@ Severity EntityValidLevel( SDAI_Application_instance * se,

    if( !ed || ( ed->NonRefType() != ENTITY_TYPE ) ) {
        err->GreaterSeverity( SEVERITY_BUG );
-        sprintf( messageBuf,
+        snprintf( messageBuf, sizeof(messageBuf),
                 " BUG: EntityValidLevel() called with %s",
                 "missing or invalid EntityDescriptor\n" );
        err->AppendToUserMsg( messageBuf );
@@ -772,7 +774,7 @@ Severity EntityValidLevel( SDAI_Application_instance * se,
    }
    if( !se || ( se == S_ENTITY_NULL ) ) {
        err->GreaterSeverity( SEVERITY_BUG );
-        sprintf( messageBuf,
+        snprintf( messageBuf, sizeof(messageBuf),
                 " BUG: EntityValidLevel() called with null pointer %s\n",
                 "for SDAI_Application_instance argument." );
        err->AppendToUserMsg( messageBuf );
@@ -800,7 +802,7 @@ Severity EntityValidLevel( SDAI_Application_instance * se,
                }
            }
            err->GreaterSeverity( SEVERITY_WARNING );
-            sprintf( messageBuf,
+            snprintf( messageBuf, sizeof(messageBuf),
                     " Entity #%d exists but is not a %s or descendant.\n",
                     se->STEPfile_id, ed->Name() );
            err->AppendToUserMsg( messageBuf );
@@ -809,7 +811,7 @@ Severity EntityValidLevel( SDAI_Application_instance * se,
        }
    } else {
        err->GreaterSeverity( SEVERITY_BUG );
-        sprintf( messageBuf,
+        snprintf( messageBuf, sizeof(messageBuf),
                 " BUG: EntityValidLevel(): SDAI_Application_instance #%d has a %s",
                 se->STEPfile_id, "missing or invalid EntityDescriptor\n" );
        err->AppendToUserMsg( messageBuf );
@@ -893,7 +895,7 @@ Severity EntityValidLevel( const char * attrValue, // string contain entity ref
            SDAI_Application_instance * se = mn->GetSTEPentity();
            return EntityValidLevel( se, ed, err );
        } else {
-            sprintf( messageBuf,
+            snprintf( messageBuf, sizeof(messageBuf),
                     " Attribute's Entity Reference %s does not exist.\n",
                     attrValue );
            err->AppendToUserMsg( messageBuf );
@@ -908,7 +910,7 @@ Severity EntityValidLevel( const char * attrValue, // string contain entity ref
        return err->severity();
    }

-    sprintf( messageBuf, "Invalid attribute entity reference value: '%s'.\n",
+    snprintf( messageBuf, sizeof(messageBuf), "Invalid attribute entity reference value: '%s'.\n",
             attrValue );
    err->AppendToUserMsg( messageBuf );
    err->AppendToDetailMsg( messageBuf );
@@ -16,33 +16,218 @@
 #include <string>
 #include "clstepcore/sdai.h"
 #include "clstepcore/STEPattribute.h"
+#include "clstepcore/STEPaggregate.h"
+#include "clstepcore/read_func.h"

 #ifdef  SC_LOGGING
 #include <fstream.h>
 extern ofstream * logStream;
 #endif

+class SDAI_Select::Storage {
+public:
+    const TypeDescriptor * type;
+    SDAI_Integer integer_value;
+    SDAI_Real real_value;
+    SDAI_Application_instance * entity_value;
+    SDAI_String * string_value;
+    SDAI_Binary * binary_value;
+    SDAI_Enum * enum_value;
+    SDAI_Select * select_value;
+    STEPaggregate * aggregate_value;
+
+    Storage()
+        : type( 0 ), integer_value( 0 ), real_value( 0.0 ), entity_value( 0 ),
+          string_value( 0 ), binary_value( 0 ), enum_value( 0 ),
+          select_value( 0 ), aggregate_value( 0 ) {
+    }
+
+    ~Storage() {
+        Clear();
+    }
+
+    void Clear() {
+        delete string_value;
+        delete binary_value;
+        delete enum_value;
+        delete select_value;
+        delete aggregate_value;
+        type = 0;
+        integer_value = 0;
+        real_value = 0.0;
+        entity_value = 0;
+        string_value = 0;
+        binary_value = 0;
+        enum_value = 0;
+        select_value = 0;
+        aggregate_value = 0;
+    }
+
+    bool Reset( const TypeDescriptor * td ) {
+        Clear();
+        if( !td ) {
+            return true;
+        }
+
+        type = td;
+        const TypeDescriptor * concrete = td->NonRefTypeDescriptor();
+        switch( td->NonRefType() ) {
+            case sdaiSTRING:
+                string_value = new SDAI_String;
+                break;
+            case sdaiBINARY:
+                binary_value = new SDAI_Binary;
+                break;
+            case sdaiBOOLEAN:
+                enum_value = new SDAI_BOOLEAN;
+                break;
+            case sdaiLOGICAL:
+                enum_value = new SDAI_LOGICAL;
+                break;
+            case sdaiENUMERATION: {
+                const EnumTypeDescriptor * enum_type =
+                    dynamic_cast<const EnumTypeDescriptor *>( concrete );
+                enum_value = enum_type ? enum_type->CreateEnum() : 0;
+                break;
+            }
+            case sdaiSELECT: {
+                const SelectTypeDescriptor * select_type =
+                    dynamic_cast<const SelectTypeDescriptor *>( concrete );
+                select_value = select_type ? select_type->CreateSelect() : 0;
+                if( !select_value && select_type ) {
+                    select_value = new SDAI_Select( select_type );
+                }
+                break;
+            }
+            case sdaiAGGR:
+            case ARRAY_TYPE:
+            case BAG_TYPE:
+            case SET_TYPE:
+            case LIST_TYPE: {
+                const AggrTypeDescriptor * aggregate_type =
+                    dynamic_cast<const AggrTypeDescriptor *>( concrete );
+                aggregate_value = aggregate_type ? aggregate_type->CreateAggregate() : 0;
+                break;
+            }
+            default:
+                break;
+        }
+
+        if( ( td->NonRefType() == sdaiENUMERATION && !enum_value ) ||
+                ( td->NonRefType() == sdaiSELECT && !select_value ) ||
+                ( td->IsAggrType() && !aggregate_value ) ) {
+            Clear();
+            return false;
+        }
+        return true;
+    }
+
+    bool CopyFrom( const Storage & other ) {
+        if( !Reset( other.type ) ) {
+            return false;
+        }
+        if( !type ) {
+            return true;
+        }
+        switch( type->NonRefType() ) {
+            case sdaiINTEGER:
+                integer_value = other.integer_value;
+                break;
+            case sdaiREAL:
+            case sdaiNUMBER:
+                real_value = other.real_value;
+                break;
+            case sdaiINSTANCE:
+                entity_value = other.entity_value;
+                break;
+            case sdaiSTRING:
+                *string_value = *other.string_value;
+                break;
+            case sdaiBINARY:
+                *binary_value = *other.binary_value;
+                break;
+            case sdaiBOOLEAN:
+            case sdaiLOGICAL:
+            case sdaiENUMERATION:
+                *enum_value = *other.enum_value;
+                break;
+            case sdaiSELECT:
+                *select_value = *other.select_value;
+                break;
+            case sdaiAGGR:
+            case ARRAY_TYPE:
+            case BAG_TYPE:
+            case SET_TYPE:
+            case LIST_TYPE:
+                aggregate_value->ShallowCopy( *other.aggregate_value );
+                break;
+            default:
+                break;
+        }
+        return true;
+    }
+
+    void * Address() {
+        if( !type ) {
+            return 0;
+        }
+        switch( type->NonRefType() ) {
+            case sdaiINTEGER:
+                return &integer_value;
+            case sdaiREAL:
+            case sdaiNUMBER:
+                return &real_value;
+            case sdaiINSTANCE:
+                return entity_value;
+            case sdaiSTRING:
+                return string_value;
+            case sdaiBINARY:
+                return binary_value;
+            case sdaiBOOLEAN:
+            case sdaiLOGICAL:
+            case sdaiENUMERATION:
+                return enum_value;
+            case sdaiSELECT:
+                return select_value;
+            case sdaiAGGR:
+            case ARRAY_TYPE:
+            case BAG_TYPE:
+            case SET_TYPE:
+            case LIST_TYPE:
+                return aggregate_value;
+            default:
+                return 0;
+        }
+    }
+};
+
 /**********
    (member) functions for the select class SDAI_Select
 **********/
 SDAI_Select::SDAI_Select( const SelectTypeDescriptor * s,
                          const TypeDescriptor * td )
-    : _type( s ), underlying_type( td ) {
+    : _storage( 0 ), _type( s ), underlying_type( td ),
+      base_type( td ? td->NonRefType() : UNKNOWN_TYPE ) {
 #ifdef SC_LOGGING
    *logStream << "Exiting SDAI_Select constructor." << endl;
 #endif
 }

-SDAI_Select::SDAI_Select( const SDAI_Select & other ) {
-    underlying_type = other.underlying_type;
-    base_type = other.base_type;
-    _type = other._type;
+SDAI_Select::SDAI_Select( const SDAI_Select & other )
+    : _storage( 0 ), _type( other._type ),
+      underlying_type( other.underlying_type ), base_type( other.base_type ),
+      val( other.val ), _error( other._error ) {
+    if( other._storage ) {
+        _storage = new Storage;
+        _storage->CopyFrom( *other._storage );
+    }
 #ifdef SC_LOGGING
    *logStream << "Exiting SDAI_Select constructor." << endl;
 #endif
 }

 SDAI_Select::~SDAI_Select() {
+    delete _storage;
 }

 SDAI_Select & SDAI_Select::operator=( const SDAI_Select & other ) {
@@ -52,10 +237,36 @@ SDAI_Select & SDAI_Select::operator=( const SDAI_Select & other ) {
        base_type = other.base_type;
        underlying_type = other.underlying_type;
        val = other.val;
+        if( other._storage ) {
+            if( !_storage ) {
+                _storage = new Storage;
+            }
+            _storage->CopyFrom( *other._storage );
+        } else {
+            delete _storage;
+            _storage = 0;
+        }
    }
    return *this;
 }

+SDAI_Select & SDAI_Select::operator=( const SDAI_Select * other ) {
+    if( other ) {
+        return operator=( *other );
+    }
+    nullify();
+    return *this;
+}
+
+SDAI_Select * SDAI_Select::Clone() const {
+    SDAI_Select * result = _type ? _type->CreateSelect() : 0;
+    if( !result ) {
+        result = new SDAI_Select( _type );
+    }
+    *result = *this;
+    return result;
+}
+
 Severity SDAI_Select::severity() const {
    return _error.severity();
 }
@@ -137,21 +348,265 @@ const TypeDescriptor  * SDAI_Select::CurrentUnderlyingType() const {
 const TypeDescriptor *
 SDAI_Select::SetUnderlyingType( const TypeDescriptor * td ) {
    //  don\'t do anything if the descriptor is bad
-    if( !td || !( _type -> CanBe( td ) ) ) {
+    if( !td || ( _type && !( _type -> CanBe( td ) ) ) ) {
        return 0;
    }

+    if( _storage && _storage->type != td ) {
+        _storage->Clear();
+    }
    base_type = td -> NonRefType();

    return underlying_type = td;
 }

+void * SDAI_Select::ValueAddress() {
+    if( !underlying_type ) {
+        return 0;
+    }
+    if( !_storage ) {
+        _storage = new Storage;
+    }
+    if( _storage->type != underlying_type && !_storage->Reset( underlying_type ) ) {
+        Error( "Unable to create storage for SELECT value." );
+        severity( SEVERITY_BUG );
+        return 0;
+    }
+    return _storage->Address();
+}
+
+const void * SDAI_Select::ValueAddress() const {
+    return const_cast<SDAI_Select *>( this )->ValueAddress();
+}
+
+SDAI_Select * SDAI_Select::NewSelect() {
+    SDAI_Select * result = _type ? _type->CreateSelect() : 0;
+    return result ? result : new SDAI_Select( _type );
+}
+
+const TypeDescriptor *
+SDAI_Select::AssignEntity( SDAI_Application_instance * se ) {
+    if( !_type || !se ) {
+        return 0;
+    }
+
+    TypeDescItr elements( _type->GetElements() );
+    const TypeDescriptor * td;
+    while( ( td = elements.NextTypeDesc() ) ) {
+        const EntityDescriptor * entity_type =
+            dynamic_cast<const EntityDescriptor *>( td->NonRefTypeDescriptor() );
+        if( entity_type && se->IsA( entity_type ) ) {
+            SetUnderlyingType( td );
+            if( !_storage ) {
+                _storage = new Storage;
+            }
+            if( !_storage->Reset( td ) ) {
+                return 0;
+            }
+            _storage->entity_value = se;
+            return td;
+        }
+        if( td->NonRefType() == sdaiSELECT && td->CanBe( se->eDesc ) ) {
+            SetUnderlyingType( td );
+            SDAI_Select * nested = static_cast<SDAI_Select *>( ValueAddress() );
+            if( nested && nested->AssignEntity( se ) ) {
+                return td;
+            }
+        }
+    }
+
+    severity( SEVERITY_WARNING );
+    Error( "Mismatch in underlying type." );
+    return 0;
+}
+
+BASE_TYPE SDAI_Select::ValueType() const {
+    if( !underlying_type ) {
+        return UNKNOWN_TYPE;
+    }
+    if( underlying_type->NonRefType() == sdaiSELECT ) {
+        const SDAI_Select * nested =
+            static_cast<const SDAI_Select *>( ValueAddress() );
+        return nested ? nested->ValueType() : UNKNOWN_TYPE;
+    }
+    return underlying_type->NonRefType();
+}
+
+bool SDAI_Select::SetInteger( const TypeDescriptor * td, SDAI_Integer value ) {
+    if( !td || td->NonRefType() != sdaiINTEGER || !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_Integer * target = static_cast<SDAI_Integer *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetReal( const TypeDescriptor * td, SDAI_Real value ) {
+    if( !td || ( td->NonRefType() != sdaiREAL && td->NonRefType() != sdaiNUMBER ) ||
+            !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_Real * target = static_cast<SDAI_Real *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetString( const TypeDescriptor * td, const SDAI_String & value ) {
+    if( !td || td->NonRefType() != sdaiSTRING || !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_String * target = static_cast<SDAI_String *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetBinary( const TypeDescriptor * td, const SDAI_Binary & value ) {
+    if( !td || td->NonRefType() != sdaiBINARY || !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_Binary * target = static_cast<SDAI_Binary *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetEnum( const TypeDescriptor * td, const SDAI_Enum & value ) {
+    PrimitiveType kind = td ? td->NonRefType() : UNKNOWN_TYPE;
+    if( !td || ( kind != sdaiENUMERATION && kind != sdaiBOOLEAN && kind != sdaiLOGICAL ) ||
+            !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_Enum * target = static_cast<SDAI_Enum *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetSelect( const TypeDescriptor * td, const SDAI_Select & value ) {
+    if( !td || td->NonRefType() != sdaiSELECT || !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    SDAI_Select * target = static_cast<SDAI_Select *>( ValueAddress() );
+    if( target ) {
+        *target = value;
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetAggregate( const TypeDescriptor * td, const STEPaggregate & value ) {
+    if( !td || !td->IsAggrType() || !SetUnderlyingType( td ) ) {
+        return false;
+    }
+    STEPaggregate * target = static_cast<STEPaggregate *>( ValueAddress() );
+    if( target ) {
+        target->ShallowCopy( value );
+    }
+    return target != 0;
+}
+
+bool SDAI_Select::SetEntity( SDAI_Application_instance * value ) {
+    return AssignEntity( value ) != 0;
+}
+
+SDAI_Integer * SDAI_Select::IntegerValue() {
+    return underlying_type && underlying_type->NonRefType() == sdaiINTEGER ?
+        static_cast<SDAI_Integer *>( ValueAddress() ) : 0;
+}
+
+const SDAI_Integer * SDAI_Select::IntegerValue() const {
+    return underlying_type && underlying_type->NonRefType() == sdaiINTEGER ?
+        static_cast<const SDAI_Integer *>( ValueAddress() ) : 0;
+}
+
+SDAI_Real * SDAI_Select::RealValue() {
+    BASE_TYPE kind = underlying_type ? underlying_type->NonRefType() : UNKNOWN_TYPE;
+    return ( kind == sdaiREAL || kind == sdaiNUMBER ) ?
+        static_cast<SDAI_Real *>( ValueAddress() ) : 0;
+}
+
+const SDAI_Real * SDAI_Select::RealValue() const {
+    BASE_TYPE kind = underlying_type ? underlying_type->NonRefType() : UNKNOWN_TYPE;
+    return ( kind == sdaiREAL || kind == sdaiNUMBER ) ?
+        static_cast<const SDAI_Real *>( ValueAddress() ) : 0;
+}
+
+SDAI_String * SDAI_Select::StringValue() {
+    return underlying_type && underlying_type->NonRefType() == sdaiSTRING ?
+        static_cast<SDAI_String *>( ValueAddress() ) : 0;
+}
+
+const SDAI_String * SDAI_Select::StringValue() const {
+    return underlying_type && underlying_type->NonRefType() == sdaiSTRING ?
+        static_cast<const SDAI_String *>( ValueAddress() ) : 0;
+}
+
+SDAI_Binary * SDAI_Select::BinaryValue() {
+    return underlying_type && underlying_type->NonRefType() == sdaiBINARY ?
+        static_cast<SDAI_Binary *>( ValueAddress() ) : 0;
+}
+
+const SDAI_Binary * SDAI_Select::BinaryValue() const {
+    return underlying_type && underlying_type->NonRefType() == sdaiBINARY ?
+        static_cast<const SDAI_Binary *>( ValueAddress() ) : 0;
+}
+
+SDAI_Enum * SDAI_Select::EnumValue() {
+    BASE_TYPE kind = underlying_type ? underlying_type->NonRefType() : UNKNOWN_TYPE;
+    return ( kind == sdaiENUMERATION || kind == sdaiBOOLEAN || kind == sdaiLOGICAL ) ?
+        static_cast<SDAI_Enum *>( ValueAddress() ) : 0;
+}
+
+const SDAI_Enum * SDAI_Select::EnumValue() const {
+    BASE_TYPE kind = underlying_type ? underlying_type->NonRefType() : UNKNOWN_TYPE;
+    return ( kind == sdaiENUMERATION || kind == sdaiBOOLEAN || kind == sdaiLOGICAL ) ?
+        static_cast<const SDAI_Enum *>( ValueAddress() ) : 0;
+}
+
+SDAI_Select * SDAI_Select::SelectValue() {
+    return underlying_type && underlying_type->NonRefType() == sdaiSELECT ?
+        static_cast<SDAI_Select *>( ValueAddress() ) : 0;
+}
+
+const SDAI_Select * SDAI_Select::SelectValue() const {
+    return underlying_type && underlying_type->NonRefType() == sdaiSELECT ?
+        static_cast<const SDAI_Select *>( ValueAddress() ) : 0;
+}
+
+STEPaggregate * SDAI_Select::AggregateValue() {
+    return underlying_type && underlying_type->IsAggrType() ?
+        static_cast<STEPaggregate *>( ValueAddress() ) : 0;
+}
+
+const STEPaggregate * SDAI_Select::AggregateValue() const {
+    return underlying_type && underlying_type->IsAggrType() ?
+        static_cast<const STEPaggregate *>( ValueAddress() ) : 0;
+}
+
+SDAI_Application_instance * SDAI_Select::EntityValue() const {
+    if( !_storage || !underlying_type || underlying_type->NonRefType() != sdaiINSTANCE ) {
+        return 0;
+    }
+    return _storage->entity_value;
+}
+
 bool SDAI_Select::exists() const {
    return underlying_type != NULL;
 }

 void SDAI_Select::nullify() {
    underlying_type = 0;
+    base_type = UNKNOWN_TYPE;
+    if( _storage ) {
+        _storage->Clear();
+    }
 }

 Severity SDAI_Select::SelectValidLevel( const char * attrValue, ErrorDescriptor * err,
@@ -165,6 +620,155 @@ Severity SDAI_Select::SelectValidLevel( const char * attrValue, ErrorDescriptor
    return s;
 }

+void SDAI_Select::STEPwrite_content( ostream & out, const char * currSch ) const {
+    const void * value = ValueAddress();
+    if( !underlying_type || !value ) {
+        out << "$";
+        return;
+    }
+
+    switch( underlying_type->NonRefType() ) {
+        case sdaiINTEGER:
+            out << *static_cast<const SDAI_Integer *>( value );
+            break;
+        case sdaiREAL:
+        case sdaiNUMBER:
+            WriteReal( *static_cast<const SDAI_Real *>( value ), out );
+            break;
+        case sdaiINSTANCE:
+            static_cast<SDAI_Application_instance *>(
+                const_cast<void *>( value ) )->STEPwrite_reference( out );
+            break;
+        case sdaiSTRING:
+            static_cast<const SDAI_String *>( value )->STEPwrite( out );
+            break;
+        case sdaiBINARY:
+            static_cast<const SDAI_Binary *>( value )->STEPwrite( out );
+            break;
+        case sdaiBOOLEAN:
+        case sdaiLOGICAL:
+        case sdaiENUMERATION:
+            static_cast<const SDAI_Enum *>( value )->STEPwrite( out );
+            break;
+        case sdaiSELECT:
+            static_cast<const SDAI_Select *>( value )->STEPwrite( out, currSch );
+            break;
+        case sdaiAGGR:
+        case ARRAY_TYPE:
+        case BAG_TYPE:
+        case SET_TYPE:
+        case LIST_TYPE:
+            static_cast<const STEPaggregate *>( value )->STEPwrite( out, currSch );
+            break;
+        default:
+            out << "$";
+            break;
+    }
+}
+
+Severity SDAI_Select::STEPread_content( istream & in, InstMgrBase * instances,
+                                        const char * utype, int addFileId,
+                                        const char * currSch ) {
+    if( !underlying_type ) {
+        severity( SEVERITY_BUG );
+        Error( "Unable to create storage for SELECT value." );
+        return severity();
+    }
+
+    void * value = ValueAddress();
+    if( underlying_type->NonRefType() != sdaiINSTANCE && !value ) {
+        severity( SEVERITY_BUG );
+        Error( "Unable to create storage for SELECT value." );
+        return severity();
+    }
+
+    switch( underlying_type->NonRefType() ) {
+        case sdaiINTEGER:
+            ReadInteger( *static_cast<SDAI_Integer *>( value ), in, &_error, ")," );
+            break;
+        case sdaiREAL:
+        case sdaiNUMBER:
+            ReadReal( *static_cast<SDAI_Real *>( value ), in, &_error, ")," );
+            break;
+        case sdaiINSTANCE: {
+            SDAI_Application_instance * entity =
+                ReadEntityRef( in, &_error, ",)", instances, addFileId );
+            if( entity && entity != S_ENTITY_NULL && underlying_type->CanBe( entity->eDesc ) ) {
+                _storage->entity_value = entity;
+            } else {
+                Error( "Reference to instance that is not indicated type\n" );
+                nullify();
+                return severity( SEVERITY_USERMSG );
+            }
+            break;
+        }
+        case sdaiSTRING:
+            static_cast<SDAI_String *>( value )->STEPread( in, &_error );
+            break;
+        case sdaiBINARY:
+            static_cast<SDAI_Binary *>( value )->STEPread( in, &_error );
+            break;
+        case sdaiBOOLEAN:
+        case sdaiLOGICAL:
+        case sdaiENUMERATION:
+            static_cast<SDAI_Enum *>( value )->STEPread( in, &_error );
+            break;
+        case sdaiSELECT:
+            static_cast<SDAI_Select *>( value )->STEPread(
+                in, &_error, instances, utype, addFileId, currSch );
+            break;
+        case sdaiAGGR:
+        case ARRAY_TYPE:
+        case BAG_TYPE:
+        case SET_TYPE:
+        case LIST_TYPE:
+            static_cast<STEPaggregate *>( value )->STEPread(
+                in, &_error, underlying_type->AggrElemTypeDescriptor(),
+                instances, addFileId, currSch );
+            break;
+        default:
+            severity( SEVERITY_WARNING );
+            Error( "Mismatch in underlying type." );
+            break;
+    }
+    return severity();
+}
+
+Severity SDAI_Select::StrToVal_content( const char * str, InstMgrBase * instances ) {
+    if( !underlying_type ) {
+        return severity( SEVERITY_BUG );
+    }
+    void * value = ValueAddress();
+    if( underlying_type->NonRefType() != sdaiINSTANCE && !value ) {
+        return severity( SEVERITY_BUG );
+    }
+
+    switch( underlying_type->NonRefType() ) {
+        case sdaiSTRING:
+            return static_cast<SDAI_String *>( value )->StrToVal( str );
+        case sdaiBINARY:
+            return static_cast<SDAI_Binary *>( value )->StrToVal( str, &_error );
+        case sdaiBOOLEAN:
+        case sdaiLOGICAL:
+        case sdaiENUMERATION:
+            return static_cast<SDAI_Enum *>( value )->StrToVal( str, &_error );
+        case sdaiSELECT:
+            return static_cast<SDAI_Select *>( value )->StrToVal(
+                str, underlying_type->Name(), &_error, instances );
+        case sdaiAGGR:
+        case ARRAY_TYPE:
+        case BAG_TYPE:
+        case SET_TYPE:
+        case LIST_TYPE:
+            return static_cast<STEPaggregate *>( value )->StrToVal(
+                str, &_error, underlying_type->AggrElemTypeDescriptor(), instances );
+        default: {
+            istringstream input( str );
+            return STEPread_content( input, instances );
+        }
+    }
+}
+
 Severity SDAI_Select::StrToVal( const char * Val, const char * selectType,
                                ErrorDescriptor * err, InstMgrBase * instances ) {
    severity( SEVERITY_NULL );
@@ -580,7 +1184,7 @@ void SDAI_Select::STEPwrite( ostream & out, const char * currSch )  const {
 void SDAI_Select::STEPwrite_verbose( ostream & out, const char * currSch ) const {
    std::string tmp;
    out << StrToUpper( CurrentUnderlyingType()->Name( currSch ), tmp ) << "(";
-    STEPwrite_content( out );
+    STEPwrite_content( out, currSch );
    out << ")";
 }

@@ -1,14 +1,15 @@
 #include "clstepcore/selectTypeDescriptor.h"
+#include "clstepcore/sdaiSelect.h"

 ///////////////////////////////////////////////////////////////////////////////
 // SelectTypeDescriptor functions
 ///////////////////////////////////////////////////////////////////////////////

-SDAI_Select * SelectTypeDescriptor::CreateSelect() {
+SDAI_Select * SelectTypeDescriptor::CreateSelect() const {
    if( CreateNewSelect ) {
        return CreateNewSelect();
    } else {
-        return 0;
+        return new SDAI_Select( this );
    }
 }

@@ -23,7 +23,9 @@ endfunction(add_stepcore_test name libs)
 add_stepcore_test("SupertypesIterator" "stepcore;steputils;stepeditor;stepdai") #all these libs are necessary?
 add_stepcore_test("operators_STEPattribute" "stepcore;steputils;stepeditor;stepdai")
 add_stepcore_test("operators_SDAI_Select" "stepcore;steputils;stepeditor;stepdai")
+add_stepcore_test("descriptor_SDAI_Select" "stepcore;steputils;stepeditor;stepdai")
 add_stepcore_test("null_attr" "stepcore;steputils;stepeditor;stepdai")
+add_stepcore_test("late_bound_entity" "stepcore;steputils;stepeditor;stepdai")

 # Local Variables:
 # tab-width: 8
@@ -0,0 +1,81 @@
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+#include <string>
+
+#include "clstepcore/ExpDict.h"
+#include "clstepcore/sdaiSelect.h"
+
+static bool expect( bool condition, const char * message ) {
+    if( !condition ) {
+        std::cerr << message << std::endl;
+    }
+    return condition;
+}
+
+int main() {
+    TypeDescriptor integer_type( "integer_choice", sdaiINTEGER, 0, "INTEGER" );
+    TypeDescriptor string_type( "string_choice", sdaiSTRING, 0, "STRING" );
+    SelectTypeDescriptor choice_type(
+        ~( sdaiINTEGER | sdaiSTRING ), "choice", sdaiSELECT, 0,
+        "SELECT (integer_choice, string_choice)" );
+    choice_type.Elements().AddNode( &integer_type );
+    choice_type.Elements().AddNode( &string_type );
+
+    bool pass = true;
+    SDAI_Select value( &choice_type );
+    pass &= expect( value.SetInteger( &integer_type, 42 ),
+                    "descriptor SELECT rejected an integer choice" );
+    pass &= expect( value.IntegerValue() && *value.IntegerValue() == 42,
+                    "descriptor SELECT did not retain its integer value" );
+
+    std::ostringstream integer_output;
+    value.STEPwrite_content( integer_output );
+    pass &= expect( integer_output.str() == "42",
+                    "descriptor SELECT wrote an incorrect integer" );
+
+    SDAI_Select copy( value );
+    pass &= expect( copy.IntegerValue() && *copy.IntegerValue() == 42,
+                    "descriptor SELECT copy lost its integer value" );
+
+    ErrorDescriptor error;
+    pass &= expect( value.StrToVal( "17", "integer_choice", &error ) == SEVERITY_NULL,
+                    "descriptor SELECT could not parse an integer" );
+    pass &= expect( value.IntegerValue() && *value.IntegerValue() == 17,
+                    "descriptor SELECT parsed the wrong integer" );
+
+    SDAI_String text( "descriptor driven" );
+    pass &= expect( value.SetString( &string_type, text ),
+                    "descriptor SELECT rejected a string choice" );
+    pass &= expect( value.StringValue() &&
+                    std::string( value.StringValue()->c_str() ) == "descriptor driven",
+                    "descriptor SELECT did not retain its string value" );
+
+    std::ostringstream string_output;
+    value.STEPwrite_content( string_output );
+    pass &= expect( string_output.str() == "descriptor driven",
+                    "descriptor SELECT wrote an incorrect string" );
+
+    EntityDescriptor entity_type( "entity_choice", 0, LFalse, LFalse );
+    SelectTypeDescriptor entity_choice_type(
+        ~sdaiINSTANCE, "entity_choice_select", sdaiSELECT, 0,
+        "SELECT (entity_choice)" );
+    entity_choice_type.Elements().AddNode( &entity_type );
+    SDAI_Application_instance entity( 99 );
+    entity.eDesc = &entity_type;
+    SDAI_Select entity_value( &entity_choice_type );
+    pass &= expect( entity_value.SetEntity( &entity ),
+                    "descriptor SELECT rejected an entity choice" );
+    pass &= expect( entity_value.EntityValue() == &entity,
+                    "descriptor SELECT did not retain its entity value" );
+
+    std::ostringstream entity_output;
+    entity_value.STEPwrite_content( entity_output );
+    pass &= expect( entity_output.str() == "#99",
+                    "descriptor SELECT wrote an incorrect entity reference" );
+
+    value.set_null();
+    pass &= expect( value.is_null(), "descriptor SELECT did not clear its value" );
+
+    return pass ? EXIT_SUCCESS : EXIT_FAILURE;
+}
@@ -0,0 +1,331 @@
+#include "clstepcore/Registry.h"
+#include "clstepcore/STEPaggrInt.h"
+#include "clstepcore/STEPattribute.h"
+#include "clstepcore/derivedAttribute.h"
+#include "clstepcore/complexSupport.h"
+#include "clstepcore/schemaInit.h"
+#include "clstepcore/schemaModule.h"
+#include "clstepcore/sdaiSelect.h"
+
+#include <string>
+
+namespace {
+
+Schema * testSchema = 0;
+EntityDescriptor * baseEntity = 0;
+EntityDescriptor * leafEntity = 0;
+AttrDescriptor * labelAttribute = 0;
+AttrDescriptor * lengthAttribute = 0;
+Derived_attribute * derivedLabel = 0;
+AttrDescriptor * redefinedLabel = 0;
+TypeDescriptor * labelType = 0;
+TypeDescriptor * distanceType = 0;
+
+Schema * packedSchema = 0;
+SchemaModule packedSchemaModule;
+SchemaLoadResult packedSchemaResult = { SchemaLoad_Ok, 0 };
+
+struct PackedTestSchemaImage {
+    SchemaModuleImage header;
+    SchemaImageSchemaRecord schemas[1];
+    SchemaImageEntityRecord entities[1];
+    SchemaImageTypeRecord types[1];
+    SchemaImageAttributeRecord attributes[1];
+    SchemaImageRenameRecord renames[1];
+    char strings[39];
+};
+
+const PackedTestSchemaImage packedTestSchemaImage = {
+    { SchemaModuleImageVersion_2, 1, 1, 1,
+      sizeof( PackedTestSchemaImage ), SchemaModuleImage_FullMetadata, 1, 38,
+      offsetof( PackedTestSchemaImage, schemas ),
+      offsetof( PackedTestSchemaImage, entities ),
+      offsetof( PackedTestSchemaImage, types ),
+      offsetof( PackedTestSchemaImage, attributes ),
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      offsetof( PackedTestSchemaImage, strings ), 0, 1234,
+      1, offsetof( PackedTestSchemaImage, renames ) },
+    { { 1, 0, 1, 0, 1 } },
+    { { 0, 8, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0 } },
+    { { 0, 20, 27, sdaiREAL, TypeDescriptorInit_Base, 0,
+        { SchemaImageRef_Builtin, 0, sdaiREAL }, UINT32_MAX,
+        0, 0, 0, 0, 0, 0 } },
+    { { 14, { SchemaImageRef_Type, 0, 0 },
+        0, 0, AttrType_Explicit, 0, 0, 0 } },
+    { { { SchemaImageRef_Entity, 0, 0 }, 0, 32 } },
+    "\000Packed\000Thing\000value\000Length\000REAL\000Alias\000"
+};
+
+void initializePackedSchema( Registry & registry ) {
+    const SchemaImageSchemaBinding schemas[] = {
+        { &packedSchema, 0, &packedSchemaModule }
+    };
+    SchemaLoadContext context;
+    packedSchemaResult = InitializeSchemaFromImage(
+        registry, packedTestSchemaImage.header, schemas, 1, 0, 0, context );
+}
+
+void initializeLateSchema( Registry & registry ) {
+    const SchemaInitRecord schemas[] = {
+        { &testSchema, "Late_Bound_Test", 0 }
+    };
+    InitializeSchemas( registry, schemas, 1 );
+    InitializeSchemaModuleImages( schemas, 1 );
+
+    const EntityDescriptorInitRecord entities[] = {
+        { &baseEntity, "Base", &testSchema, LFalse, LFalse, 0 },
+        { &leafEntity, "Leaf", &testSchema, LFalse, LFalse, 0 }
+    };
+    InitializeEntityDescriptors( entities, 2 );
+
+    const TypeDescriptorInitRecord types[] = {
+        TypeDescriptorInitRecord( &labelType, "Label_Type", STRING_TYPE,
+                                  &testSchema, "STRING" ),
+        TypeDescriptorInitRecord( &distanceType, "Distance_Type", REAL_TYPE,
+                                  &testSchema, "REAL" )
+    };
+    InitializeTypeDescriptors( types, 2 );
+    InitializeTypeMetadata( registry, *testSchema, *distanceType, t_sdaiREAL,
+                            0, 0 );
+    InitializeTypeMetadata( registry, *testSchema, *labelType, t_sdaiSTRING,
+                            0, 0 );
+
+    const AttributeInitRecord baseAttributes[] = {
+        AttributeInitRecord( &labelAttribute, "label", t_sdaiSTRING,
+                             LFalse, LFalse, AttrType_Explicit )
+    };
+    InitializeEntityMetadata( registry, *baseEntity, *testSchema, 0, 0,
+                              baseAttributes, 1 );
+
+    const EntitySupertypeInitRecord supertypes[] = { { baseEntity } };
+    const AttributeInitRecord leafAttributes[] = {
+        AttributeInitRecord( &lengthAttribute, "length", t_sdaiREAL,
+                             LFalse, LFalse, AttrType_Explicit ),
+        AttributeInitRecord( &derivedLabel, "base.label", t_sdaiSTRING,
+                             LFalse, LFalse, AttrType_Deriving, "'derived'" )
+    };
+    InitializeEntityMetadata( registry, *leafEntity, *testSchema,
+                              supertypes, 1, leafAttributes, 2 );
+}
+
+}
+
+int main() {
+#define CHECK(condition) do { if( !( condition ) ) return __LINE__; } while( 0 )
+    Registry registry( initializeLateSchema );
+    const EntityDescriptor * entities[] = { baseEntity, leafEntity };
+    const TypeDescriptor * types[] = { t_sdaiSTRING, t_sdaiREAL };
+    const AttrDescriptor * attributes[] = {
+        labelAttribute, lengthAttribute, derivedLabel
+    };
+    SchemaModule module;
+    module.Initialize( *testSchema, entities, 2, types, 2, attributes, 3 );
+    CHECK( module.IsInitialized() );
+    CHECK( &module.GetSchema() == testSchema );
+    CHECK( module.EntityCount() == 2 && module.Entity( 1 ) == leafEntity );
+    CHECK( module.TypeCount() == 2 && module.Type( 0 ) == t_sdaiSTRING );
+    CHECK( module.AttributeCount() == 3 &&
+           module.Attribute( 2 ) == derivedLabel );
+    CHECK( module.Entity( 2 ) == 0 && module.Type( 2 ) == 0 &&
+           module.Attribute( 3 ) == 0 );
+
+    const SchemaModuleImage image = {
+        SchemaModuleImageVersion_1, 2, 2, 3,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0
+    };
+    SchemaModule packedModule;
+    packedModule.InitializeFromImage( *testSchema, image );
+    CHECK( packedModule.EntityCount() == 2 );
+    CHECK( packedModule.Entity( 0 ) == baseEntity );
+    CHECK( packedModule.Entity( 1 ) == leafEntity );
+    CHECK( packedModule.TypeCount() == 2 );
+    CHECK( packedModule.Type( 0 ) == labelType );
+    CHECK( packedModule.Type( 1 ) == distanceType );
+    CHECK( packedModule.AttributeCount() == 3 );
+    CHECK( packedModule.Attribute( 0 ) == labelAttribute );
+    CHECK( packedModule.Attribute( 1 ) == lengthAttribute );
+    CHECK( packedModule.Attribute( 2 ) == derivedLabel );
+
+    Registry packedRegistry( initializePackedSchema );
+    CHECK( packedSchemaResult.Succeeded() );
+    CHECK( packedSchemaModule.IsInitialized() );
+    CHECK( packedSchemaModule.Fingerprint() == 1234 );
+    CHECK( packedSchemaModule.EntityCount() == 1 );
+    CHECK( packedSchemaModule.Entity( 0 )->Name() == std::string( "Thing" ) );
+    CHECK( packedSchemaModule.TypeCount() == 1 );
+    CHECK( packedSchemaModule.AttributeCount() == 1 );
+    CHECK( std::string(
+               packedSchemaModule.Entity( 0 )->Name( "Packed" ) ) ==
+           "Alias" );
+    SDAI_Application_instance * packedInstance =
+        packedRegistry.ObjCreate( "Thing" );
+    CHECK( packedInstance != 0 );
+    delete packedInstance;
+
+    SchemaModuleImage invalidImage = packedTestSchemaImage.header;
+    invalidImage.byteSize = sizeof( SchemaModuleImage ) - 1;
+    const SchemaImageSchemaBinding invalidBindings[] = {
+        { &packedSchema, 0, &packedSchemaModule }
+    };
+    SchemaLoadContext invalidContext;
+    SchemaLoadResult invalidResult = InitializeSchemaFromImage(
+        packedRegistry, invalidImage, invalidBindings, 1, 0, 0,
+        invalidContext );
+    CHECK( invalidResult.error == SchemaLoad_TruncatedImage );
+
+    const size_t noNode = static_cast<size_t>( -1 );
+    const ComplexNodeInitRecord complexNodes[] = {
+        { ComplexNodeInit_And, 0, 1, noNode },
+        { ComplexNodeInit_Simple, "base", noNode, 2 },
+        { ComplexNodeInit_Or, 0, 3, noNode },
+        { ComplexNodeInit_Simple, "leaf", noNode, 4 },
+        { ComplexNodeInit_Simple, "other_leaf", noNode, noNode }
+    };
+    const ComplexListInitRecord complexLists[] = { { 0 } };
+    ComplexCollect * complex = InitializeComplexSupport(
+        complexNodes, 5, complexLists, 1 );
+    CHECK( complex && complex->clists && complex->clists->head );
+    CHECK( complex->clists->head->childCount() == 2 );
+    MultList * choice = dynamic_cast<MultList *>(
+        complex->clists->head->getChild( 1 ) );
+    CHECK( choice && choice->childCount() == 2 );
+    delete complex;
+
+    struct PackedTestComplexImage {
+        PackedComplexImage header;
+        PackedComplexNode nodes[5];
+        PackedComplexList lists[1];
+        char strings[23];
+    };
+    const PackedTestComplexImage packedComplexImage = {
+        { PackedComplexImageVersion_1, sizeof( PackedTestComplexImage ),
+          offsetof( PackedTestComplexImage, strings ), 22,
+          offsetof( PackedTestComplexImage, nodes ), 5,
+          offsetof( PackedTestComplexImage, lists ), 1 },
+        {
+            { ComplexNodeInit_And, 0, 1, UINT32_MAX },
+            { ComplexNodeInit_Simple, 1, UINT32_MAX, 2 },
+            { ComplexNodeInit_Or, 0, 3, UINT32_MAX },
+            { ComplexNodeInit_Simple, 6, UINT32_MAX, 4 },
+            { ComplexNodeInit_Simple, 11, UINT32_MAX, UINT32_MAX }
+        },
+        { { 0 } },
+        "\000base\000leaf\000other_leaf\000"
+    };
+    SchemaLoadResult complexResult = { SchemaLoad_Ok, 0 };
+    complex = InitializePackedComplexSupport(
+        packedComplexImage.header, &complexResult );
+    CHECK( complexResult.Succeeded() && complex );
+    CHECK( complex->clists->head->childCount() == 2 );
+    delete complex;
+
+    PackedTestComplexImage cyclicComplex = packedComplexImage;
+    cyclicComplex.nodes[4].nextSibling = 2;
+    complex = InitializePackedComplexSupport(
+        cyclicComplex.header, &complexResult );
+    CHECK( !complex && complexResult.error == SchemaLoad_InvalidReference );
+
+    EnumTypeDescriptor colorType(
+        "Color", sdaiENUMERATION, testSchema,
+        "ENUMERATION OF (RED, GREEN)", 0 );
+    const char * colorElements[] = { "RED", "GREEN" };
+    RegisterEnumDescriptorElements( colorType, colorElements, 2 );
+    SDAI_Enum * color = colorType.CreateEnum();
+    CHECK( color && color->no_elements() == 2 );
+    CHECK( std::string( color->get_value_at( 1 ) ) == "GREEN" );
+    CHECK( color->put( "RED" ) == 0 );
+    delete color;
+
+    SelectTypeDescriptor choiceType(
+        ~sdaiSTRING, "Choice", sdaiSELECT, testSchema, "SELECT (STRING)", 0 );
+    choiceType.Elements().AddNode(
+        const_cast<TypeDescriptor *>( t_sdaiSTRING ) );
+    SDAI_Select * genericChoice = choiceType.CreateSelect();
+    CHECK( genericChoice &&
+           genericChoice->SetString( t_sdaiSTRING, "generic" ) );
+    CHECK( genericChoice->StringValue() &&
+           *genericChoice->StringValue() == "generic" );
+    delete genericChoice;
+
+    ListTypeDescriptor integerList(
+        "Integer_List", LIST_TYPE, testSchema, "LIST OF INTEGER", 0 );
+    integerList.ReferentType(
+        const_cast<TypeDescriptor *>( t_sdaiINTEGER ) );
+    STEPaggregate * integers = integerList.CreateAggregate();
+    CHECK( dynamic_cast<IntAggregate *>( integers ) != 0 );
+    delete integers;
+
+    ListTypeDescriptor uninitializedList;
+    CHECK( uninitializedList.Bound1Type() == bound_unset );
+    CHECK( uninitializedList.Bound2Type() == bound_unset );
+    STEPaggregate * fallbackAggregate = uninitializedList.CreateAggregate();
+    CHECK( dynamic_cast<GenericAggregate *>( fallbackAggregate ) != 0 );
+    delete fallbackAggregate;
+
+    AggrTypeDescriptor boundedAggregate(
+        1, 4, LTrue, const_cast<TypeDescriptor *>( t_sdaiINTEGER ) );
+    CHECK( boundedAggregate.Bound1Type() == bound_constant );
+    CHECK( boundedAggregate.Bound2Type() == bound_constant );
+    CHECK( boundedAggregate.Bound1() == 1 );
+    CHECK( boundedAggregate.Bound2() == 4 );
+
+    SDAI_Application_instance * instance = registry.ObjCreate( "leaf" );
+    CHECK( instance );
+    CHECK( instance->eDesc == leafEntity );
+    CHECK( instance->AttributeCount() == 2 );
+
+    instance->ResetAttributes();
+    STEPattribute * label = instance->NextAttribute();
+    STEPattribute * length = instance->NextAttribute();
+    CHECK( label && length );
+    CHECK( label->IsDerived() );
+    CHECK( length->StrToVal( "12.5", 0, 0 ) > SEVERITY_INCOMPLETE );
+    CHECK( length->Real() && *length->Real() > 12.49 &&
+           *length->Real() < 12.51 );
+
+    SDAI_Application_instance * copy = instance->Replicate();
+    CHECK( copy );
+    CHECK( copy->AttributeCount() == 2 );
+    copy->ResetAttributes();
+    copy->NextAttribute();
+    STEPattribute * copiedLength = copy->NextAttribute();
+    CHECK( copiedLength && copiedLength->Real() );
+    CHECK( *copiedLength->Real() > 12.49 && *copiedLength->Real() < 12.51 );
+
+    delete copy;
+
+    AttrDescriptor entityAttribute(
+        "target", leafEntity, LFalse, LFalse, AttrType_Explicit,
+        *baseEntity );
+    SDAI_Application_instance * entitySlot = 0;
+    STEPattribute boundEntityAttribute( entityAttribute, &entitySlot );
+    boundEntityAttribute.Entity( instance );
+    CHECK( entitySlot == instance );
+
+    delete instance;
+
+    redefinedLabel = new AttrDescriptor(
+        "label", t_sdaiREAL, LFalse, LFalse, AttrType_Redefining,
+        *leafEntity );
+    leafEntity->AddExplicitAttr( redefinedLabel );
+    SDAI_Application_instance * narrowed = registry.ObjCreate( "leaf" );
+    CHECK( narrowed && narrowed->AttributeCount() == 3 );
+    narrowed->ResetAttributes();
+    label = narrowed->NextAttribute();
+    narrowed->NextAttribute();
+    STEPattribute * narrowedLabel = narrowed->NextAttribute();
+    CHECK( label && narrowedLabel );
+    CHECK( label->IsDerived() );
+    CHECK( label->RedefiningAttr() == narrowedLabel );
+    CHECK( label->String() == 0 );
+    CHECK( label->Real() == narrowedLabel->Real() );
+    SDAI_Real narrowedValue = 7.25;
+    label->Real( &narrowedValue );
+    CHECK( narrowedLabel->Real() &&
+           *narrowedLabel->Real() > 7.24 &&
+           *narrowedLabel->Real() < 7.26 );
+    delete narrowed;
+#undef CHECK
+    return 0;
+}
@@ -39,6 +39,35 @@ bool testEqu( const STEPattribute & a1, const STEPattribute & a2, bool invert, c
    return pass;
 }

+bool testRedefinedDerivedWrite( const AttrDescriptor & ad ) {
+    SDAI_Integer inherited_value = 123L;
+    SDAI_Integer narrowed_value = 456L;
+    STEPattribute inherited( ad, & inherited_value );
+    STEPattribute narrowed( ad, & narrowed_value );
+
+    // A redeclared explicit attribute occupies its inherited physical-file
+    // slot, which is also marked derived in the generated supertype class.
+    inherited.Derive();
+    inherited.RedefiningAttr( & narrowed );
+
+    bool pass = true;
+    std::string value;
+    inherited.asStr( value );
+    if( inherited.asStr() != "456" || value != "456" ) {
+        std::cerr << "redefined derived attribute asStr() failed" << std::endl;
+        pass = false;
+    }
+
+    std::ostringstream output;
+    inherited.STEPwrite( output );
+    if( output.str() != "456" ) {
+        std::cerr << "redefined derived attribute STEPwrite() failed" << std::endl;
+        pass = false;
+    }
+
+    return pass;
+}
+
 int main( int /*argc*/, char ** /*argv*/ ) {
    bool pass = true;
    EntityDescriptor ed( "ename", 0, LFalse, LFalse );
@@ -64,6 +93,7 @@ int main( int /*argc*/, char ** /*argv*/ ) {

    STEPattribute aii( adi, & s2int );
    pass &= testEqu( ai, aii, true, "ints !=" );
+    pass &= testRedefinedDerivedWrite( adi );

    if( pass ) {
        exit( EXIT_SUCCESS );
@@ -260,7 +260,7 @@ const char * DirObj::ValidDirectories( const char * path ) {
    static char buf[MAXPATHLEN + 1];
    strncpy(buf, path, MAXPATHLEN);
 #endif
-    int i = strlen( path );
+    int i = (int)strlen( path );

    while( !IsADirectory( RealPath( buf ) ) && i >= 0 ) {
        for( --i; buf[i] != '/' && i >= 0; --i ) {
--- a/Show More
+++ b/Show More