Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop)

* commit 'af21ce90d9465e805807f17da21f93e64e03492a': (46 commits)
  Changed to Unix line endings and chmod -x.
  Fix runtest case for data to stdout in tool
  Updated the parallel install docs.
  Eliminated the need for a separate script variable.
  Flipped swapped testing strings.
  Specify variable type. Remove unnecessary whitespace.
  Added test_vol_plugin.sh to the list of scripts to clean
  Fixed a CMake build issue (CMake still doesn't run the VOL plugin tests)
  Added more sub-tests to the VOL plugin test.
  Added a simple test for registration of VOL connector plugins. Autotools only for right now, but this will be fleshed out in future work.
  OHDR tests now accept h5_fileaccess() fapls. Formatting, informative comments, and minor renaming.
  Fix some CMake listings
  Add error checking to the minimized dset header size calculation. Update printf->HDprintf statements.
  Remove `#if 0` block of deprecated code.
  Fix mistake with H5E_BEGIN_TRY {...} H5E_END_TRY block containing ERROR-raising macros. Formatting tweaks.
  Added a helpful message to the flush script.
  Added a shell script so we can run the parallel flush test on OpenMPI.
  Add "compact" storage test to relative header size comparisons.
  Formatting adjustments.
  Formatting adjustments
  ...

55 files changed, 4331 insertions, 2079 deletions

diff --git a/MANIFEST b/MANIFEST
index 8783d84..cb006cc 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -974,7 +974,6 @@
 ./test/dtypes.c
 ./test/dtransform.c
 ./test/earray.c
-./test/echo_vol.c
 ./test/efc.c
 ./test/enc_dec_plist.c
 ./test/enc_dec_plist_cross_platform.c
@@ -1022,6 +1021,7 @@
 ./test/gen_deflate.c
 ./test/gen_file_image.c
 ./test/gen_filespace.c
+./test/gen_filters.c
 ./test/gen_mergemsg.c
 ./test/gen_new_array.c
 ./test/gen_new_fill.c
@@ -1065,6 +1065,8 @@
 ./test/noencoder.h5
 ./test/none.h5
 ./test/ntypes.c
+./test/null_vol_connector.c
+./test/null_vol_connector.h
 ./test/ohdr.c
 ./test/objcopy.c
 ./test/page_buffer.c
@@ -1105,12 +1107,15 @@
 ./test/testlinks_env.sh.in
 ./test/test_filenotclosed.sh.in
 ./test/test_filter_plugin.sh.in
+./test/test_filters_le.h5
+./test/test_filters_be.h5
 ./test/testflushrefresh.sh.in
 ./test/testframe.c
 ./test/testhdf5.c
 ./test/testhdf5.h
 ./test/testlibinfo.sh.in
 ./test/test_usecases.sh.in
+./test/test_vol_plugin.sh.in
 ./test/testmeta.c
 ./test/testswmr.sh.in
 ./test/testvdsswmr.sh.in
@@ -1152,16 +1157,14 @@
 ./test/use_common.c
 ./test/use_disable_mdc_flushes.c
 ./test/use.h
-./test/vfd.c
-./test/vol.c
-./test/test_filters_le.h5
-./test/test_filters_be.h5
-./test/gen_filters.c
 ./test/vds.c
 ./test/vds_swmr.h
 ./test/vds_swmr_gen.c
 ./test/vds_swmr_reader.c
 ./test/vds_swmr_writer.c
+./test/vfd.c
+./test/vol.c
+./test/vol_plugin.c
 
 ./test/testfiles/err_compat_1
 ./test/testfiles/err_compat_2
@@ -1292,6 +1295,7 @@
 ./testpar/t_span_tree.c
 ./testpar/t_init_term.c
 ./testpar/testpar.h
+./testpar/testpflush.sh.in
 ./testpar/testphdf5.c
 ./testpar/testphdf5.h
 
diff --git a/config/cmake/CTestScript.cmake b/config/cmake/CTestScript.cmake
index 0269ba8..0269ba8 100755..100644
--- a/config/cmake/CTestScript.cmake
+++ b/config/cmake/CTestScript.cmake
diff --git a/config/cmake/HDF5_Examples_options.cmake b/config/cmake/HDF5_Examples_options.cmake
index 386e99c..386e99c 100755..100644
--- a/config/cmake/HDF5_Examples_options.cmake
+++ b/config/cmake/HDF5_Examples_options.cmake
diff --git a/config/cmake/libh5cc.in b/config/cmake/libh5cc.in
index f462d56..f462d56 100755..100644
--- a/config/cmake/libh5cc.in
+++ b/config/cmake/libh5cc.in
diff --git a/config/cmake/libhdf5.pc.in b/config/cmake/libhdf5.pc.in
index 4a2ebaa..4a2ebaa 100755..100644
--- a/config/cmake/libhdf5.pc.in
+++ b/config/cmake/libhdf5.pc.in
diff --git a/config/cmake/scripts/CTestScript.cmake b/config/cmake/scripts/CTestScript.cmake
index f4dffb3..3c866ff 100755..100644
--- a/config/cmake/scripts/CTestScript.cmake
+++ b/config/cmake/scripts/CTestScript.cmake
@@ -9,261 +9,261 @@
 # If you do not have access to either file, you may request a copy from
 # help@hdfgroup.org.
 #
-cmake_minimum_required (VERSION 3.10)

-########################################################

-# This dashboard is maintained by The HDF Group

-# For any comments please contact cdashhelp@hdfgroup.org

-#

-########################################################

-# -----------------------------------------------------------

-# -- Get environment

-# -----------------------------------------------------------

-if (NOT SITE_OS_NAME)

-  ## machine name not provided - attempt to discover with uname

-  ## -- set hostname

-  ## --------------------------

-  find_program (HOSTNAME_CMD NAMES hostname)

-  exec_program (${HOSTNAME_CMD} ARGS OUTPUT_VARIABLE HOSTNAME)

-  set (CTEST_SITE  "${HOSTNAME}${CTEST_SITE_EXT}")

-  find_program (UNAME NAMES uname)

-  macro (getuname name flag)

-    exec_program ("${UNAME}" ARGS "${flag}" OUTPUT_VARIABLE "${name}")

-  endmacro ()

-

-  getuname (osname -s)

-  getuname (osrel  -r)

-  getuname (cpu    -m)

-  message (STATUS "Dashboard script uname output: ${osname}-${osrel}-${cpu}\n")

-

-  set (CTEST_BUILD_NAME  "${osname}-${osrel}-${cpu}")

-else ()

-  ## machine name provided

-  ## --------------------------

-  if (CMAKE_HOST_UNIX)

-    set (CTEST_BUILD_NAME "${SITE_OS_NAME}-${SITE_OS_VERSION}-${SITE_OS_BITS}-${SITE_COMPILER_NAME}-${SITE_COMPILER_VERSION}")

-  else ()

-    set (CTEST_BUILD_NAME "${SITE_OS_NAME}-${SITE_OS_VERSION}-${SITE_COMPILER_NAME}")

-  endif ()

-endif ()

+cmake_minimum_required (VERSION 3.10)
+########################################################
+# This dashboard is maintained by The HDF Group
+# For any comments please contact cdashhelp@hdfgroup.org
+#
+########################################################
+# -----------------------------------------------------------
+# -- Get environment
+# -----------------------------------------------------------
+if (NOT SITE_OS_NAME)
+  ## machine name not provided - attempt to discover with uname
+  ## -- set hostname
+  ## --------------------------
+  find_program (HOSTNAME_CMD NAMES hostname)
+  exec_program (${HOSTNAME_CMD} ARGS OUTPUT_VARIABLE HOSTNAME)
+  set (CTEST_SITE  "${HOSTNAME}${CTEST_SITE_EXT}")
+  find_program (UNAME NAMES uname)
+  macro (getuname name flag)
+    exec_program ("${UNAME}" ARGS "${flag}" OUTPUT_VARIABLE "${name}")
+  endmacro ()
+
+  getuname (osname -s)
+  getuname (osrel  -r)
+  getuname (cpu    -m)
+  message (STATUS "Dashboard script uname output: ${osname}-${osrel}-${cpu}\n")
+
+  set (CTEST_BUILD_NAME  "${osname}-${osrel}-${cpu}")
+else ()
+  ## machine name provided
+  ## --------------------------
+  if (CMAKE_HOST_UNIX)
+    set (CTEST_BUILD_NAME "${SITE_OS_NAME}-${SITE_OS_VERSION}-${SITE_OS_BITS}-${SITE_COMPILER_NAME}-${SITE_COMPILER_VERSION}")
+  else ()
+    set (CTEST_BUILD_NAME "${SITE_OS_NAME}-${SITE_OS_VERSION}-${SITE_COMPILER_NAME}")
+  endif ()
+endif ()
 if (SITE_BUILDNAME_SUFFIX)
   set (CTEST_BUILD_NAME  "${SITE_BUILDNAME_SUFFIX}-${CTEST_BUILD_NAME}")
 endif ()
 set (BUILD_OPTIONS "${ADD_BUILD_OPTIONS} -DSITE:STRING=${CTEST_SITE} -DBUILDNAME:STRING=${CTEST_BUILD_NAME}")
-

-#-----------------------------------------------------------------------------

-# MAC machines need special option

-#-----------------------------------------------------------------------------

-if (APPLE)

-  # Compiler choice

-  execute_process (COMMAND xcrun --find cc OUTPUT_VARIABLE XCODE_CC OUTPUT_STRIP_TRAILING_WHITESPACE)

-  execute_process (COMMAND xcrun --find c++ OUTPUT_VARIABLE XCODE_CXX OUTPUT_STRIP_TRAILING_WHITESPACE)

-  set (ENV{CC} "${XCODE_CC}")

-  set (ENV{CXX} "${XCODE_CXX}")

-

-  set (BUILD_OPTIONS "${BUILD_OPTIONS} -DCTEST_USE_LAUNCHERS:BOOL=ON -DCMAKE_BUILD_WITH_INSTALL_RPATH:BOOL=OFF")

-endif ()

-

-#-----------------------------------------------------------------------------

-set (NEED_REPOSITORY_CHECKOUT 0)

-set (CTEST_CMAKE_COMMAND "\"${CMAKE_COMMAND}\"")

-if (CTEST_USE_TAR_SOURCE)

-  ## Uncompress source if tar file provided

-  ## --------------------------

-  if (WIN32)

-    message (STATUS "extracting... [${CMAKE_EXECUTABLE_NAME} x ${CTEST_DASHBOARD_ROOT}\\${CTEST_USE_TAR_SOURCE}.zip]")

-    execute_process (COMMAND ${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}\\${CTEST_USE_TAR_SOURCE}.zip RESULT_VARIABLE rv)

-  else ()

-    message (STATUS "extracting... [${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE}.tar]")

-    execute_process (COMMAND ${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE}.tar RESULT_VARIABLE rv)

-  endif ()

-

-  if (NOT rv EQUAL 0)

-    message (STATUS "extracting... [error-(${rv}) clean up]")

-    file (REMOVE_RECURSE "${CTEST_SOURCE_DIRECTORY}")

-    message (FATAL_ERROR "error: extract of ${CTEST_USE_TAR_SOURCE} failed")

-  endif ()

-

-  file (RENAME ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE} ${CTEST_SOURCE_DIRECTORY})

-  set (LOCAL_SKIP_UPDATE "TRUE")

-else ()

-  if (LOCAL_UPDATE)

-    if (CTEST_USE_GIT_SOURCE)

-      find_program (CTEST_GIT_COMMAND NAMES git git.cmd)

-      set (CTEST_GIT_UPDATE_OPTIONS)

-

-      if (NOT EXISTS "${CTEST_SOURCE_DIRECTORY}")

-        set (NEED_REPOSITORY_CHECKOUT 1)

-      endif ()

-

-      if (${NEED_REPOSITORY_CHECKOUT})

-        if (REPOSITORY_BRANCH)

-          set (CTEST_GIT_options "clone \"${REPOSITORY_URL}\" --branch  \"${REPOSITORY_BRANCH}\" --single-branch \"${CTEST_SOURCE_DIRECTORY}\" --recurse-submodules")

-        else ()

-          set (CTEST_GIT_options "clone \"${REPOSITORY_URL}\" \"${CTEST_SOURCE_DIRECTORY}\" --recurse-submodules")

-        endif ()

-        set (CTEST_CHECKOUT_COMMAND "${CTEST_GIT_COMMAND} ${CTEST_GIT_options}")

-      else ()

-        set (CTEST_GIT_options "pull")

-      endif ()

-      set (CTEST_UPDATE_COMMAND "${CTEST_GIT_COMMAND}")

-    else ()

-      ## --------------------------

-      ## use subversion to get source

-      #-----------------------------------------------------------------------------

-      ## cygwin does not handle the find_package() call

-      ## --------------------------

-      set (CTEST_UPDATE_COMMAND "SVNCommand")

-      if (NOT SITE_CYGWIN})

-        find_package (Subversion)

-        set (CTEST_SVN_COMMAND "${Subversion_SVN_EXECUTABLE}")

-        set (CTEST_UPDATE_COMMAND "${Subversion_SVN_EXECUTABLE}")

-      else ()

-        set (CTEST_SVN_COMMAND "/usr/bin/svn")

-        set (CTEST_UPDATE_COMMAND "/usr/bin/svn")

-      endif ()

-

-      if (NOT EXISTS "${CTEST_SOURCE_DIRECTORY}")

-        set (NEED_REPOSITORY_CHECKOUT 1)

-      endif ()

-

-      if (NOT CTEST_REPO_VERSION)

-        set (CTEST_REPO_VERSION "HEAD")

-      endif ()

-      if (${NEED_REPOSITORY_CHECKOUT})

-        set (CTEST_CHECKOUT_COMMAND

-            "\"${CTEST_SVN_COMMAND}\" co ${REPOSITORY_URL} \"${CTEST_SOURCE_DIRECTORY}\" -r ${CTEST_REPO_VERSION}")

-      else ()

-        if (CTEST_REPO_VERSION)

-          set (CTEST_SVN_UPDATE_OPTIONS "-r ${CTEST_REPO_VERSION}")

-        endif ()

-      endif ()

-    endif ()

-  endif ()

-endif ()

-

-#-----------------------------------------------------------------------------

-## Clear the build directory

-## --------------------------

-set (CTEST_START_WITH_EMPTY_BINARY_DIRECTORY TRUE)

-if (NOT EXISTS "${CTEST_BINARY_DIRECTORY}")

-  file (MAKE_DIRECTORY "${CTEST_BINARY_DIRECTORY}")

-else ()

-  ctest_empty_binary_directory (${CTEST_BINARY_DIRECTORY})

-endif ()

-

-# Use multiple CPU cores to build

-include (ProcessorCount)

-ProcessorCount (N)

+
+#-----------------------------------------------------------------------------
+# MAC machines need special option
+#-----------------------------------------------------------------------------
+if (APPLE)
+  # Compiler choice
+  execute_process (COMMAND xcrun --find cc OUTPUT_VARIABLE XCODE_CC OUTPUT_STRIP_TRAILING_WHITESPACE)
+  execute_process (COMMAND xcrun --find c++ OUTPUT_VARIABLE XCODE_CXX OUTPUT_STRIP_TRAILING_WHITESPACE)
+  set (ENV{CC} "${XCODE_CC}")
+  set (ENV{CXX} "${XCODE_CXX}")
+
+  set (BUILD_OPTIONS "${BUILD_OPTIONS} -DCTEST_USE_LAUNCHERS:BOOL=ON -DCMAKE_BUILD_WITH_INSTALL_RPATH:BOOL=OFF")
+endif ()
+
+#-----------------------------------------------------------------------------
+set (NEED_REPOSITORY_CHECKOUT 0)
+set (CTEST_CMAKE_COMMAND "\"${CMAKE_COMMAND}\"")
+if (CTEST_USE_TAR_SOURCE)
+  ## Uncompress source if tar file provided
+  ## --------------------------
+  if (WIN32)
+    message (STATUS "extracting... [${CMAKE_EXECUTABLE_NAME} x ${CTEST_DASHBOARD_ROOT}\\${CTEST_USE_TAR_SOURCE}.zip]")
+    execute_process (COMMAND ${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}\\${CTEST_USE_TAR_SOURCE}.zip RESULT_VARIABLE rv)
+  else ()
+    message (STATUS "extracting... [${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE}.tar]")
+    execute_process (COMMAND ${CMAKE_EXECUTABLE_NAME} -E tar -xvf ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE}.tar RESULT_VARIABLE rv)
+  endif ()
+
+  if (NOT rv EQUAL 0)
+    message (STATUS "extracting... [error-(${rv}) clean up]")
+    file (REMOVE_RECURSE "${CTEST_SOURCE_DIRECTORY}")
+    message (FATAL_ERROR "error: extract of ${CTEST_USE_TAR_SOURCE} failed")
+  endif ()
+
+  file (RENAME ${CTEST_DASHBOARD_ROOT}/${CTEST_USE_TAR_SOURCE} ${CTEST_SOURCE_DIRECTORY})
+  set (LOCAL_SKIP_UPDATE "TRUE")
+else ()
+  if (LOCAL_UPDATE)
+    if (CTEST_USE_GIT_SOURCE)
+      find_program (CTEST_GIT_COMMAND NAMES git git.cmd)
+      set (CTEST_GIT_UPDATE_OPTIONS)
+
+      if (NOT EXISTS "${CTEST_SOURCE_DIRECTORY}")
+        set (NEED_REPOSITORY_CHECKOUT 1)
+      endif ()
+
+      if (${NEED_REPOSITORY_CHECKOUT})
+        if (REPOSITORY_BRANCH)
+          set (CTEST_GIT_options "clone \"${REPOSITORY_URL}\" --branch  \"${REPOSITORY_BRANCH}\" --single-branch \"${CTEST_SOURCE_DIRECTORY}\" --recurse-submodules")
+        else ()
+          set (CTEST_GIT_options "clone \"${REPOSITORY_URL}\" \"${CTEST_SOURCE_DIRECTORY}\" --recurse-submodules")
+        endif ()
+        set (CTEST_CHECKOUT_COMMAND "${CTEST_GIT_COMMAND} ${CTEST_GIT_options}")
+      else ()
+        set (CTEST_GIT_options "pull")
+      endif ()
+      set (CTEST_UPDATE_COMMAND "${CTEST_GIT_COMMAND}")
+    else ()
+      ## --------------------------
+      ## use subversion to get source
+      #-----------------------------------------------------------------------------
+      ## cygwin does not handle the find_package() call
+      ## --------------------------
+      set (CTEST_UPDATE_COMMAND "SVNCommand")
+      if (NOT SITE_CYGWIN})
+        find_package (Subversion)
+        set (CTEST_SVN_COMMAND "${Subversion_SVN_EXECUTABLE}")
+        set (CTEST_UPDATE_COMMAND "${Subversion_SVN_EXECUTABLE}")
+      else ()
+        set (CTEST_SVN_COMMAND "/usr/bin/svn")
+        set (CTEST_UPDATE_COMMAND "/usr/bin/svn")
+      endif ()
+
+      if (NOT EXISTS "${CTEST_SOURCE_DIRECTORY}")
+        set (NEED_REPOSITORY_CHECKOUT 1)
+      endif ()
+
+      if (NOT CTEST_REPO_VERSION)
+        set (CTEST_REPO_VERSION "HEAD")
+      endif ()
+      if (${NEED_REPOSITORY_CHECKOUT})
+        set (CTEST_CHECKOUT_COMMAND
+            "\"${CTEST_SVN_COMMAND}\" co ${REPOSITORY_URL} \"${CTEST_SOURCE_DIRECTORY}\" -r ${CTEST_REPO_VERSION}")
+      else ()
+        if (CTEST_REPO_VERSION)
+          set (CTEST_SVN_UPDATE_OPTIONS "-r ${CTEST_REPO_VERSION}")
+        endif ()
+      endif ()
+    endif ()
+  endif ()
+endif ()
+
+#-----------------------------------------------------------------------------
+## Clear the build directory
+## --------------------------
+set (CTEST_START_WITH_EMPTY_BINARY_DIRECTORY TRUE)
+if (NOT EXISTS "${CTEST_BINARY_DIRECTORY}")
+  file (MAKE_DIRECTORY "${CTEST_BINARY_DIRECTORY}")
+else ()
+  ctest_empty_binary_directory (${CTEST_BINARY_DIRECTORY})
+endif ()
+
+# Use multiple CPU cores to build
+include (ProcessorCount)
+ProcessorCount (N)
 if (NOT N EQUAL 0)
   if (MAX_PROC_COUNT)
     if (N GREATER MAX_PROC_COUNT)
       set (N ${MAX_PROC_COUNT})
     endif ()
   endif ()
-  if (NOT WIN32)

-    set (CTEST_BUILD_FLAGS -j${N})

-  endif ()

-  set (ctest_test_args ${ctest_test_args} PARALLEL_LEVEL ${N})

-endif ()

-

-#-----------------------------------------------------------------------------

-# Send the main script as a note.

-list (APPEND CTEST_NOTES_FILES

-    "${CTEST_SCRIPT_DIRECTORY}/${CTEST_SCRIPT_NAME}"

-    "${CMAKE_CURRENT_LIST_FILE}"

-    "${CTEST_SOURCE_DIRECTORY}/config/cmake/cacheinit.cmake"

-)

-

-#-----------------------------------------------------------------------------

-# Check for required variables.

-# --------------------------

-foreach (req

-    CTEST_CMAKE_GENERATOR

-    CTEST_SITE

-    CTEST_BUILD_NAME

-  )

-  if (NOT DEFINED ${req})

-    message (FATAL_ERROR "The containing script must set ${req}")

-  endif ()

-endforeach ()

-

-#-----------------------------------------------------------------------------

-# Initialize the CTEST commands

-#------------------------------

-if (CMAKE_GENERATOR_TOOLSET)

-  set (CTEST_CONFIGURE_TOOLSET  "-T${CMAKE_GENERATOR_TOOLSET}")

-else ()

-  set (CTEST_CONFIGURE_TOOLSET  "")

-endif()

-if (LOCAL_MEMCHECK_TEST)

-  find_program (CTEST_MEMORYCHECK_COMMAND NAMES valgrind)

-  set (CTEST_CONFIGURE_COMMAND

-      "${CTEST_CMAKE_COMMAND} -C \"${CTEST_SOURCE_DIRECTORY}/config/cmake/mccacheinit.cmake\" -DCMAKE_BUILD_TYPE:STRING=${CTEST_CONFIGURATION_TYPE} ${BUILD_OPTIONS} \"-G${CTEST_CMAKE_GENERATOR}\" \"${CTEST_CONFIGURE_TOOLSET}\" \"${CTEST_SOURCE_DIRECTORY}\""

-  )

-else ()

-  if (LOCAL_COVERAGE_TEST)

-    find_program (CTEST_COVERAGE_COMMAND NAMES gcov)

-  endif ()

-  set (CTEST_CONFIGURE_COMMAND

-      "${CTEST_CMAKE_COMMAND} -C \"${CTEST_SOURCE_DIRECTORY}/config/cmake/cacheinit.cmake\" -DCMAKE_BUILD_TYPE:STRING=${CTEST_CONFIGURATION_TYPE} ${BUILD_OPTIONS} \"-G${CTEST_CMAKE_GENERATOR}\" \"${CTEST_CONFIGURE_TOOLSET}\" \"${CTEST_SOURCE_DIRECTORY}\""

-  )

-endif ()

-

-#-----------------------------------------------------------------------------

-## -- set output to english

-set ($ENV{LC_MESSAGES}  "en_EN")

-

-# Print summary information.

-foreach (v

-    CTEST_SITE

-    CTEST_BUILD_NAME

-    CTEST_SOURCE_DIRECTORY

-    CTEST_BINARY_DIRECTORY

-    CTEST_CMAKE_GENERATOR

-    CTEST_CONFIGURATION_TYPE

-    CTEST_GIT_COMMAND

-    CTEST_CHECKOUT_COMMAND

-    CTEST_CONFIGURE_COMMAND

-    CTEST_SCRIPT_DIRECTORY

-    CTEST_USE_LAUNCHERS

-  )

-  set (vars "${vars}  ${v}=[${${v}}]\n")

-endforeach ()

-message (STATUS "Dashboard script configuration:\n${vars}\n")

-

-#-----------------------------------------------------------------------------

-#-----------------------------------------------------------------------------

-  ## NORMAL process

-  ## -- LOCAL_UPDATE updates the source folder from svn

-  ## -- LOCAL_SUBMIT reports to CDash server

-  ## -- LOCAL_SKIP_TEST skips the test process (only builds)

-  ## -- LOCAL_MEMCHECK_TEST executes the Valgrind testing

-  ## -- LOCAL_COVERAGE_TEST executes code coverage process

-  ## --------------------------

-  ctest_start (${MODEL} TRACK ${MODEL})

-  if (LOCAL_UPDATE)

-    ctest_update (SOURCE "${CTEST_SOURCE_DIRECTORY}")

-  endif ()

-  configure_file (${CTEST_SOURCE_DIRECTORY}/config/cmake/CTestCustom.cmake ${CTEST_BINARY_DIRECTORY}/CTestCustom.cmake)

-  ctest_read_custom_files ("${CTEST_BINARY_DIRECTORY}")

-  ctest_configure (BUILD "${CTEST_BINARY_DIRECTORY}" RETURN_VALUE res)

-  if (LOCAL_SUBMIT)

-    ctest_submit (PARTS Update Configure Notes)

-  endif ()

-  if (${res} LESS 0 OR ${res} GREATER 0)

-    file (APPEND ${CTEST_SCRIPT_DIRECTORY}/FailedCTest.txt "Failed Configure: ${res}\n")

-  endif ()

-

-  ctest_build (BUILD "${CTEST_BINARY_DIRECTORY}" APPEND RETURN_VALUE res NUMBER_ERRORS errval)

-  if (LOCAL_SUBMIT)

-    ctest_submit (PARTS Build)

-  endif ()

-  if (${res} LESS 0 OR ${res} GREATER 0 OR ${errval} GREATER 0)

-    file (APPEND ${CTEST_SCRIPT_DIRECTORY}/FailedCTest.txt "Failed ${errval} Build: ${res}\n")

-  endif ()

-

-  if (NOT LOCAL_SKIP_TEST)

-    if (NOT LOCAL_MEMCHECK_TEST)

+  if (NOT WIN32)
+    set (CTEST_BUILD_FLAGS -j${N})
+  endif ()
+  set (ctest_test_args ${ctest_test_args} PARALLEL_LEVEL ${N})
+endif ()
+
+#-----------------------------------------------------------------------------
+# Send the main script as a note.
+list (APPEND CTEST_NOTES_FILES
+    "${CTEST_SCRIPT_DIRECTORY}/${CTEST_SCRIPT_NAME}"
+    "${CMAKE_CURRENT_LIST_FILE}"
+    "${CTEST_SOURCE_DIRECTORY}/config/cmake/cacheinit.cmake"
+)
+
+#-----------------------------------------------------------------------------
+# Check for required variables.
+# --------------------------
+foreach (req
+    CTEST_CMAKE_GENERATOR
+    CTEST_SITE
+    CTEST_BUILD_NAME
+  )
+  if (NOT DEFINED ${req})
+    message (FATAL_ERROR "The containing script must set ${req}")
+  endif ()
+endforeach ()
+
+#-----------------------------------------------------------------------------
+# Initialize the CTEST commands
+#------------------------------
+if (CMAKE_GENERATOR_TOOLSET)
+  set (CTEST_CONFIGURE_TOOLSET  "-T${CMAKE_GENERATOR_TOOLSET}")
+else ()
+  set (CTEST_CONFIGURE_TOOLSET  "")
+endif()
+if (LOCAL_MEMCHECK_TEST)
+  find_program (CTEST_MEMORYCHECK_COMMAND NAMES valgrind)
+  set (CTEST_CONFIGURE_COMMAND
+      "${CTEST_CMAKE_COMMAND} -C \"${CTEST_SOURCE_DIRECTORY}/config/cmake/mccacheinit.cmake\" -DCMAKE_BUILD_TYPE:STRING=${CTEST_CONFIGURATION_TYPE} ${BUILD_OPTIONS} \"-G${CTEST_CMAKE_GENERATOR}\" \"${CTEST_CONFIGURE_TOOLSET}\" \"${CTEST_SOURCE_DIRECTORY}\""
+  )
+else ()
+  if (LOCAL_COVERAGE_TEST)
+    find_program (CTEST_COVERAGE_COMMAND NAMES gcov)
+  endif ()
+  set (CTEST_CONFIGURE_COMMAND
+      "${CTEST_CMAKE_COMMAND} -C \"${CTEST_SOURCE_DIRECTORY}/config/cmake/cacheinit.cmake\" -DCMAKE_BUILD_TYPE:STRING=${CTEST_CONFIGURATION_TYPE} ${BUILD_OPTIONS} \"-G${CTEST_CMAKE_GENERATOR}\" \"${CTEST_CONFIGURE_TOOLSET}\" \"${CTEST_SOURCE_DIRECTORY}\""
+  )
+endif ()
+
+#-----------------------------------------------------------------------------
+## -- set output to english
+set ($ENV{LC_MESSAGES}  "en_EN")
+
+# Print summary information.
+foreach (v
+    CTEST_SITE
+    CTEST_BUILD_NAME
+    CTEST_SOURCE_DIRECTORY
+    CTEST_BINARY_DIRECTORY
+    CTEST_CMAKE_GENERATOR
+    CTEST_CONFIGURATION_TYPE
+    CTEST_GIT_COMMAND
+    CTEST_CHECKOUT_COMMAND
+    CTEST_CONFIGURE_COMMAND
+    CTEST_SCRIPT_DIRECTORY
+    CTEST_USE_LAUNCHERS
+  )
+  set (vars "${vars}  ${v}=[${${v}}]\n")
+endforeach ()
+message (STATUS "Dashboard script configuration:\n${vars}\n")
+
+#-----------------------------------------------------------------------------
+#-----------------------------------------------------------------------------
+  ## NORMAL process
+  ## -- LOCAL_UPDATE updates the source folder from svn
+  ## -- LOCAL_SUBMIT reports to CDash server
+  ## -- LOCAL_SKIP_TEST skips the test process (only builds)
+  ## -- LOCAL_MEMCHECK_TEST executes the Valgrind testing
+  ## -- LOCAL_COVERAGE_TEST executes code coverage process
+  ## --------------------------
+  ctest_start (${MODEL} TRACK ${MODEL})
+  if (LOCAL_UPDATE)
+    ctest_update (SOURCE "${CTEST_SOURCE_DIRECTORY}")
+  endif ()
+  configure_file (${CTEST_SOURCE_DIRECTORY}/config/cmake/CTestCustom.cmake ${CTEST_BINARY_DIRECTORY}/CTestCustom.cmake)
+  ctest_read_custom_files ("${CTEST_BINARY_DIRECTORY}")
+  ctest_configure (BUILD "${CTEST_BINARY_DIRECTORY}" RETURN_VALUE res)
+  if (LOCAL_SUBMIT)
+    ctest_submit (PARTS Update Configure Notes)
+  endif ()
+  if (${res} LESS 0 OR ${res} GREATER 0)
+    file (APPEND ${CTEST_SCRIPT_DIRECTORY}/FailedCTest.txt "Failed Configure: ${res}\n")
+  endif ()
+
+  ctest_build (BUILD "${CTEST_BINARY_DIRECTORY}" APPEND RETURN_VALUE res NUMBER_ERRORS errval)
+  if (LOCAL_SUBMIT)
+    ctest_submit (PARTS Build)
+  endif ()
+  if (${res} LESS 0 OR ${res} GREATER 0 OR ${errval} GREATER 0)
+    file (APPEND ${CTEST_SCRIPT_DIRECTORY}/FailedCTest.txt "Failed ${errval} Build: ${res}\n")
+  endif ()
+
+  if (NOT LOCAL_SKIP_TEST)
+    if (NOT LOCAL_MEMCHECK_TEST)
       if (NOT LOCAL_BATCH_TEST)
         ctest_test (BUILD "${CTEST_BINARY_DIRECTORY}" APPEND ${ctest_test_args} RETURN_VALUE res)
       else ()
diff --git a/config/cmake/scripts/HDF5config.cmake b/config/cmake/scripts/HDF5config.cmake
index dd3b17c..dd3b17c 100755..100644
--- a/config/cmake/scripts/HDF5config.cmake
+++ b/config/cmake/scripts/HDF5config.cmake
diff --git a/config/cmake/scripts/HDF5options.cmake b/config/cmake/scripts/HDF5options.cmake
index d4cc996..d4cc996 100755..100644
--- a/config/cmake/scripts/HDF5options.cmake
+++ b/config/cmake/scripts/HDF5options.cmake
diff --git a/config/cmake_ext_mod/runTest.cmake b/config/cmake_ext_mod/runTest.cmake
index 8181ff0..026131b 100644
--- a/config/cmake_ext_mod/runTest.cmake
+++ b/config/cmake_ext_mod/runTest.cmake
@@ -97,10 +97,10 @@ if (EXISTS ${TEST_FOLDER}/${TEST_OUTPUT}.err)
   string (REGEX REPLACE "^.*_pmi_alps[^\n]+\n" "" TEST_STREAM "${TEST_STREAM}")
 
   if (NOT ERROR_APPEND)
-    # append error output to the stdout output file
+    # write back to original .err file
     file (WRITE ${TEST_FOLDER}/${TEST_OUTPUT}.err "${TEST_STREAM}")
   else ()
-    # write back to original .err file
+    # append error output to the stdout output file
     file (APPEND ${TEST_FOLDER}/${TEST_OUTPUT} "${TEST_STREAM}")
   endif ()
 endif ()
@@ -125,8 +125,11 @@ message (STATUS "COMMAND Error: ${TEST_ERROR}")
 
 # remove special output
 file (READ ${TEST_FOLDER}/${TEST_OUTPUT} TEST_STREAM)
-string (REGEX REPLACE "^.*_pmi_alps[^\n]+\n" "" TEST_STREAM "${TEST_STREAM}")
-file (WRITE ${TEST_FOLDER}/${TEST_OUTPUT} "${TEST_STREAM}")
+string (FIND TEST_STREAM "_pmi_alps" "${TEST_FIND_RESULT}")
+if ("${TEST_FIND_RESULT}" GREATER "0")
+  string (REGEX REPLACE "^.*_pmi_alps[^\n]+\n" "" TEST_STREAM "${TEST_STREAM}")
+  file (WRITE ${TEST_FOLDER}/${TEST_OUTPUT} ${TEST_STREAM})
+endif ()
 
 # if the output file needs Storage text removed
 if (TEST_MASK)
diff --git a/config/conclude.am b/config/conclude.am
index d0dbf3a..9da1da5 100644
--- a/config/conclude.am
+++ b/config/conclude.am
@@ -249,7 +249,7 @@ build-check-p: $(LIB) $(PROGS) $(chk_TESTS)
 	    echo "**** Hint ****";                                            \
 	    echo "Parallel test files reside in the current directory"        \
 	         "by default.";                                               \
-	    echo "Set HDF5_PARAPREFIX to use another directory. E.g.,";       \
+	    echo "Set HDF5_PARAPREFIX to use another directory. e.g.,";       \
 	    echo "    HDF5_PARAPREFIX=/PFS/user/me";                          \
 	    echo "    export HDF5_PARAPREFIX";                                \
 	    echo "    make check";                                            \
diff --git a/configure.ac b/configure.ac
index b761042..eb32435 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3409,7 +3409,9 @@ AC_CONFIG_FILES([src/libhdf5.settings
                  test/test_filenotclosed.sh
                  test/test_filter_plugin.sh
                  test/test_usecases.sh
+                 test/test_vol_plugin.sh
                  testpar/Makefile
+                 testpar/testpflush.sh
                  tools/Makefile
                  tools/lib/Makefile
                  tools/src/Makefile
diff --git a/release_docs/INSTALL_parallel b/release_docs/INSTALL_parallel
index f32fffc..d3d7830 100644
--- a/release_docs/INSTALL_parallel
+++ b/release_docs/INSTALL_parallel
@@ -102,7 +102,7 @@ qsub -I -q debug -l mppwidth=8
 - configure HDF5:
   RUNSERIAL="aprun -q -n 1" RUNPARALLEL="aprun -q -n 6" FC=ftn CC=cc /path/to/source/configure --enable-fortran --enable-parallel --disable-shared
 
-  RUNSERIAL and RUNPARALLEL tells the library how it should launch programs that are part of the build procedure.
+  RUNSERIAL and RUNPARALLEL tell the library how it should launch programs that are part of the build procedure.
 
 - Compile HDF5: 
   gmake
@@ -155,12 +155,16 @@ to run a parallel application on one processor and on many processors. If the
 compiler is `mpicc' and the user hasn't specified values for RUNSERIAL and
 RUNPARALLEL then configure chooses `mpiexec' from the same directory as `mpicc':
 
-    RUNSERIAL:    /usr/local/mpi/bin/mpiexec -np 1
-    RUNPARALLEL:  /usr/local/mpi/bin/mpiexec -np $${NPROCS:=6}
+    RUNSERIAL:    mpiexec -n 1
+    RUNPARALLEL:  mpiexec -n $${NPROCS:=6}
 
 The `$${NPROCS:=6}' will be substituted with the value of the NPROCS
 environment variable at the time `make check' is run (or the value 6).
 
+Note that some MPI implementations (e.g. OpenMPI 4.0) disallow oversubscribing
+nodes by default so you'll have to either set NPROCS equal to the number of
+processors available (or fewer) or redefine RUNPARALLEL with appropriate
+flag(s) (--oversubscribe in OpenMPI).
 
 4. Parallel test suite
 ----------------------
diff --git a/src/H5Dint.c b/src/H5Dint.c
index 6bb3343..7eb1aaf 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -25,6 +25,7 @@
 #include "H5CXprivate.h"        /* API Contexts                             */
 #include "H5Dpkg.h"             /* Datasets                                 */
 #include "H5Eprivate.h"         /* Error handling                           */
+#include "H5Fprivate.h"         /* Files                                    */
 #include "H5FLprivate.h"        /* Free Lists                               */
 #include "H5FOprivate.h"        /* File objects                             */
 #include "H5Iprivate.h"         /* IDs                                      */
@@ -59,6 +60,9 @@ static herr_t H5D__init_storage(const H5D_io_info_t *io_info, hbool_t full_overw
         hsize_t old_dim[]);
 static herr_t H5D__append_flush_setup(H5D_t *dset, hid_t dapl_id);
 static herr_t H5D__close_cb(H5VL_object_t *dset_vol_obj);
+static herr_t H5D__use_minimized_dset_headers(H5F_t *file, H5D_t *dset, hbool_t *minimize);
+static herr_t H5D__prepare_minimized_oh(H5F_t *file, H5D_t *dset, H5O_loc_t *oloc);
+static size_t H5D__calculate_minimum_header_size(H5F_t *file, H5D_t *dset, H5O_t *ohdr);
 
 
 /*********************/
@@ -658,6 +662,211 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:   H5D__use_minimized_dset_headers
+ *
+ * Purpose:    Compartmentalize check for file- or dcpl-set values indicating
+ *             to create a "minimized" dataset object header.
+ *             Upon success, write resulting value to out pointer `minimize`.
+ *
+ * Return:     Success: SUCCEED (0) (non-negative value)
+ *             Failure: FAIL (-1) (negative value)
+ *
+ * Programmer: Jacob Smith
+ *             16 August 2018
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5D__use_minimized_dset_headers(H5F_t *file, H5D_t *dset, hbool_t *minimize)
+{
+    H5P_genplist_t *plist     = NULL;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI_NOINIT;
+
+    HDassert(file);
+    HDassert(dset);
+    HDassert(minimize);
+
+    plist = H5P_object_verify(dset->shared->dcpl_id, H5P_DATASET_CREATE);
+    if(NULL == plist)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "problem getting dcpl")
+    if(H5P_get(plist, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, minimize) == FAIL)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get minimize value from dcpl")
+
+    if(FALSE == *minimize)
+        *minimize = H5F_get_min_dset_ohdr(file);
+
+done:
+    if(FAIL == ret_value)
+        *minimize = FALSE;
+    FUNC_LEAVE_NOAPI(ret_value);
+} /* H5D__use_minimized_dset_headers */
+
+
+/*-------------------------------------------------------------------------
+ * Function:   H5D__calculate_minimium_header_size
+ *
+ * Purpose:    Calculate the size required for the minimized object header.
+ *
+ * Return:     Success: Positive value > 0
+ *             Failure: 0
+ *
+ * Programmer: Jacob Smith
+ *             16 August 2018
+ *-------------------------------------------------------------------------
+ */
+static size_t
+H5D__calculate_minimum_header_size(H5F_t *file, H5D_t *dset, H5O_t *ohdr)
+{
+    H5T_t      *type             = NULL;
+    H5O_fill_t *fill_prop        = NULL;
+    hbool_t     use_at_least_v18 = FALSE;
+    const char  continuation[1]  = ""; /* requred for work-around */
+    size_t      get_value        = 0;
+    size_t      ret_value        = 0;
+
+    FUNC_ENTER_NOAPI_NOINIT;
+
+    HDassert(file);
+    HDassert(dset);
+    HDassert(ohdr);
+
+    type = dset->shared->type;
+    fill_prop = &(dset->shared->dcpl_cache.fill);
+    use_at_least_v18 = (H5F_LOW_BOUND(file) >= H5F_LIBVER_V18);
+
+    /* Datatype message size */
+    get_value = H5O_msg_size_oh(file, ohdr, H5O_DTYPE_ID, type, 0);
+    if (get_value == 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "Can't get size of datatype message")
+    ret_value += get_value;
+
+    /* Shared Dataspace message size */
+    get_value = H5O_msg_size_oh(file, ohdr, H5O_SDSPACE_ID, dset->shared->space, 0);
+    if (get_value == 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of dataspace message")
+    ret_value += get_value;
+
+    /* "Layout" message size */
+    get_value = H5O_msg_size_oh(file, ohdr, H5O_LAYOUT_ID, &dset->shared->layout, 0);
+    if (get_value == 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of layout message")
+    ret_value += get_value;
+
+    /* Fill Value message size */
+    get_value = H5O_msg_size_oh(file, ohdr, H5O_FILL_NEW_ID, fill_prop, 0);
+    if (get_value == 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of fill value message")
+    ret_value += get_value;
+
+    /* "Continuation" message size */
+    /* message pointer "continuation" is unused by raw get function, however,
+     * a null pointer would be intercepted by an assert in H5O_msg_size_oh().
+     */
+    get_value = H5O_msg_size_oh(file, ohdr, H5O_CONT_ID, continuation, 0);
+    if (get_value == 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of continuation message")
+    ret_value += get_value;
+
+    /* Fill Value (backwards compatability) message size */
+    if(fill_prop->buf && !use_at_least_v18) {
+        H5O_fill_t old_fill_prop; /* Copy for writing "old" fill value */
+
+        /* Shallow copy the fill value property */
+        /* guards against shared component modification */
+        HDmemcpy(&old_fill_prop, fill_prop, sizeof(old_fill_prop));
+
+        if (H5O_msg_reset_share(H5O_FILL_ID, &old_fill_prop) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't reset the copied fill property")
+
+        get_value = H5O_msg_size_oh(file, ohdr, H5O_FILL_ID, &old_fill_prop, 0);
+        if (get_value == 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of fill value (backwards compat) message")
+        ret_value += get_value;
+    }
+
+    /* Filter/Pipeline message size */
+    if(H5D_CHUNKED == dset->shared->layout.type) {
+        H5O_pline_t *pline = &dset->shared->dcpl_cache.pline;
+        if(pline->nused > 0) {
+            get_value = H5O_msg_size_oh(file, ohdr, H5O_PLINE_ID, pline, 0);
+            if (get_value == 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of filter message")
+            ret_value += get_value;
+        }
+    }
+
+    /* External File Link message size */
+    if(dset->shared->dcpl_cache.efl.nused > 0) {
+        get_value = H5O_msg_size_oh(file, ohdr, H5O_EFL_ID, &dset->shared->dcpl_cache.efl, 0);
+        if (get_value == 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of external file link message")
+        ret_value += get_value;
+    }
+
+    /* Modification Time message size */
+    if(H5O_HDR_STORE_TIMES & H5O_OH_GET_FLAGS(ohdr)) {
+        HDassert(H5O_OH_GET_VERSION(ohdr) >= 1); /* 1 :: H5O_VERSION_1 (H5Opkg.h) */
+
+        if(H5O_OH_GET_VERSION(ohdr) == 1) {
+            /* v1 object headers store modification time as a message */
+            time_t mtime;
+            get_value = H5O_msg_size_oh(file, ohdr, H5O_MTIME_NEW_ID, &mtime, 0);
+            if (get_value == 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't get size of modification time message")
+            ret_value += get_value;
+        }
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value);
+} /* H5D__calculate_minimum_header_size */
+
+
+/*-------------------------------------------------------------------------
+ * Function:   H5D__prepare_minimized_oh
+ *
+ * Purpose:    Create an object header (H5O_t) allocated with the smallest
+ *             possible size.
+ *
+ * Return:     Success: SUCCEED (0) (non-negative value)
+ *             Failure: FAIL (-1) (negative value)
+ *
+ * Programmer: Jacob Smith
+ *             16 August 2018
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5D__prepare_minimized_oh(H5F_t *file, H5D_t *dset, H5O_loc_t *oloc)
+{
+    H5O_t  *oh        = NULL;
+    size_t  ohdr_size = 0;
+    herr_t  ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI_NOINIT;
+
+    HDassert(file);
+    HDassert(dset);
+    HDassert(oloc);
+
+    oh = H5O__create_ohdr(file, dset->shared->dcpl_id);
+    if(NULL == oh)
+        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "can't instantiate object header")
+
+    ohdr_size = H5D__calculate_minimum_header_size(file, dset, oh);
+    if (ohdr_size == 0)
+       HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "computed header size is invalid")
+
+    /* Special allocation of space for compact datsets is handled by the call here. */
+    if(H5O__apply_ohdr(file, oh, dset->shared->dcpl_id, ohdr_size, (size_t)1, oloc) == FAIL)
+        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "can't apply object header to file")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value);
+} /* H5D__prepare_minimized_oh */
+
+
+/*-------------------------------------------------------------------------
  * Function: H5D__update_oh_info
  *
  * Purpose:  Create and fill object header for dataset
@@ -669,17 +878,18 @@ done:
 static herr_t
 H5D__update_oh_info(H5F_t *file, H5D_t *dset, hid_t dapl_id)
 {
-    H5O_t              *oh = NULL;      /* Pointer to dataset's object header */
-    size_t              ohdr_size = H5D_MINHDR_SIZE;    /* Size of dataset's object header */
-    H5O_loc_t          *oloc = NULL;    /* Dataset's object location */
-    H5O_layout_t       *layout;         /* Dataset's layout information */
-    H5T_t              *type;           /* Dataset's datatype */
-    H5O_fill_t         *fill_prop;      /* Pointer to dataset's fill value information */
-    H5D_fill_value_t    fill_status;    /* Fill value status */
-    hbool_t             fill_changed = FALSE;   /* Flag indicating the fill value was changed */
-    hbool_t             layout_init = FALSE;    /* Flag to indicate that chunk information was initialized */
-    hbool_t             use_at_least_v18;       /* Flag indicating to use at least v18 format versions */
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5O_t            *oh = NULL;      /* Pointer to dataset's object header */
+    size_t            ohdr_size = H5D_MINHDR_SIZE;    /* Size of dataset's object header */
+    H5O_loc_t        *oloc = NULL;    /* Dataset's object location */
+    H5O_layout_t     *layout;         /* Dataset's layout information */
+    H5T_t            *type;           /* Dataset's datatype */
+    H5O_fill_t       *fill_prop;      /* Pointer to dataset's fill value information */
+    H5D_fill_value_t  fill_status;    /* Fill value status */
+    hbool_t           fill_changed = FALSE;   /* Flag indicating the fill value was changed */
+    hbool_t           layout_init = FALSE;    /* Flag to indicate that chunk information was initialized */
+    hbool_t           use_at_least_v18;       /* Flag indicating to use at least v18 format versions */
+    hbool_t           minimize_header = FALSE;
+    herr_t            ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
 
@@ -747,13 +957,24 @@ H5D__update_oh_info(H5F_t *file, H5D_t *dset, hid_t dapl_id)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set fill value info")
     } /* end if */
 
-    /* Add the dataset's raw data size to the size of the header, if the raw data will be stored as compact */
-    if(layout->type == H5D_COMPACT)
-        ohdr_size += layout->storage.u.compact.size;
+    if(H5D__use_minimized_dset_headers(file, dset, &minimize_header) == FAIL)
+        HGOTO_ERROR(H5E_ARGS, H5E_CANTGET, FAIL, "can't get minimize settings")
+
+    if(TRUE == minimize_header) {
+        if(H5D__prepare_minimized_oh(file, dset, oloc) == FAIL)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't create minimized dataset object header")
+    } else {
+        /* Add the dataset's raw data size to the size of the header, if the
+         * raw data will be stored as compact
+         */
+        if(H5D_COMPACT == layout->type)
+            ohdr_size += layout->storage.u.compact.size;
+
+        /* Create an object header for the dataset */
+        if(H5O_create(file, ohdr_size, (size_t)1, dset->shared->dcpl_id, oloc/*out*/) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset object header")
+    } /* If use minimum/standard object header space */
 
-    /* Create an object header for the dataset */
-    if(H5O_create(file, ohdr_size, (size_t)1, dset->shared->dcpl_id, oloc/*out*/) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset object header")
     HDassert(file == dset->oloc.file);
 
     /* Pin the object header */
@@ -910,7 +1131,7 @@ H5D__build_file_prefix(const H5D_t *dset, hid_t dapl_id, const char *prefix_type
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
     } /* end if */
     else {
-        if (HDstrncmp(prefix, "${ORIGIN}", HDstrlen("${ORIGIN}")) == 0) {
+        if(HDstrncmp(prefix, "${ORIGIN}", HDstrlen("${ORIGIN}")) == 0) {
             /* Replace ${ORIGIN} at beginning of prefix by directory of HDF5 file */
             filepath_len = HDstrlen(filepath);
             prefix_len = HDstrlen(prefix);
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 4e9cda8..aaa3db2 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -45,6 +45,7 @@
 #define H5D_CRT_FILL_VALUE_NAME    "fill_value"          /* Fill value */
 #define H5D_CRT_ALLOC_TIME_STATE_NAME "alloc_time_state" /* Space allocation time state */
 #define H5D_CRT_EXT_FILE_LIST_NAME "efl"                 /* External file list */
+#define H5D_CRT_MIN_DSET_HDR_SIZE_NAME "dset_oh_minimize"/* Minimize object header */
 
 /* ========  Dataset access property names ======== */
 #define H5D_ACS_DATA_CACHE_NUM_SLOTS_NAME   "rdcc_nslots"    /* Size of raw data chunk cache(slots) */
diff --git a/src/H5F.c b/src/H5F.c
index b17d94f..0ff3f1f 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -1335,7 +1335,7 @@ H5Fget_metadata_read_retry_info(hid_t file_id, H5F_retry_info_t *info)
     H5TRACE2("e", "i*x", file_id, info);
 
     /* Check args */
-    if (!info)
+    if(!info)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no info struct")
 
     /* Get the file pointer */
@@ -1822,3 +1822,89 @@ done:
     FUNC_LEAVE_API(ret_value)
 } /* H5Fincrement_filesize() */
 
+
+/*-------------------------------------------------------------------------
+ * Function: H5Fget_dset_no_attrs_hint
+ *
+ * Purpose:
+ *
+ *     Get the file-level setting to create minimized dataset object headers.
+ *     Result is stored at pointer `minimize`.
+ *
+ * Return:
+ *
+ *     Success: SUCCEED (0) (non-negative value)
+ *     Failure: FAIL (-1) (negative value)
+ *
+ * Programmer:
+ *
+ *     Jacob Smith
+ *     15 August 2018
+ *
+ * Changes: None.
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Fget_dset_no_attrs_hint(hid_t file_id, hbool_t *minimize)
+{
+    H5VL_object_t  *vol_obj   = NULL;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "i*b", file_id, minimize);
+
+    if(NULL == minimize)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "out pointer 'minimize' cannot be NULL")
+
+    vol_obj = (H5VL_object_t *)H5I_object_verify(file_id, H5I_FILE);
+    if(NULL == vol_obj)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
+
+    if(H5VL_file_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG, minimize) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTSET, FAIL, "unable to set file's dataset header minimization flag")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Fget_dset_no_attrs_hint */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5Fset_dset_no_attrs_hint
+ *
+ * Purpose:
+ *
+ *     Set the file-level setting to create minimized dataset object headers.
+ *
+ * Return:
+ *
+ *     Success: SUCCEED (0) (non-negative value)
+ *     Failure: FAIL (-1) (negative value)
+ *
+ * Programmer:
+ *
+ *     Jacob Smith
+ *     15 August 2018
+ *
+ * Changes: None.
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Fset_dset_no_attrs_hint(hid_t file_id, hbool_t minimize)
+{
+    H5VL_object_t *vol_obj   = NULL;
+    herr_t         ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ib", file_id, minimize);
+
+    vol_obj = (H5VL_object_t *)H5I_object_verify(file_id, H5I_FILE);
+    if(NULL == vol_obj)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
+
+    if(H5VL_file_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG, minimize) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTSET, FAIL, "unable to set file's dataset header minimization flag")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Fset_dset_no_attrs_hint */
+
diff --git a/src/H5FDcore.c b/src/H5FDcore.c
index ec6b2a7..ed05e95 100644
--- a/src/H5FDcore.c
+++ b/src/H5FDcore.c
@@ -420,8 +420,8 @@ done:
  * Purpose:     Initialize this driver by registering the driver with the
  *              library.
  *
- * Return:      Success:    The driver ID for the core driver.
- *              Failure:    Negative.
+ * Return:      Success:    The driver ID for the core driver
+ *              Failure:    H5I_INVALID_HID
  *
  * Programmer:  Robb Matzke
  *              Thursday, July 29, 1999
@@ -433,7 +433,7 @@ H5FD_core_init(void)
 {
     hid_t ret_value = H5I_INVALID_HID;  /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
     if(H5I_VFL != H5I_get_type(H5FD_CORE_g))
         H5FD_CORE_g = H5FD_register(&H5FD_core_g, sizeof(H5FD_class_t), FALSE);
diff --git a/src/H5FDdirect.c b/src/H5FDdirect.c
index d1a8fc8..10c368a 100644
--- a/src/H5FDdirect.c
+++ b/src/H5FDdirect.c
@@ -206,30 +206,27 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:  H5FD_direct_init
+ * Function:    H5FD_direct_init
  *
- * Purpose:  Initialize this driver by registering the driver with the
- *    library.
+ * Purpose:     Initialize this driver by registering the driver with the
+ *              library.
  *
- * Return:  Success:  The driver ID for the direct driver.
- *
- *    Failure:  Negative.
+ * Return:      Success:    The driver ID for the direct driver
+ *              Failure:    H5I_INVALID_HID
  *
  * Programmer:  Raymond Lu
  *              Wednesday, 20 September 2006
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 hid_t
 H5FD_direct_init(void)
 {
-    hid_t ret_value;        /* Return value */
+    hid_t ret_value = H5I_INVALID_HID;        /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
-    if (H5I_VFL!=H5I_get_type(H5FD_DIRECT_g))
+    if (H5I_VFL != H5I_get_type(H5FD_DIRECT_g))
         H5FD_DIRECT_g = H5FD_register(&H5FD_direct_g,sizeof(H5FD_class_t),FALSE);
 
     /* Set return value */
@@ -237,7 +234,7 @@ H5FD_direct_init(void)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD_direct_init() */
 
 
 /*---------------------------------------------------------------------------
diff --git a/src/H5FDfamily.c b/src/H5FDfamily.c
index e52a71a..4d40cf3 100644
--- a/src/H5FDfamily.c
+++ b/src/H5FDfamily.c
@@ -171,28 +171,25 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_family_init
+ * Function:    H5FD_family_init
  *
- * Purpose:	Initialize this driver by registering the driver with the
- *		library.
+ * Purpose:     Initialize this driver by registering the driver with the
+ *              library.
  *
- * Return:	Success:	The driver ID for the family driver.
+ * Return:      Success:    The driver ID for the family driver
+ *              Failure:    H5I_INVALID_HID
  *
- *		Failure:	Negative
- *
- * Programmer:	Robb Matzke
+ * Programmer:  Robb Matzke
  *              Wednesday, August  4, 1999
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 hid_t
 H5FD_family_init(void)
 {
-    hid_t ret_value = H5FD_FAMILY_g;   /* Return value */
+    hid_t ret_value = H5I_INVALID_HID;   /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
     if(H5I_VFL != H5I_get_type(H5FD_FAMILY_g))
         H5FD_FAMILY_g = H5FD_register(&H5FD_family_g, sizeof(H5FD_class_t), FALSE);
diff --git a/src/H5FDlog.c b/src/H5FDlog.c
index cd9ab0e..97d1b41 100644
--- a/src/H5FDlog.c
+++ b/src/H5FDlog.c
@@ -252,8 +252,8 @@ done:
  * Purpose:     Initialize this driver by registering the driver with the
  *              library.
  *
- * Return:      Success:    The driver ID for the log driver.
- *              Failure:    Negative.
+ * Return:      Success:    The driver ID for the log driver
+ *              Failure:    H5I_INVALID_HID
  *
  * Programmer:  Robb Matzke
  *              Thursday, July 29, 1999
@@ -265,7 +265,7 @@ H5FD_log_init(void)
 {
     hid_t ret_value = H5I_INVALID_HID;  /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
     if(H5I_VFL != H5I_get_type(H5FD_LOG_g))
         H5FD_LOG_g = H5FD_register(&H5FD_log_g, sizeof(H5FD_class_t), FALSE);
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index c04906e..a5180d0 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -187,15 +187,15 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_init
+ * Function:    H5FD_mpio_init
  *
- * Purpose:	Initialize this driver by registering the driver with the
- *		library.
+ * Purpose:     Initialize this driver by registering the driver with the
+ *              library.
  *
- * Return:	Success:	The driver ID for the mpio driver.
- *		Failure:	Negative.
+ * Return:      Success:    The driver ID for the mpio driver
+ *              Failure:    H5I_INVALID_HID
  *
- * Programmer:	Robb Matzke
+ * Programmer:  Robb Matzke
  *              Thursday, August 5, 1999
  *
  *-------------------------------------------------------------------------
@@ -206,10 +206,10 @@ H5FD_mpio_init(void)
 #ifdef H5FDmpio_DEBUG
     static int H5FD_mpio_Debug_inited = 0;
 #endif /* H5FDmpio_DEBUG */
-    const char *s;              /* String for environment variables */
-    hid_t ret_value;        	/* Return value */
+    const char *s;                          /* String for environment variables */
+    hid_t ret_value = H5I_INVALID_HID;      /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
     /* Register the MPI-IO VFD, if it isn't already */
     if(H5I_VFL != H5I_get_type(H5FD_MPIO_g))
@@ -217,8 +217,10 @@ H5FD_mpio_init(void)
 
     /* Allow MPI buf-and-file-type optimizations? */
     s = HDgetenv("HDF5_MPI_OPT_TYPES");
-    if(s && HDisdigit(*s))
-        H5FD_mpi_opt_types_g = (hbool_t)HDstrtol(s, NULL, 0);
+    if(s && HDisdigit(*s)) {
+        long env_val = HDstrtol(s, NULL, 0);
+        H5FD_mpi_opt_types_g = (0 == env_val) ? FALSE : TRUE;
+    }
 
 #ifdef H5FDmpio_DEBUG
     if(!H5FD_mpio_Debug_inited) {
@@ -226,12 +228,12 @@ H5FD_mpio_init(void)
         s = HDgetenv("H5FD_mpio_Debug");
         if(s) {
             /* Set debug mask */
-	    while(*s) {
-		H5FD_mpio_Debug[(int)*s]++;
-		s++;
-	    } /* end while */
+            while(*s) {
+                H5FD_mpio_Debug[(int)*s]++;
+                s++;
+            } /* end while */
         } /* end if */
-	H5FD_mpio_Debug_inited++;
+        H5FD_mpio_Debug_inited++;
     } /* end if */
 #endif /* H5FDmpio_DEBUG */
 
diff --git a/src/H5FDmulti.c b/src/H5FDmulti.c
index e8dde50..fac0909 100644
--- a/src/H5FDmulti.c
+++ b/src/H5FDmulti.c
@@ -26,11 +26,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-/* Disable certain warnings in PC-Lint: */
-/*lint --emacro( {534, 830}, H5P_DEFAULT, H5P_FILE_ACCESS, H5P_DATASET_XFER) */
-/*lint --emacro( {534, 830}, H5FD_MULTI) */
-/*lint -esym( 534, H5Eclear2, H5Epush2) */
-
 #include "hdf5.h"
 
 
@@ -211,16 +206,15 @@ my_strdup(const char *s)
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_multi_init
- *
- * Purpose:	Initialize this driver by registering the driver with the
- *		library.
+ * Function:    H5FD_multi_init
  *
- * Return:	Success:	The driver ID for the multi driver.
+ * Purpose:     Initialize this driver by registering the driver with the
+ *              library.
  *
- *		Failure:	Negative
+ * Return:      Success:    The driver ID for the multi driver
+ *              Failure:    H5I_INVALID_HID
  *
- * Programmer:	Robb Matzke
+ * Programmer:  Robb Matzke
  *              Wednesday, August  4, 1999
  *
  *-------------------------------------------------------------------------
@@ -231,11 +225,11 @@ H5FD_multi_init(void)
     /* Clear the error stack */
     H5Eclear2(H5E_DEFAULT);
 
-    if(H5I_VFL!=H5Iget_type(H5FD_MULTI_g))
+    if(H5I_VFL != H5Iget_type(H5FD_MULTI_g))
         H5FD_MULTI_g = H5FDregister(&H5FD_multi_g);
 
     return H5FD_MULTI_g;
-}
+} /* end H5FD_multi_init() */
 
 
 /*---------------------------------------------------------------------------
diff --git a/src/H5FDsec2.c b/src/H5FDsec2.c
index 06c008d..c507387 100644
--- a/src/H5FDsec2.c
+++ b/src/H5FDsec2.c
@@ -208,8 +208,8 @@ done:
  * Purpose:     Initialize this driver by registering the driver with the
  *              library.
  *
- * Return:      Success:    The driver ID for the sec2 driver.
- *              Failure:    Negative
+ * Return:      Success:    The driver ID for the sec2 driver
+ *              Failure:    H5I_INVALID_HID
  *
  * Programmer:  Robb Matzke
  *              Thursday, July 29, 1999
@@ -221,7 +221,7 @@ H5FD_sec2_init(void)
 {
     hid_t ret_value = H5I_INVALID_HID;          /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
 
     if(H5I_VFL != H5I_get_type(H5FD_SEC2_g))
         H5FD_SEC2_g = H5FD_register(&H5FD_sec2_g, sizeof(H5FD_class_t), FALSE);
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 8de1769..cca46d0 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -3715,3 +3715,27 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_get_file_id() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_set_min_dset_ohdr
+ *
+ * Purpose:     Set the crt_dset_ohdr_flag field with a new value.
+ *
+ * Return:      SUCCEED/FAIL
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5F_set_min_dset_ohdr(H5F_t *f, hbool_t minimize)
+{
+    /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(f->shared);
+
+    f->shared->crt_dset_min_ohdr_flag = minimize;
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* H5F_set_min_dset_ohdr() */
+
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 4ad2c55..335d0a7 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -358,6 +358,7 @@ struct H5F_file_t {
 
     /* Object flush info */
     H5F_object_flush_t 	object_flush;	    /* Information for object flush callback */
+    hbool_t crt_dset_min_ohdr_flag; /* flag to minimize created dataset object header */
 };
 
 /*
@@ -382,7 +383,6 @@ struct H5F_t {
 #endif /* H5_HAVE_PARALLEL */
 };
 
-
 /*****************************/
 /* Package Private Variables */
 /*****************************/
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 85f0d15..5f7a1b2 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -331,6 +331,8 @@ typedef struct H5F_t H5F_t;
 #define H5F_POINT_OF_NO_RETURN(F) ((F)->shared->fs.point_of_no_return)
 #define H5F_FIRST_ALLOC_DEALLOC(F) ((F)->shared->first_alloc_dealloc)
 #define H5F_EOA_PRE_FSM_FSALLOC(F) ((F)->shared->eoa_pre_fsm_fsalloc)
+#define H5F_GET_MIN_DSET_OHDR(F) ((F)->shared->crt_dset_min_ohdr_flag)
+#define H5F_SET_MIN_DSET_OHDR(F, V) ((F)->shared->crt_dset_min_ohdr_flag = (V))
 #else /* H5F_MODULE */
 #define H5F_LOW_BOUND(F)        (H5F_get_low_bound(F))
 #define H5F_HIGH_BOUND(F)       (H5F_get_high_bound(F))
@@ -388,6 +390,8 @@ typedef struct H5F_t H5F_t;
 #define H5F_POINT_OF_NO_RETURN(F) (H5F_get_point_of_no_return(F))
 #define H5F_FIRST_ALLOC_DEALLOC(F) (H5F_get_first_alloc_dealloc(F))
 #define H5F_EOA_PRE_FSM_FSALLOC(F) (H5F_get_eoa_pre_fsm_fsalloc(F))
+#define H5F_GET_MIN_DSET_OHDR(F) (H5F_get_min_dset_ohdr(F))
+#define H5F_SET_MIN_DSET_OHDR(F, V) (H5F_set_min_dset_ohdr((F), (V)))
 #endif /* H5F_MODULE */
 
 
@@ -740,6 +744,8 @@ H5_DLL hsize_t H5F_get_pgend_meta_thres(const H5F_t *f);
 H5_DLL hbool_t H5F_get_point_of_no_return(const H5F_t *f);
 H5_DLL hbool_t H5F_get_first_alloc_dealloc(const H5F_t *f);
 H5_DLL haddr_t H5F_get_eoa_pre_fsm_fsalloc(const H5F_t *f);
+H5_DLL hbool_t H5F_get_min_dset_ohdr(const H5F_t *f);
+H5_DLL herr_t H5F_set_min_dset_ohdr(H5F_t *f, hbool_t minimize);
 
 /* Functions than retrieve values set/cached from the superblock/FCPL */
 H5_DLL haddr_t H5F_get_base_addr(const H5F_t *f);
diff --git a/src/H5Fpublic.h b/src/H5Fpublic.h
index e1b6dc3..c4bf0b4 100644
--- a/src/H5Fpublic.h
+++ b/src/H5Fpublic.h
@@ -217,7 +217,6 @@ typedef struct H5F_retry_info_t {
 /* Callback for H5Pset_object_flush_cb() in a file access property list */
 typedef herr_t (*H5F_flush_cb_t)(hid_t object_id, void *udata);
 
-
 /*********************/
 /* Public Prototypes */
 /*********************/
@@ -275,6 +274,8 @@ H5_DLL herr_t H5Freset_page_buffering_stats(hid_t file_id);
 H5_DLL herr_t H5Fget_page_buffering_stats(hid_t file_id, unsigned accesses[2],
     unsigned hits[2], unsigned misses[2], unsigned evictions[2], unsigned bypasses[2]);
 H5_DLL herr_t H5Fget_mdc_image_info(hid_t file_id, haddr_t *image_addr, hsize_t *image_size);
+H5_DLL herr_t H5Fget_dset_no_attrs_hint(hid_t file_id, hbool_t *minimize);
+H5_DLL herr_t H5Fset_dset_no_attrs_hint(hid_t file_id, hbool_t minimize);
 
 #ifdef H5_HAVE_PARALLEL
 H5_DLL herr_t H5Fset_mpi_atomicity(hid_t file_id, hbool_t flag);
diff --git a/src/H5Fquery.c b/src/H5Fquery.c
index 3147e95..103ad3b 100644
--- a/src/H5Fquery.c
+++ b/src/H5Fquery.c
@@ -514,6 +514,25 @@ H5F_sym_leaf_k(const H5F_t *f)
 
 
 /*-------------------------------------------------------------------------
+ * Function: H5F_get_min_dset_ohdr
+ *
+ * Purpose:  Get the setting flag for minimized dataset object headers
+ *
+ * Return:   TRUE/FALSE as set in file
+ *-------------------------------------------------------------------------
+ */
+hbool_t
+H5F_get_min_dset_ohdr(const H5F_t *f)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    HDassert(f);
+
+    FUNC_LEAVE_NOAPI(f->shared->crt_dset_min_ohdr_flag)
+} /* end H5F_get_min_dset_ohdr */
+
+
+/*-------------------------------------------------------------------------
  * Function: H5F_Kvalue
  *
  * Purpose:  Replaced a macro to retrieve a B-tree key value for a certain
diff --git a/src/H5Oint.c b/src/H5Oint.c
index a97a2fd..2503eb7 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -83,7 +83,6 @@ static herr_t H5O__visit_cb(hid_t group, const char *name, const H5L_info_t *lin
     void *_udata);
 static const H5O_obj_class_t *H5O__obj_class_real(const H5O_t *oh);
 
-
 /*********************/
 /* Package Variables */
 /*********************/
@@ -277,99 +276,183 @@ done:
  *		matzke@llnl.gov
  *		Aug  5 1997
  *
+ * Changes:     2018 August 17
+ *              Jacob Smith 
+ *              Refactor out the operations into two separate steps --
+ *              preparation and application -- to facilitate overriding the
+ *              library-default size allocated for the object header. This
+ *              function is retained as a wrapper, to minimize changes to
+ *              unaffected calling functions.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc, hid_t ocpl_id,
-    H5O_loc_t *loc/*out*/)
+H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc, hid_t ocpl_id, H5O_loc_t *loc /*out*/)
 {
-    H5P_genplist_t  *oc_plist;          /* Object creation property list */
-    H5O_t      *oh = NULL;              /* Object header created */
-    haddr_t     oh_addr;                /* Address of initial object header */
-    size_t      oh_size;                /* Size of initial object header */
-    uint8_t	oh_flags;		/* Object header's initial status flags */
-    unsigned    insert_flags = H5AC__NO_FLAGS_SET; /* Flags for inserting object header into cache */
-    hbool_t     store_msg_crt_idx;      /* Whether to always store message creation indices for this file */
-    herr_t      ret_value = SUCCEED;    /* return value */
+    H5O_t  *oh        = NULL;
+    herr_t  ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    /* check args */
     HDassert(f);
     HDassert(loc);
     HDassert(TRUE == H5P_isa_class(ocpl_id, H5P_OBJECT_CREATE));
 
+    /* create object header in freelist
+     * header version is set internally
+     */
+    oh = H5O__create_ohdr(f, ocpl_id);
+    if(NULL == oh)
+        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "Can't instantiate object header")
+
+    /* apply object header information to file
+     */
+    if(H5O__apply_ohdr(f, oh, ocpl_id, size_hint, initial_rc, loc) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "Can't apply object header to file")
+
+done:
+    if((FAIL == ret_value) && (NULL != oh) && (H5O__free(oh) < 0))
+        HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "can't delete object header")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5O_create() */
+
+
+/*-----------------------------------------------------------------------------
+ * Function:   H5O__create_ohdr
+ *
+ * Purpose:    Create the object header, set version and flags.
+ *
+ * Return:     Success: Pointer to the newly-crated header object.
+ *             Failure: NULL
+ *
+ * Programmer: Jacob Smith
+ *             2018 August 17 
+ *
+ *-----------------------------------------------------------------------------
+ */
+H5O_t *
+H5O__create_ohdr(H5F_t *f, hid_t ocpl_id)
+{
+    H5P_genplist_t *oc_plist;
+    H5O_t          *oh = NULL;        /* Object header in Freelist */
+    uint8_t         oh_flags;         /* Initial status flags */
+    H5O_t          *ret_value = NULL;
+
+    FUNC_ENTER_NOAPI(NULL)
+
+    HDassert(f);
+    HDassert(TRUE == H5P_isa_class(ocpl_id, H5P_OBJECT_CREATE));
+
     /* Check for invalid access request */
     if(0 == (H5F_INTENT(f) & H5F_ACC_RDWR))
-        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "no write intent on file")
+        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, NULL, "no write intent on file")
 
-    /* Make certain we allocate at least a reasonable size for the object header */
-    size_hint = H5O_ALIGN_F(f, MAX(H5O_MIN_SIZE, size_hint));
+    oh = H5FL_CALLOC(H5O_t);
+    if(NULL == oh)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
-    /* Get the property list */
-    if(NULL == (oc_plist = (H5P_genplist_t *)H5I_object(ocpl_id)))
-        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a property list")
+    oc_plist = (H5P_genplist_t *)H5I_object(ocpl_id);
+    if(NULL == oc_plist)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, NULL, "not a property list")
 
     /* Get any object header status flags set by properties */
     if(H5P_get(oc_plist, H5O_CRT_OHDR_FLAGS_NAME, &oh_flags) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get object header flags")
 
-    /* Allocate the object header and zero out header fields */
-    if(NULL == (oh = H5FL_CALLOC(H5O_t)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+    if(H5O_set_version(f, oh, oh_flags, H5F_STORE_MSG_CRT_IDX(f)) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, NULL, "can't set version of object header")
+
+    oh->flags = oh_flags;
+
+    ret_value = oh;
+
+done:
+    if((NULL == ret_value) && (NULL != oh) && (H5O__free(oh) < 0))
+        HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, NULL, "can't delete object header")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5O__create_ohdr() */
 
-    /* Initialize file-specific information for object header */
-    store_msg_crt_idx = H5F_STORE_MSG_CRT_IDX(f);
+
+/*-----------------------------------------------------------------------------
+ * Function:   H5O__apply_ohdr
+ *
+ * Purpose:    Initialize and set the object header in the file.
+ *             Record some information at `loc_out`.
+ *
+ * Return:     Success: SUCCEED (0) (non-negative value)
+ *             Failure: FAIL (-1) (negative value)
+ *
+ * Programmer: Jacob Smith
+ *             2018 August 17
+ *
+ *-----------------------------------------------------------------------------
+ */
+herr_t
+H5O__apply_ohdr(H5F_t *f, H5O_t *oh, hid_t ocpl_id, size_t size_hint, size_t initial_rc, H5O_loc_t *loc_out)
+{
+    haddr_t         oh_addr;
+    size_t          oh_size;
+    H5P_genplist_t *oc_plist     = NULL;
+    unsigned        insert_flags = H5AC__NO_FLAGS_SET;
+    herr_t          ret_value    = SUCCEED;
 
-    if(H5O_set_version(f, oh, oh_flags, store_msg_crt_idx) < 0)
-        HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set version of objecdt header")
+    FUNC_ENTER_NOAPI(FAIL)
+
+    HDassert(f);
+    HDassert(loc_out);
+    HDassert(oh);
+    HDassert(TRUE == H5P_isa_class(ocpl_id, H5P_OBJECT_CREATE));
+
+    /* Allocate at least a reasonable size for the object header */
+    size_hint = H5O_ALIGN_F(f, MAX(H5O_MIN_SIZE, size_hint));
 
     oh->sizeof_size = H5F_SIZEOF_SIZE(f);
     oh->sizeof_addr = H5F_SIZEOF_ADDR(f);
-    oh->swmr_write = !!(H5F_INTENT(f) & H5F_ACC_SWMR_WRITE);
+    oh->swmr_write = !!(H5F_INTENT(f) & H5F_ACC_SWMR_WRITE); /* funky cast */
+
 #ifdef H5O_ENABLE_BAD_MESG_COUNT
     /* Check whether the "bad message count" property is set */
-    if(H5P_exist_plist(oc_plist, H5O_BAD_MESG_COUNT_NAME) > 0) {
-        /* Retrieve bad message count flag */
+    if(0 < H5P_exist_plist(oc_plist, H5O_BAD_MESG_COUNT_NAME))
+        /* Get bad message count flag -- from property list */
         if(H5P_get(oc_plist, H5O_BAD_MESG_COUNT_NAME, &oh->store_bad_mesg_count) < 0)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't get bad message count flag")
-    }
 #endif /* H5O_ENABLE_BAD_MESG_COUNT */
 
     /* Create object header proxy if doing SWMR writes */
     if(oh->swmr_write) {
-        /* Create virtual entry, for use as proxy */
-        if(NULL == (oh->proxy = H5AC_proxy_entry_create()))
+        oh->proxy = H5AC_proxy_entry_create();
+        if(NULL == oh->proxy)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "can't create object header proxy")
-    }
-    else
+    } else {
         oh->proxy = NULL;
+    }
 
-    /* Set initial status flags */
-    oh->flags = oh_flags;
+    oc_plist = (H5P_genplist_t *)H5I_object(ocpl_id);
+    if(NULL == oc_plist)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a property list")
 
     /* Initialize version-specific fields */
     if(oh->version > H5O_VERSION_1) {
-        /* Initialize all time fields with current time, if we are storing them */
+        /* Initialize all time fields */
         if(oh->flags & H5O_HDR_STORE_TIMES)
             oh->atime = oh->mtime = oh->ctime = oh->btime = H5_now();
         else
             oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
 
-        /* Make certain attribute creation order tracking is enabled if
-         *      attributes can be shared in this file.
-         */
-        if(store_msg_crt_idx)
+        if(H5F_STORE_MSG_CRT_IDX(f))
+            /* flag to record message creation indices */
             oh->flags |= H5O_HDR_ATTR_CRT_ORDER_TRACKED;
 
-        /* Retrieve attribute storage phase change values from property list */
+        /* Get attribute storage phase change values -- from property list */
         if(H5P_get(oc_plist, H5O_CRT_ATTR_MAX_COMPACT_NAME, &oh->max_compact) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get max. # of compact attributes")
         if(H5P_get(oc_plist, H5O_CRT_ATTR_MIN_DENSE_NAME, &oh->min_dense) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get min. # of dense attributes")
 
         /* Check for non-default attribute storage phase change values */
-        if(oh->max_compact != H5O_CRT_ATTR_MAX_COMPACT_DEF || oh->min_dense != H5O_CRT_ATTR_MIN_DENSE_DEF)
+        if(H5O_CRT_ATTR_MAX_COMPACT_DEF != oh->max_compact  || H5O_CRT_ATTR_MIN_DENSE_DEF != oh->min_dense )
             oh->flags |= H5O_HDR_ATTR_STORE_PHASE_CHANGE;
 
         /* Determine correct value for chunk #0 size bits */
@@ -383,23 +466,25 @@ H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc, hid_t ocpl_id,
             oh->flags |= H5O_HDR_CHUNK0_4;
         else if(size_hint > 255)
             oh->flags |= H5O_HDR_CHUNK0_2;
-    } /* end if */
-    else {
+    } else {
         /* Reset unused time fields */
         oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
-    } /* end else */
+    } /* end if/else header version >1 */
 
     /* Compute total size of initial object header */
     /* (i.e. object header prefix and first chunk) */
     oh_size = (size_t)H5O_SIZEOF_HDR(oh) + size_hint;
 
     /* Allocate disk space for header and first chunk */
-    if(HADDR_UNDEF == (oh_addr = H5MF_alloc(f, H5FD_MEM_OHDR, (hsize_t)oh_size)))
+    oh_addr = H5MF_alloc(f, H5FD_MEM_OHDR, (hsize_t)oh_size);
+    if(HADDR_UNDEF == oh_addr)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for object header")
 
     /* Create the chunk list */
-    oh->nchunks = oh->alloc_nchunks = 1;
-    if(NULL == (oh->chunk = H5FL_SEQ_MALLOC(H5O_chunk_t, (size_t)oh->alloc_nchunks)))
+    oh->nchunks = 1;
+    oh->alloc_nchunks = 1;
+    oh->chunk = H5FL_SEQ_MALLOC(H5O_chunk_t, (size_t)oh->alloc_nchunks);
+    if(NULL == oh->chunk)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
     /* Initialize the first chunk */
@@ -409,25 +494,27 @@ H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc, hid_t ocpl_id,
 
     /* Allocate enough space for the first chunk */
     /* (including space for serializing the object header prefix */
-    if(NULL == (oh->chunk[0].image = H5FL_BLK_CALLOC(chunk_image, oh_size)))
+    oh->chunk[0].image = H5FL_BLK_CALLOC(chunk_image, oh_size);
+    if(NULL == oh->chunk[0].image)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
     oh->chunk[0].chunk_proxy = NULL;
 
     /* Put magic # for object header in first chunk */
-    if(oh->version > H5O_VERSION_1)
+    if(H5O_VERSION_1 < oh->version)
         HDmemcpy(oh->chunk[0].image, H5O_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC);
 
     /* Create the message list */
     oh->nmesgs = 1;
     oh->alloc_nmesgs = H5O_NMESGS;
-    if(NULL == (oh->mesg = H5FL_SEQ_CALLOC(H5O_mesg_t, oh->alloc_nmesgs)))
+    oh->mesg = H5FL_SEQ_CALLOC(H5O_mesg_t, oh->alloc_nmesgs);
+    if(NULL == oh->mesg)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
-    /* Initialize the initial "null" message, covering the entire first chunk */
+    /* Initialize the initial "null" message; covers the entire first chunk */
     oh->mesg[0].type = H5O_MSG_NULL;
     oh->mesg[0].dirty = TRUE;
     oh->mesg[0].native = NULL;
-    oh->mesg[0].raw = oh->chunk[0].image + (H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)) + H5O_SIZEOF_MSGHDR_OH(oh);
+    oh->mesg[0].raw = oh->chunk[0].image + H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh) + H5O_SIZEOF_MSGHDR_OH(oh);
     oh->mesg[0].raw_size = size_hint - (size_t)H5O_SIZEOF_MSGHDR_OH(oh);
     oh->mesg[0].chunkno = 0;
 
@@ -452,20 +539,15 @@ H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc, hid_t ocpl_id,
     H5_END_TAG
 
     /* Set up object location */
-    loc->file = f;
-    loc->addr = oh_addr;
+    loc_out->file = f;
+    loc_out->addr = oh_addr;
 
-    /* Open it */
-    if(H5O_open(loc) < 0)
+    if(H5O_open(loc_out) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open object header")
 
 done:
-    if(ret_value < 0 && oh)
-        if(H5O__free(oh) < 0)
-            HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to destroy object header data")
-
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5O_create() */
+    FUNC_LEAVE_NOAPI(ret_value);
+} /* H5O__apply_ohdr() */
 
 
 /*-------------------------------------------------------------------------
@@ -2420,6 +2502,63 @@ H5O_get_oh_addr(const H5O_t *oh)
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_get_oh_flags
+ *
+ * Programmer:	Jacob Smith
+ *		2018 August 17
+ *
+ *-------------------------------------------------------------------------
+ */
+uint8_t
+H5O_get_oh_flags(const H5O_t *oh)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    HDassert(oh);
+    FUNC_LEAVE_NOAPI(oh->flags); /* flags can be 0 */
+} /* H5O_get_oh_flags() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_get_oh_mtime
+ *
+ * Purpose:	Retrieve an object's modification time. Assumes that the
+ *              caller has verified that accessing this variable is appropriate
+ *              to the header in question.
+ *
+ * Programmer:	Jacob Smith
+ *		2018 August 17
+ *
+ *-------------------------------------------------------------------------
+ */
+time_t
+H5O_get_oh_mtime(const H5O_t *oh)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    HDassert(oh);
+    HDassert(oh->mtime);
+    FUNC_LEAVE_NOAPI(oh->mtime);
+} /* H5O_get_oh_mtime() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_get_oh_version
+ *
+ * Programmer:	Jacob Smith
+ *		2018 August 17
+ *
+ *-------------------------------------------------------------------------
+ */
+uint8_t
+H5O_get_oh_version(const H5O_t *oh)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    HDassert(oh);
+    HDassert(oh->version);
+    FUNC_LEAVE_NOAPI(oh->version);
+} /* H5O_get_oh_version() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_get_rc_and_type
  *
  * Purpose:	Retrieve an object's reference count and type
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 7ed9e26..e0926e2 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -121,8 +121,14 @@ typedef struct H5O_mesg_t H5O_mesg_t;
 /* If the module using this macro is allowed access to the private variables, access them directly */
 #ifdef H5O_MODULE
 #define H5O_OH_GET_ADDR(O)    ((O)->chunk[0].addr)
+#define H5O_OH_GET_VERSION(O) ((O)->version)
+#define H5O_OH_GET_FLAGS(O)   ((O)->flags)
+#define H5O_OH_GET_MTIME(O)   ((O)->mtime)
 #else /* H5O_MODULE */
 #define H5O_OH_GET_ADDR(O)    (H5O_get_oh_addr(O))
+#define H5O_OH_GET_VERSION(O) (H5O_get_oh_version(O))
+#define H5O_OH_GET_FLAGS(O)   (H5O_get_oh_flags(O))
+#define H5O_OH_GET_MTIME(O)   (H5O_get_oh_mtime(O))
 #endif /* H5O_MODULE */
 
 /* Set the fields in a shared message structure */
@@ -865,6 +871,9 @@ struct H5P_genplist_t;
 H5_DLL herr_t H5O_init(void);
 H5_DLL herr_t H5O_create(H5F_t *f, size_t size_hint, size_t initial_rc,
     hid_t ocpl_id, H5O_loc_t *loc/*out*/);
+H5_DLL H5O_t *H5O__create_ohdr(H5F_t *f, hid_t ocpl_id);
+H5_DLL herr_t H5O__apply_ohdr(H5F_t *f, H5O_t *oh, hid_t ocpl_id,
+    size_t size_hint, size_t initial_rc, H5O_loc_t *loc_out);
 H5_DLL herr_t H5O_open(H5O_loc_t *loc);
 H5_DLL void *H5O_open_by_idx(const H5G_loc_t *loc, const char *name,
     H5_index_t idx_type, H5_iter_order_t order, hsize_t n, H5I_type_t *opened_type/*out*/);
@@ -891,6 +900,9 @@ H5_DLL void *H5O_open_name(const H5G_loc_t *loc, const char *name, H5I_type_t *o
 H5_DLL herr_t H5O_get_nlinks(const H5O_loc_t *loc, hsize_t *nlinks);
 H5_DLL void *H5O_obj_create(H5F_t *f, H5O_type_t obj_type, void *crt_info, H5G_loc_t *obj_loc);
 H5_DLL haddr_t H5O_get_oh_addr(const H5O_t *oh);
+H5_DLL uint8_t H5O_get_oh_flags(const H5O_t *oh);
+H5_DLL time_t H5O_get_oh_mtime(const H5O_t *oh);
+H5_DLL uint8_t H5O_get_oh_version(const H5O_t *oh);
 H5_DLL herr_t H5O_get_rc_and_type(const H5O_loc_t *oloc, unsigned *rc, H5O_type_t *otype);
 H5_DLL H5AC_proxy_entry_t *H5O_get_proxy(const H5O_t *oh);
 
diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index a5a16bb..b85f105 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -117,6 +117,11 @@
 #define H5D_CRT_EXT_FILE_LIST_COPY H5P__dcrt_ext_file_list_copy
 #define H5D_CRT_EXT_FILE_LIST_CMP  H5P__dcrt_ext_file_list_cmp
 #define H5D_CRT_EXT_FILE_LIST_CLOSE H5P__dcrt_ext_file_list_close
+/* Definitions for dataset object header minimization */
+#define H5D_CRT_MIN_DSET_HDR_SIZE_SIZE sizeof(hbool_t)
+#define H5D_CRT_MIN_DSET_HDR_SIZE_DEF  FALSE
+#define H5D_CRT_MIN_DSET_HDR_SIZE_ENC  H5P__encode_hbool_t
+#define H5D_CRT_MIN_DSET_HDR_SIZE_DEC  H5P__decode_hbool_t
 
 
 /******************/
@@ -209,6 +214,7 @@ static const H5O_layout_t H5D_def_layout_g = H5D_CRT_LAYOUT_DEF;        /* Defau
 static const H5O_fill_t H5D_def_fill_g = H5D_CRT_FILL_VALUE_DEF;        /* Default fill value */
 static const unsigned H5D_def_alloc_time_state_g = H5D_CRT_ALLOC_TIME_STATE_DEF;  /* Default allocation time state */
 static const H5O_efl_t H5D_def_efl_g = H5D_CRT_EXT_FILE_LIST_DEF;                 /* Default external file list */
+static const unsigned H5O_ohdr_min_g = H5D_CRT_MIN_DSET_HDR_SIZE_DEF; /* Default object header minimization */
 
 /* Defaults for each type of layout */
 #ifdef H5_HAVE_C99_DESIGNATED_INITIALIZER
@@ -271,6 +277,12 @@ H5P__dcrt_reg_prop(H5P_genclass_t *pclass)
             H5D_CRT_EXT_FILE_LIST_DEL, H5D_CRT_EXT_FILE_LIST_COPY, H5D_CRT_EXT_FILE_LIST_CMP, H5D_CRT_EXT_FILE_LIST_CLOSE) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
 
+    /* Register the object header minimization property */
+    if(H5P__register_real(pclass, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, H5D_CRT_MIN_DSET_HDR_SIZE_SIZE, &H5O_ohdr_min_g,
+            NULL, NULL, NULL, H5D_CRT_MIN_DSET_HDR_SIZE_ENC, H5D_CRT_MIN_DSET_HDR_SIZE_DEC,
+            NULL, NULL, NULL, NULL) < 0)
+       HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
     /* Register the type ID property*/
     if(H5P__register_real(pclass, H5VL_PROP_DSET_TYPE_ID, sizeof(hid_t), &type_id, 
                          NULL, NULL, NULL, NULL, NULL, NULL, NULL, H5P_ignore_cmp, NULL) < 0)
@@ -3749,3 +3761,95 @@ done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_fill_time() */
 
+
+/*-----------------------------------------------------------------------------
+ * Function: H5Pget_dset_no_attrs_hint
+ *
+ * Purpose:
+ *
+ *     Access the flag for whether or not datasets created by the given dcpl
+ *     will be created with a "minimized" object header.
+ *
+ * Return:
+ *
+ *     Failure: Negative value (FAIL)
+ *     Success: Non-negative value (SUCCEED)
+ *
+ * Programmer: Jacob Smith
+ *             2018 August 14
+ *
+ * Modifications: None.
+ *
+ *-----------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_dset_no_attrs_hint(hid_t dcpl_id, hbool_t *minimize)
+{
+    hbool_t         setting   = FALSE;
+    H5P_genplist_t *plist     = NULL;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "i*b", dcpl_id, minimize);
+
+    if(NULL == minimize)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "receiving pointer cannot be NULL")
+
+    plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE);
+    if(NULL == plist)
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    if(H5P_peek(plist, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, &setting) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get dset oh minimize flag value")
+
+    *minimize = setting;
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Pget_dset_no_attrs_hint() */
+
+
+/*-----------------------------------------------------------------------------
+ * Function: H5Pset_dset_no_attrs_hint
+ *
+ * Purpose:
+ *
+ *     Set the dcpl to minimize (or explicitly to not minimized) dataset object
+ *     headers upon creation.
+ *
+ * Return:
+ *
+ *     Failure: Negative value (FAIL)
+ *     Success: Non-negative value (SUCCEED)
+ *
+ * Programmer: Jacob Smith
+ *             2018 August 14
+ *
+ * Modifications: None.
+ *
+ *-----------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_dset_no_attrs_hint(hid_t dcpl_id, hbool_t minimize)
+{
+    H5P_genplist_t *plist     = NULL;
+    hbool_t         prev_set  = FALSE;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ib", dcpl_id, minimize);
+
+    plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE);
+    if(NULL == plist)
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    if(H5P_peek(plist, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, &prev_set) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get extant dset oh minimize flag value")
+
+    if(H5P_poke(plist, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, &minimize) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't get dset oh minimize flag value")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Pset_dset_no_attrs_hint() */
+
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 86c6687..2f094ea 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -412,6 +412,8 @@ H5_DLL herr_t H5Pget_alloc_time(hid_t plist_id, H5D_alloc_time_t
 H5_DLL herr_t H5Pset_fill_time(hid_t plist_id, H5D_fill_time_t fill_time);
 H5_DLL herr_t H5Pget_fill_time(hid_t plist_id, H5D_fill_time_t
     *fill_time/*out*/);
+H5_DLL herr_t H5Pget_dset_no_attrs_hint(hid_t dcpl_id, hbool_t *minimize);
+H5_DLL herr_t H5Pset_dset_no_attrs_hint(hid_t dcpl_id, hbool_t minimize);
 
 /* Dataset access property list (DAPL) routines */
 H5_DLL herr_t H5Pset_chunk_cache(hid_t dapl_id, size_t rdcc_nslots,
diff --git a/src/H5VL.c b/src/H5VL.c
index bf1201f..88d3d70 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -11,7 +11,7 @@
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
 /*
- * Purpose:	The Virtual Object Layer as described in documentation.
+ * Purpose:     The Virtual Object Layer as described in documentation.
  *              The pupose is to provide an abstraction on how to access the
  *              underlying HDF5 container, whether in a local file with
  *              a specific file format, or remotely on other machines, etc...
@@ -486,14 +486,11 @@ done:
 /*---------------------------------------------------------------------------
  * Function:    H5VLcmp_connector_cls
  *
- * Purpose:     Compares two connector classes
+ * Purpose:     Compares two connector classes (based on their value field)
  *
- * Return:      Success:    Non-negative, with *cmp set to positive if
- *		connector_id1 is greater than connector_id2, negative if connector_id2
- *		is greater than connector_id1 and zero if connector_id1 and connector_id2
- *		are equal.
+ * Return:      Success:    Non-negative, *cmp set to a value like strcmp
  *
- *              Failure:    Negative
+ *              Failure:    Negative, *cmp unset
  *
  *---------------------------------------------------------------------------
  */
diff --git a/src/H5VLint.c b/src/H5VLint.c
index d51be0c..8695a80 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -881,7 +881,7 @@ done:
  *
  * Return:      Positive if VALUE1 is greater than VALUE2, negative if
  *              VALUE2 is greater than VALUE1 and zero if VALUE1 and
- *              VALUE2 are equal.
+ *              VALUE2 are equal (like strcmp).
  *
  *-------------------------------------------------------------------------
  */
diff --git a/src/H5VLnative.h b/src/H5VLnative.h
index 916151b..1a3007a 100644
--- a/src/H5VLnative.h
+++ b/src/H5VLnative.h
@@ -66,6 +66,8 @@ typedef int H5VL_native_file_optional_t;
 #define H5VL_NATIVE_FILE_GET_EOA                        22  /* H5Fget_eoa                           */
 #define H5VL_NATIVE_FILE_INCR_FILESIZE                  23  /* H5Fincrement_filesize                */
 #define H5VL_NATIVE_FILE_SET_LIBVER_BOUNDS              24  /* H5Fset_latest_format/libver_bounds   */
+#define H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG         25  /* H5Fget_dset_no_attrs_hint            */
+#define H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG         26  /* H5Fset_dset_no_attrs_hint            */
 
 /* Typedef and values for native VOL connector group optional VOL operations */
 typedef int H5VL_native_group_optional_t;
diff --git a/src/H5VLnative_file.c b/src/H5VLnative_file.c
index cc21a22..e7f27e1 100644
--- a/src/H5VLnative_file.c
+++ b/src/H5VLnative_file.c
@@ -377,6 +377,8 @@ H5VL__native_file_specific(void *obj, H5VL_file_specific_t specific_type,
                 break;
             }
 
+
+
         default:
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "invalid specific operation")
     } /* end switch */
@@ -750,6 +752,23 @@ H5VL__native_file_optional(void *obj, hid_t H5_ATTR_UNUSED dxpl_id, void H5_ATTR
                 break;
             }
 
+        /* H5Fget_dset_no_attrs_hint */
+        case H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG:
+            {
+                hbool_t *minimize = va_arg(arguments, hbool_t *);
+                *minimize = H5F_GET_MIN_DSET_OHDR(f);
+                break;
+            }
+
+        /* H5Fset_dset_no_attrs_hint */
+        case H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG:
+            {
+                int minimize = va_arg(arguments, int);
+                if(H5F_set_min_dset_ohdr(f, (hbool_t)minimize) < 0)
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTSET, FAIL, "cannot set file's dataset object header minimization flag")
+                break;
+            }
+
         default:
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "invalid optional operation")
     } /* end switch */
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index 22cf12b..5de36c8 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -115,7 +115,7 @@ typedef enum H5VL_file_get_t {
     H5VL_FILE_GET_INTENT,	            /* file intent           		*/
     H5VL_FILE_GET_NAME,	                    /* file name             		*/
     H5VL_FILE_GET_OBJ_COUNT,	            /* object count in file	       	*/
-    H5VL_FILE_GET_OBJ_IDS 	            /* object ids in file     		*/
+    H5VL_FILE_GET_OBJ_IDS	            /* object ids in file     		*/
 } H5VL_file_get_t;
 
 /* types for file SPECIFIC callback */
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index ed6bacc..69afb85 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -133,7 +133,7 @@ if (BUILD_SHARED_LIBS)
   # Define VOL Plugin Test Sources
   #-----------------------------------------------------------------------------
   set (VOL_PLUGIN_LIBS
-      echo_vol
+      null_vol_connector
   )
 
   foreach (vol_lib ${VOL_PLUGIN_LIBS})
diff --git a/test/CMakeTests.cmake b/test/CMakeTests.cmake
index 26faba6..9816543 100644
--- a/test/CMakeTests.cmake
+++ b/test/CMakeTests.cmake
@@ -359,6 +359,9 @@ set (test_CLEANFILES
     lheap.h5
     fheap.h5
     ohdr.h5
+    ohdr_min_a.h5
+    ohdr_min_b.h5
+    min_dset_ohdr_testfile.h5
     stab.h5
     extern_*.h5
     extern_*.raw
diff --git a/test/Makefile.am b/test/Makefile.am
index 1526eca..1a232ab 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -41,8 +41,8 @@ SCRIPT_DEPEND = error_test$(EXEEXT) err_compat$(EXEEXT) links_env$(EXEEXT) filen
     swmr_sparse_reader$(EXEEXT) swmr_sparse_writer$(EXEEXT) swmr_start_write$(EXEEXT) \
     vds_swmr_gen$(EXEEXT) vds_swmr_reader$(EXEEXT) vds_swmr_writer$(EXEEXT)
 if HAVE_SHARED_CONDITIONAL
-  TEST_SCRIPT += test_filter_plugin.sh
-  SCRIPT_DEPEND += filter_plugin$(EXEEXT)
+  TEST_SCRIPT += test_filter_plugin.sh test_vol_plugin.sh
+  SCRIPT_DEPEND += filter_plugin$(EXEEXT) vol_plugin$(EXEEXT)
 endif
 
 check_SCRIPTS = $(TEST_SCRIPT)
@@ -52,8 +52,8 @@ check_SCRIPTS = $(TEST_SCRIPT)
 # As an exception, long-running tests should occur earlier in the list.
 # This gives them more time to run when tests are executing in parallel.
 TEST_PROG= testhdf5 \
-           cache cache_api cache_image cache_tagging lheap ohdr stab gheap \
-           evict_on_close farray earray btree2 fheap \
+           cache cache_api cache_image cache_tagging lheap ohdr \
+           stab gheap evict_on_close farray earray btree2 fheap \
            pool accum hyperslab istore bittests dt_arith page_buffer \
            dtypes dsets cmpd_dset filter_fail extend direct_chunk external efc \
            objcopy links unlink twriteorder big mtime fillval mount \
@@ -83,7 +83,7 @@ check_PROGRAMS=$(TEST_PROG) error_test err_compat tcheck_version \
     swmr_remove_writer swmr_addrem_writer swmr_sparse_reader swmr_sparse_writer \
     swmr_check_compat_vfd vds_swmr_gen vds_swmr_reader vds_swmr_writer
 if HAVE_SHARED_CONDITIONAL
-  check_PROGRAMS+= filter_plugin
+  check_PROGRAMS+= filter_plugin vol_plugin
 endif
 
 # These programs generate test files for the tests.  They don't need to be
@@ -106,9 +106,7 @@ if HAVE_SHARED_CONDITIONAL
   # The libh5test library provides common support code for the tests.
   # The filter_plugin* libraries are for use in filter_plugin.c.
   # Build them as shared libraries if that option was enabled in configure.
-  #
-  # echo_vol is used for testing VOL plugin functionality.
-  noinst_LTLIBRARIES=libh5test.la libfilter_plugin1_dsets.la libfilter_plugin2_dsets.la libfilter_plugin3_dsets.la libfilter_plugin4_groups.la echo_vol.la
+  noinst_LTLIBRARIES=libh5test.la libfilter_plugin1_dsets.la libfilter_plugin2_dsets.la libfilter_plugin3_dsets.la libfilter_plugin4_groups.la libnull_vol_connector.la
   libfilter_plugin1_dsets_la_SOURCES=filter_plugin1_dsets.c
   libfilter_plugin2_dsets_la_SOURCES=filter_plugin2_dsets.c
   libfilter_plugin3_dsets_la_SOURCES=filter_plugin3_dsets.c
@@ -121,8 +119,10 @@ if HAVE_SHARED_CONDITIONAL
   libfilter_plugin4_groups_la_LIBADD=$(LIBHDF5)
 
   # VOL plugin test libraries
-  echo_vol_la_SOURCES=echo_vol.c
-  echo_vol_la_LDFLAGS=$(AM_LDFLAGS) -avoid-version -module -shared -export-dynamic -rpath /nowhere
+  #
+  # null_vol_connector is used for testing basic VOL plugin functionality.
+  libnull_vol_connector_la_SOURCES=null_vol_connector.c
+  libnull_vol_connector_la_LDFLAGS=$(AM_LDFLAGS) -avoid-version -module -shared -export-dynamic -rpath /nowhere
 
 else
   # The libh5test library provides common support code for the tests.
@@ -177,6 +177,7 @@ CHECK_CLEANFILES+=accum.h5 cmpd_dset.h5 compact_dataset.h5 dataset.h5 dset_offse
     extend.h5 istore.h5 extlinks*.h5 frspace.h5 links*.h5 \
     sys_file1 tfile[1-7].h5 th5s[1-4].h5 lheap.h5 fheap.h5 ohdr.h5 \
     stab.h5 extern_[1-5].h5 extern_[1-4][rw].raw gheap[0-4].h5 \
+    ohdr_min_a.h5 ohdr_min_b.h5 min_dset_ohdr_testfile.h5\
     dt_arith[1-2] links.h5 links[0-6]*.h5 extlinks[0-15].h5 tmp \
     big.data big[0-9][0-9][0-9][0-9][0-9].h5  \
     stdio.h5 sec2.h5 dtypes[0-9].h5 dtypes1[0].h5 dt_arith[1-2].h5 tattr.h5 \
@@ -220,6 +221,7 @@ use_disable_mdc_flushes_SOURCES=use_disable_mdc_flushes.c
 
 # Temporary files.
 DISTCLEANFILES=testerror.sh testlibinfo.sh testcheck_version.sh testlinks_env.sh test_filter_plugin.sh \
-    testswmr.sh testvdsswmr.sh test_usecases.sh testflushrefresh.sh test_filenotclosed.sh
+    testswmr.sh testvdsswmr.sh test_usecases.sh testflushrefresh.sh test_filenotclosed.sh \
+	test_vol_plugin.sh
 
 include $(top_srcdir)/config/conclude.am
diff --git a/test/dsets.c b/test/dsets.c
index 5cd376a..e63878c 100644
--- a/test/dsets.c
+++ b/test/dsets.c
@@ -86,6 +86,9 @@ const char *FILENAME[] = {
     NULL
 };
 
+#define OHMIN_FILENAME_A "ohdr_min_a"
+
+
 #define FILENAME_BUF_SIZE       1024
 #define KB                      1024
 
@@ -338,7 +341,7 @@ filter_count(unsigned int flags, size_t H5_ATTR_UNUSED cd_nelmts,
         count_nbytes_written += nbytes;
 
     return nbytes;
-}
+} /* end filter_count() */
 
 
 /*-------------------------------------------------------------------------
@@ -481,11 +484,11 @@ test_create(hid_t file)
     if(H5Dclose(dataset) < 0) goto error;
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
  error:
-    return -1;
-}
+    return FAIL;
+} /* end test_create() */
 
 
 /*-------------------------------------------------------------------------
@@ -605,7 +608,7 @@ test_simple_io(const char *env_h5_drvr, hid_t fapl)
         puts("    Current VFD doesn't support continuous address space");
     } /* end else */
 
-    return 0;
+    return SUCCEED;
 
 error:
     if(space > 0)
@@ -620,8 +623,8 @@ error:
         HDclose(f);
     if(tconv_buf)
         HDfree(tconv_buf);
-    return -1;
-}
+    return FAIL;
+} /* end test_simple_io() */
 
 
 /*-------------------------------------------------------------------------
@@ -713,7 +716,7 @@ test_userblock_offset(const char *env_h5_drvr, hid_t fapl, hbool_t new_format)
         puts("    Current VFD doesn't support continuous address space");
     } /* end else */
 
-    return 0;
+    return SUCCEED;
 
 error:
     if(space > 0)
@@ -726,8 +729,8 @@ error:
         if(H5Fclose(file) < 0) TEST_ERROR
     if(f > 0)
         HDclose(f);
-    return -1;
-}
+    return FAIL;
+} /* end test_userblock_offset() */
 
 
 /*-------------------------------------------------------------------------
@@ -826,7 +829,7 @@ test_compact_io(hid_t fapl)
      **************************************/
 
     /* Create a copy of file access property list */
-    if((new_fapl = new_fapl = h5_fileaccess()) < 0) TEST_ERROR
+    if((new_fapl = h5_fileaccess()) < 0) TEST_ERROR
 
     /* Loop through all the combinations of low/high library format bounds,
        skipping invalid combinations.
@@ -907,7 +910,7 @@ test_compact_io(hid_t fapl)
     if(H5Pclose(plist) < 0) TEST_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
  error:
     H5E_BEGIN_TRY {
@@ -919,8 +922,8 @@ test_compact_io(hid_t fapl)
         H5Fclose(verfile);
     } H5E_END_TRY;
 
-    return -1;
-}
+    return FAIL;
+} /* end test_compact_io() */
 
 
 /*-------------------------------------------------------------------------
@@ -1056,7 +1059,7 @@ test_max_compact(hid_t fapl)
          FAIL_STACK_ERROR
 
      PASSED();
-     return 0;
+     return SUCCEED;
 
 error:
     if(wbuf)
@@ -1072,7 +1075,7 @@ error:
         H5Fclose(file);
     } H5E_END_TRY;
 
-     return -1;
+     return FAIL;
 } /* end test_max_compact() */
 
 
@@ -1181,7 +1184,7 @@ test_layout_extend(hid_t fapl)
     if(H5Fclose(fid) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -1195,7 +1198,7 @@ error:
         H5Fclose(fid);
     } H5E_END_TRY;
 
-     return -1;
+     return FAIL;
 } /* end test_layout_extend() */
 
 
@@ -1331,7 +1334,7 @@ test_conv_buffer(hid_t fid)
   HDfree(cf);
   HDfree(cfrR);
   puts(" PASSED");
-  return 0;
+  return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -1347,8 +1350,8 @@ error:
         H5Dclose(dataset);
     } H5E_END_TRY;
 
-  return -1;
-}
+  return FAIL;
+} /* end test_conv_buffer() */
 
 
 /*-------------------------------------------------------------------------
@@ -1418,7 +1421,7 @@ test_tconv(hid_t file)
     HDfree(in);
 
     puts(" PASSED");
-    return 0;
+    return SUCCEED;
 
 error:
     if(out)
@@ -1431,8 +1434,8 @@ error:
         H5Sclose(space);
     } H5E_END_TRY;
 
-    return -1;
-}
+    return FAIL;
+} /* end test_tconv() */
 
 /* This message derives from H5Z */
 const H5Z_class2_t H5Z_BOGUS[1] = {{
@@ -1465,7 +1468,7 @@ can_apply_bogus(hid_t H5_ATTR_UNUSED dcpl_id, hid_t type_id, hid_t H5_ATTR_UNUSE
         return 1;
     else
         return -1;
-}
+} /* end can_apply_bogus() */
 
 
 /*-------------------------------------------------------------------------
@@ -1483,7 +1486,7 @@ filter_bogus(unsigned int H5_ATTR_UNUSED flags, size_t H5_ATTR_UNUSED cd_nelmts,
       size_t H5_ATTR_UNUSED *buf_size, void H5_ATTR_UNUSED **buf)
 {
     return nbytes;
-}
+} /* end filter_bogus() */
 
 
 /*-------------------------------------------------------------------------
@@ -1583,7 +1586,7 @@ filter_bogus2(unsigned int flags, size_t cd_nelmts,
     /* Filter is "no op" */
     else
         return(nbytes);
-}
+} /* end filter_bogus2() */
 
 
 /*-------------------------------------------------------------------------
@@ -1601,7 +1604,7 @@ filter_bogus3(unsigned int H5_ATTR_UNUSED flags, size_t H5_ATTR_UNUSED cd_nelmts
       size_t H5_ATTR_UNUSED *buf_size, void H5_ATTR_UNUSED **buf)
 {
     return 0;
-}
+} /* end filter_bogus3() */
 
 /* This message derives from H5Z */
 const H5Z_class2_t H5Z_CORRUPT[1] = {{
@@ -1690,7 +1693,7 @@ filter_cb_cont(H5Z_filter_t filter, void H5_ATTR_UNUSED *buf, size_t H5_ATTR_UNU
        return H5Z_CB_CONT;
     else
         return H5Z_CB_FAIL;
-}
+} /* end filter_cb_cont() */
 
 
 /*-------------------------------------------------------------------------
@@ -1709,7 +1712,7 @@ filter_cb_fail(H5Z_filter_t filter, void H5_ATTR_UNUSED *buf, size_t H5_ATTR_UNU
        return H5Z_CB_FAIL;
     else
        return H5Z_CB_CONT;
-}
+} /* end filter_cb_fail() */
 
 
 /*-------------------------------------------------------------------------
@@ -2052,13 +2055,13 @@ test_filter_internal(hid_t fid, const char *name, hid_t dcpl, int if_fletcher32,
     if(H5Pclose (write_dxpl) < 0) goto error;
     HDfree (tconv_buf);
 
-    return(0);
+    return SUCCEED;
 
 error:
     if(tconv_buf)
         HDfree (tconv_buf);
-    return -1;
-}
+    return FAIL;
+} /* end test_filter_internal() */
 
 /*-------------------------------------------------------------------------
  * Function:  test_filter_noencoder
@@ -2160,7 +2163,7 @@ test_filter_noencoder(const char *dset_name)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5_FAILED();
@@ -2175,8 +2178,8 @@ error:
     if(file_id != -1)
         H5Fclose(file_id);
 
-    return -1;
-}
+    return FAIL;
+} /* end test_filter_noencoder() */
 #endif /* H5_HAVE_FILTER_SZIP */
 
 /*-------------------------------------------------------------------------
@@ -2242,11 +2245,11 @@ test_get_filter_info(void)
   if(err >= 0) TEST_ERROR
 
   PASSED();
-  return 0;
+  return SUCCEED;
 
 error:
-  return -1;
-}
+  return FAIL;
+} /* end test_get_filter_info() */
 
 /*-------------------------------------------------------------------------
  * Function:  test_filters
@@ -2517,11 +2520,11 @@ H5_ATTR_UNUSED
     SKIPPED();
     puts("    szip filter not enabled");
 #endif /* H5_HAVE_FILTER_SZIP */
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_filters() */
 
 
 /*-------------------------------------------------------------------------
@@ -2856,11 +2859,11 @@ test_onebyte_shuffle(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_onebyte_shuffle() */
 
 
 /*-------------------------------------------------------------------------
@@ -2974,11 +2977,11 @@ test_nbit_int(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_int() */
 
 
 /*-------------------------------------------------------------------------
@@ -3092,11 +3095,11 @@ test_nbit_float(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_float() */
 
 
 /*-------------------------------------------------------------------------
@@ -3224,11 +3227,11 @@ test_nbit_double(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_double() */
 
 
 /*-------------------------------------------------------------------------
@@ -3351,11 +3354,11 @@ test_nbit_array(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_array() */
 
 
 /*-------------------------------------------------------------------------
@@ -3568,11 +3571,11 @@ test_nbit_compound(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_compound() */
 
 
 /*-------------------------------------------------------------------------
@@ -3913,11 +3916,11 @@ out:
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_compound_2() */
 
 
 /*-------------------------------------------------------------------------
@@ -4093,11 +4096,11 @@ test_nbit_compound_3(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_compound_3() */
 
 
 /*-------------------------------------------------------------------------
@@ -4261,10 +4264,10 @@ test_nbit_int_size(hid_t file)
 
     PASSED();
 
-   return 0;
+   return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_int_size() */
 
 
 /*-------------------------------------------------------------------------
@@ -4458,10 +4461,10 @@ test_nbit_flt_size(hid_t file)
 
     PASSED();
 
-   return 0;
+   return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_nbit_flt_size() */
 
 /*-------------------------------------------------------------------------
  * Function:    test_scaleoffset_int
@@ -4569,10 +4572,10 @@ test_scaleoffset_int(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_int() */
 
 
 /*-------------------------------------------------------------------------
@@ -4697,10 +4700,10 @@ test_scaleoffset_int_2(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_int_2() */
 
 
 /*-------------------------------------------------------------------------
@@ -4810,10 +4813,10 @@ test_scaleoffset_float(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_float() */
 
 
 /*-------------------------------------------------------------------------
@@ -4939,10 +4942,10 @@ test_scaleoffset_float_2(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_float_2() */
 
 
 /*-------------------------------------------------------------------------
@@ -5052,10 +5055,10 @@ test_scaleoffset_double(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_double() */
 
 
 /*-------------------------------------------------------------------------
@@ -5182,10 +5185,10 @@ test_scaleoffset_double_2(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 error:
-    return -1;
-}
+    return FAIL;
+} /* end test_scaleoffset_double_2() */
 
 
 /*-------------------------------------------------------------------------
@@ -5242,17 +5245,17 @@ test_multiopen (hid_t file)
     if(H5Pclose(dcpl) < 0) goto error;
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
  error:
     H5E_BEGIN_TRY {
-    H5Dclose(dset1);
-    H5Dclose(dset2);
-    H5Sclose(space);
-    H5Pclose(dcpl);
+        H5Dclose(dset1);
+        H5Dclose(dset2);
+        H5Sclose(space);
+        H5Pclose(dcpl);
     } H5E_END_TRY;
-    return -1;
-}
+    return FAIL;
+} /* end test_multiopen() */
 
 
 /*-------------------------------------------------------------------------
@@ -5338,7 +5341,7 @@ test_types(hid_t file)
     /* Cleanup */
     if(H5Gclose(grp) < 0) goto error;
     PASSED();
-    return 0;
+    return SUCCEED;
 
  error:
     H5E_BEGIN_TRY {
@@ -5347,8 +5350,8 @@ test_types(hid_t file)
     H5Sclose(space);
     H5Dclose(dset);
     } H5E_END_TRY;
-    return -1;
-}
+    return FAIL;
+} /* end test_types() */
 
 /* This message derives from H5Z */
 const H5Z_class2_t H5Z_CAN_APPLY_TEST[1] = {{
@@ -5525,10 +5528,10 @@ test_can_apply(hid_t file)
 
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
+    return FAIL;
 } /* end test_can_apply() */
 
 /* This message derives from H5Z */
@@ -5684,10 +5687,10 @@ test_can_apply2(hid_t file)
 
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
+    return FAIL;
 } /* end test_can_apply2() */
 
 
@@ -5876,11 +5879,11 @@ file)
     SKIPPED();
     puts("    Szip filter is not enabled.");
 #endif /* H5_HAVE_FILTER_SZIP */
-    return 0;
+    return SUCCEED;
 
 #ifdef H5_HAVE_FILTER_SZIP
 error:
-    return -1;
+    return FAIL;
 #endif /* H5_HAVE_FILTER_SZIP */
 } /* end test_can_apply_szip() */
 
@@ -6155,10 +6158,10 @@ test_set_local(hid_t fapl)
 
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
-    return -1;
+    return FAIL;
 } /* end test_set_local() */
 
 
@@ -6233,7 +6236,7 @@ test_compare_dcpl(hid_t file)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6243,7 +6246,7 @@ error:
         H5Pclose(dcpl1);
         H5Pclose(dcpl2);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_compare_dcpl() */
 
 
@@ -6360,7 +6363,7 @@ test_copy_dcpl(hid_t file, hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6375,7 +6378,7 @@ error:
         H5Pclose(dcpl1_copy);
         H5Pclose(dcpl2_copy);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_copy_dcpl() */
 
 
@@ -6492,7 +6495,7 @@ test_filter_delete(hid_t file)
 #else
     SKIPPED();
 #endif
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6501,7 +6504,7 @@ error:
         H5Dclose(dsid);
         H5Sclose(sid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_filter_delete() */
 
 
@@ -6574,7 +6577,7 @@ auxread_fdata(hid_t fid, const char *name)
     if(buf)
         HDfree(buf);
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6586,8 +6589,8 @@ error:
         if(buf)
             HDfree(buf);
     } H5E_END_TRY;
-    return -1;
-}
+    return FAIL;
+} /* end auxread_fdata() */
 
 
 /*-------------------------------------------------------------------------
@@ -6647,7 +6650,7 @@ test_filters_endianess(void)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6656,7 +6659,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_filters_endianess() */
 
 
@@ -6806,7 +6809,7 @@ test_zero_dims(hid_t file)
     if(H5Sclose(s2) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -6820,7 +6823,7 @@ error:
         H5Dclose(d2);
         H5Sclose(s2);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_zero_dims() */
 
 
@@ -6999,7 +7002,7 @@ test_missing_chunk(hid_t file)
     if(H5Dclose(did2) < 0) TEST_ERROR;
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -7012,7 +7015,7 @@ error:
         H5Sclose(s);
         H5Sclose(sid2);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_missing_chunk() */
 
 
@@ -7370,7 +7373,7 @@ test_random_chunks_real(const char *testname, hbool_t early_alloc, hid_t fapl)
     if(H5Fclose(file) < 0) TEST_ERROR;
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -7380,7 +7383,7 @@ error:
         H5Dclose(d);
         H5Fclose(file);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_random_chunks_real() */
 
 
@@ -7627,10 +7630,10 @@ test_deprec(hid_t file)
 
     if(H5Pclose(dcpl) < 0) goto error;
 
-    return 0;
+    return SUCCEED;
 
  error:
-    return -1;
+    return FAIL;
 } /* end test_deprec() */
 #endif /* H5_NO_DEPRECATED_SYMBOLS */
 
@@ -7734,7 +7737,7 @@ test_huge_chunks(hid_t fapl)
     if(H5Fclose(fid) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -7743,7 +7746,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_huge_chunks() */
 
 
@@ -7938,7 +7941,7 @@ test_chunk_cache(hid_t fapl)
     if (H5Fclose(fid) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -7951,7 +7954,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_chunk_cache() */
 
 
@@ -8225,7 +8228,7 @@ test_big_chunks_bypass_cache(hid_t fapl)
     HDfree(rdata2);
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -8244,7 +8247,7 @@ error:
         HDfree(rdata1);
     if(rdata2)
         HDfree(rdata2);
-    return -1;
+    return FAIL;
 } /* end test_big_chunks_bypass_cache() */
 
 
@@ -8580,7 +8583,7 @@ test_chunk_fast(const char *env_h5_driver, hid_t fapl)
     if(H5Pclose(my_fapl) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -8591,7 +8594,7 @@ error:
         H5Fclose(fid);
         H5Pclose(my_fapl);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_chunk_fast() */
 
 
@@ -8704,7 +8707,7 @@ test_reopen_chunk_fast(hid_t fapl)
     } /* end for */
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -8714,7 +8717,7 @@ error:
         H5Sclose(scalar_sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_reopen_chunk_fast() */
 
 
@@ -8813,7 +8816,7 @@ test_chunk_fast_bug1(hid_t fapl)
     if(H5Sclose(sid) < 0) FAIL_STACK_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -8822,7 +8825,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_chunk_fast_bug1() */
 
 /* This message derives from H5Z */
@@ -9268,7 +9271,7 @@ test_chunk_expand(hid_t fapl)
         PASSED();
     } /* end else */
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -9281,7 +9284,7 @@ error:
         H5Sclose(scalar_sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_chunk_expand() */
 
 
@@ -9686,7 +9689,7 @@ test_fixed_array(hid_t fapl)
     HDfree(rbuf_big);
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -9700,7 +9703,7 @@ error:
         HDfree(wbuf_big);
     if(rbuf_big)
         HDfree(rbuf_big);
-    return -1;
+    return FAIL;
 } /* end test_fixed_array() */
 
 
@@ -9944,7 +9947,7 @@ test_single_chunk(hid_t fapl)
     HDfree(t_rbuf);
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -9964,7 +9967,7 @@ error:
         HDfree(t_wbuf);
     if(t_rbuf)
         HDfree(t_rbuf);
-    return -1;
+    return FAIL;
 } /* end test_single_chunk() */
 
 
@@ -10030,15 +10033,15 @@ test_idx_compatible(void)
     }
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
         H5Dclose(did);
     H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
-} /* test_idx_compatible */
+    return FAIL;
+} /* end test_idx_compatible() */
 
 /*-------------------------------------------------------------------------
  *
@@ -10168,7 +10171,7 @@ test_unfiltered_edge_chunks(hid_t fapl)
         TEST_ERROR
 
     PASSED();
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10177,8 +10180,8 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
-} /* test_unfiltered_edge_chunks */
+    return FAIL;
+} /* end test_unfiltered_edge_chunks() */
 
 
 /*-------------------------------------------------------------------------
@@ -10282,7 +10285,7 @@ test_large_chunk_shrink(hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10292,7 +10295,7 @@ error:
         H5Sclose(scalar_sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_large_chunk_shrink() */
 
 
@@ -10376,7 +10379,7 @@ test_zero_dim_dset(hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10385,7 +10388,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_zero_dim_dset() */
 
 
@@ -10426,7 +10429,7 @@ test_swmr_non_latest(const char *env_h5_driver, hid_t fapl)
     if(!H5FD__supports_swmr_test(env_h5_driver)) {
         SKIPPED();
         HDputs("    Test skipped due to VFD not supporting SWMR I/O.");
-        return 0;
+        return SUCCEED;
     }
 
     /* Check if we are using the latest version of the format */
@@ -10625,7 +10628,7 @@ test_swmr_non_latest(const char *env_h5_driver, hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10635,7 +10638,7 @@ error:
         H5Gclose(gid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* test_swmr_non_latest() */
 
 
@@ -10676,7 +10679,7 @@ test_earray_hdr_fd(const char *env_h5_driver, hid_t fapl)
     if(!H5FD__supports_swmr_test(env_h5_driver)) {
         SKIPPED();
         HDputs("    Test skipped due to VFD not supporting SWMR I/O.");
-        return 0;
+        return SUCCEED;
     }
 
     if((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0)
@@ -10743,7 +10746,7 @@ test_earray_hdr_fd(const char *env_h5_driver, hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10755,7 +10758,7 @@ error:
         H5Sclose(sid);
         H5Sclose(msid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* test_earray_hdr_fd() */
 
 
@@ -10796,7 +10799,7 @@ test_farray_hdr_fd(const char *env_h5_driver, hid_t fapl)
     if(!H5FD__supports_swmr_test(env_h5_driver)) {
         SKIPPED();
         HDputs("    Test skipped due to VFD not supporting SWMR I/O.");
-        return 0;
+        return SUCCEED;
     }
 
     if((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0)
@@ -10863,7 +10866,7 @@ test_farray_hdr_fd(const char *env_h5_driver, hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10875,8 +10878,8 @@ error:
         H5Sclose(sid);
         H5Sclose(msid);
     } H5E_END_TRY;
-    return -1;
-} /* test_farray_hdr_fd() */
+    return FAIL;
+} /* end test_farray_hdr_fd() */
 
 
 /*-------------------------------------------------------------------------
@@ -10916,7 +10919,7 @@ test_bt2_hdr_fd(const char *env_h5_driver, hid_t fapl)
     if(!H5FD__supports_swmr_test(env_h5_driver)) {
         SKIPPED();
         HDputs("    Test skipped due to VFD not supporting SWMR I/O.");
-        return 0;
+        return SUCCEED;
     }
 
     if((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0)
@@ -10983,7 +10986,7 @@ test_bt2_hdr_fd(const char *env_h5_driver, hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -10995,8 +10998,8 @@ error:
         H5Sclose(sid);
         H5Sclose(msid);
     } H5E_END_TRY;
-    return -1;
-} /* test_bt2_hdr_fd() */
+    return FAIL;
+} /* end test_bt2_hdr_fd() */
 
 
 /*-------------------------------------------------------------------------
@@ -11379,7 +11382,7 @@ test_storage_size(hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -11389,7 +11392,7 @@ error:
         H5Sclose(sid);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_storage_size() */
 
 
@@ -11470,7 +11473,7 @@ test_power2up(hid_t fapl)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -11480,7 +11483,7 @@ error:
         H5Pclose(dcpl);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_power2up() */
 
 
@@ -11792,13 +11795,13 @@ test_scatter(void)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
         H5Sclose(sid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_scatter() */
 
 
@@ -11860,7 +11863,7 @@ gather_cb(const void *dst_buf, size_t dst_buf_bytes_used,
 
 error:
     return FAIL;
-}
+} /* end gather_cb() */
 
 static herr_t
 test_gather(void)
@@ -12154,13 +12157,13 @@ test_gather(void)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
         H5Sclose(sid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_gather() */
 
 
@@ -12194,7 +12197,7 @@ scatter_error_cb_fail(void **src_buf/*out*/, size_t *src_buf_bytes_used/*out*/,
     *src_buf_bytes_used = nelmts * sizeof(scatter_info->src_buf[0]);
 
     return FAIL;
-}
+} /* end scatter_error_cb_fail() */
 
 static herr_t
 scatter_error_cb_null(void **src_buf/*out*/, size_t *src_buf_bytes_used/*out*/,
@@ -12212,7 +12215,7 @@ scatter_error_cb_null(void **src_buf/*out*/, size_t *src_buf_bytes_used/*out*/,
     *src_buf_bytes_used = nelmts * sizeof(scatter_info->src_buf[0]);
 
     return SUCCEED;
-}
+} /* end scatter_error_cb_null() */
 
 static herr_t
 scatter_error_cb_unalign(void **src_buf/*out*/, size_t *src_buf_bytes_used/*out*/,
@@ -12223,7 +12226,7 @@ scatter_error_cb_unalign(void **src_buf/*out*/, size_t *src_buf_bytes_used/*out*
     *src_buf_bytes_used = *(size_t *)_src_buf_bytes_used;
 
     return SUCCEED;
-}
+} /* endscatter_error_cb_unalign() */
 
 static herr_t
 test_scatter_error(void)
@@ -12357,13 +12360,13 @@ test_scatter_error(void)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
         H5Sclose(sid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_scatter_error() */
 
 
@@ -12386,7 +12389,7 @@ gather_error_cb_fail(const void H5_ATTR_UNUSED *dst_buf,
     size_t H5_ATTR_UNUSED dst_buf_bytes_used, void H5_ATTR_UNUSED *op_data)
 {
     return FAIL;
-}
+} /* end gather_error_cb_fail() */
 
 static herr_t
 test_gather_error(void)
@@ -12496,13 +12499,13 @@ test_gather_error(void)
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
         H5Sclose(sid);
     } H5E_END_TRY;
-    return -1;
+    return FAIL;
 } /* end test_gather_error() */
 
 /*-------------------------------------------------------------------------
@@ -12599,8 +12602,8 @@ static herr_t dls_01_read_stuff( hid_t fid );
 static herr_t dls_01_main( void );
 
 static herr_t
-dls_01_setup_file( hid_t fid ) {
-
+dls_01_setup_file( hid_t fid )
+{
     int status = 0;
     hid_t sid = 0, did = 0, tid = 0, dcpl = 0;
     int ndims = 1;
@@ -12638,17 +12641,15 @@ dls_01_setup_file( hid_t fid ) {
     status = H5Sclose( sid );
     if ( status != 0 ) TEST_ERROR
 
-    return 0;
+    return SUCCEED;
 
 error:
-
-    return -1;
-
-} /* dls_01_setup_file */
+    return FAIL;
+} /* end dls_01_setup_file() */
 
 static herr_t
-dls_01_write_data( hid_t fid, char* buffer ) {
-
+dls_01_write_data( hid_t fid, char* buffer )
+{
     int status = 0;
     hid_t did = 0, tid = 0;
     hsize_t extent[1] = {4};
@@ -12674,17 +12675,15 @@ dls_01_write_data( hid_t fid, char* buffer ) {
     status = H5Dclose( did );
     if ( status != 0 ) TEST_ERROR
 
-    return 0;
+    return SUCCEED;
 
 error:
-
-    return -1;
-
-} /* dls_01_write_data */
+    return FAIL;
+} /* end dls_01_write_data() */
 
 static herr_t
-dls_01_read_stuff( hid_t fid ) {
-
+dls_01_read_stuff( hid_t fid )
+{
     int status = 0;
     hid_t did = 0;
     H5O_info_t info;
@@ -12698,17 +12697,15 @@ dls_01_read_stuff( hid_t fid ) {
     status = H5Dclose( did );
     if ( status != 0 ) TEST_ERROR
 
-    return 0;
+    return SUCCEED;
 
 error:
-
-    return -1;
-
-} /* dls_01_read_stuff() */
+    return FAIL;
+} /* end dls_01_read_stuff() */
 
 static herr_t
-dls_01_main( void ) {
-
+dls_01_main( void )
+{
     char filename[512];
     int status = 0;
     hid_t fapl = 0, fid = 0;
@@ -12765,15 +12762,12 @@ dls_01_main( void ) {
 
     PASSED();
 
-    return 0;
+    return SUCCEED;
 
 error:
-
     if ( buffer ) HDfree(buffer);
-
-    return -1;
-
-} /* dls_01_main() */
+    return FAIL;
+} /* end dls_01_main() */
 
 /*-------------------------------------------------------------------------
  * Function:    test_compact_open_close_dirty
@@ -12881,7 +12875,7 @@ test_compact_open_close_dirty(hid_t fapl)
         TEST_ERROR
 
      PASSED();
-     return 0;
+     return SUCCEED;
 
 error:
     H5E_BEGIN_TRY {
@@ -12890,8 +12884,8 @@ error:
         H5Dclose(did);
         H5Fclose(fid);
     } H5E_END_TRY;
-    return -1;
-} /* test_compact_open_close_dirty() */
+    return FAIL;
+} /* end test_compact_open_close_dirty() */
 
 
 /*-------------------------------------------------------------------------
@@ -13030,7 +13024,7 @@ test_versionbounds(void)
         TEST_ERROR
     dcpl = -1;
     PASSED();
-    return 0;
+    return SUCCEED;
 
  error:
     H5E_BEGIN_TRY {
@@ -13043,8 +13037,126 @@ test_versionbounds(void)
         H5Fclose(srcfile);
         H5Fclose(vfile);
     } H5E_END_TRY;
-    return -1;
-} /* test_versionbounds() */
+    return FAIL;
+} /* end test_versionbounds() */
+
+
+/*-----------------------------------------------------------------------------
+ * Function:   test_object_header_minimization_dcpl
+ *
+ * Purpose:    Test the "datset object header minimization" property as part of
+ *             the DCPL.
+ *
+ * Return:     Success/pass:   0
+ *             Failure/error: -1
+ *
+ * Programmer: Jacob Smith
+ *             2018 August 15
+ *
+ * Changes:    None.
+ *-----------------------------------------------------------------------------
+ */
+static herr_t
+test_object_header_minimization_dcpl(void)
+{
+    hid_t    dcpl_id  = -1;
+    hid_t    file_id  = -1;
+    char     filename[FILENAME_BUF_SIZE] = "";
+    hbool_t  minimize = FALSE;
+    herr_t   ret;
+
+    TESTING("dcpl flags to minimize dataset object header");
+
+    /*********/
+    /* SETUP */
+    /*********/
+
+    if(NULL == h5_fixname(OHMIN_FILENAME_A, H5P_DEFAULT, filename, sizeof(filename)))
+        FAIL_PUTS_ERROR("unable to prepare filename")
+
+    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+    if (0 > file_id)
+        FAIL_PUTS_ERROR("unable to create test file\n");
+
+    dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
+    if (0 > dcpl_id)
+        FAIL_PUTS_ERROR("unable to create DCPL\n");
+
+    /*********/
+    /* TESTS */
+    /*********/
+
+    /* default value (not set explicitly)
+     */
+    if (H5Pget_dset_no_attrs_hint(dcpl_id, &minimize) == FAIL)
+        FAIL_PUTS_ERROR("unable to get minimize value\n");
+    if (FALSE != minimize)
+        FAIL_PUTS_ERROR("Expected FALSE default but was not!\n");
+
+    /* FALSE-set value
+     */
+    if (H5Pset_dset_no_attrs_hint(dcpl_id, FALSE) == FAIL)
+        FAIL_PUTS_ERROR("unable to set minimize value to FALSE\n");
+    if (H5Pget_dset_no_attrs_hint(dcpl_id, &minimize) == FAIL)
+        FAIL_PUTS_ERROR("unable to get minimize value\n");
+    if (FALSE != minimize)
+        FAIL_PUTS_ERROR("Expected FALSE default but was not!\n");
+
+    /* TRUE-set value
+     */
+    if (H5Pset_dset_no_attrs_hint(dcpl_id, TRUE) == FAIL)
+        FAIL_PUTS_ERROR("unable to set minimize value to TRUE\n");
+    if (H5Pget_dset_no_attrs_hint(dcpl_id, &minimize) == FAIL)
+        FAIL_PUTS_ERROR("unable to get minimize value\n");
+    if (TRUE != minimize)
+        FAIL_PUTS_ERROR("Expected TRUE default but was not!\n");
+
+    /* error cases
+     */
+    H5E_BEGIN_TRY {
+        ret = H5Pget_dset_no_attrs_hint(-1, &minimize);
+    } H5E_END_TRY;
+    if (ret == SUCCEED)
+        FAIL_PUTS_ERROR("Invalid DCPL ID should fail\n");
+
+    H5E_BEGIN_TRY {
+        ret = H5Pset_dset_no_attrs_hint(-1, FALSE);
+    } H5E_END_TRY;
+    if (ret == SUCCEED)
+        FAIL_PUTS_ERROR("Invalid DCPL ID should fail\n");
+
+    H5E_BEGIN_TRY {
+        ret = H5Pset_dset_no_attrs_hint(-1, TRUE);
+    } H5E_END_TRY;
+    if (ret == SUCCEED)
+        FAIL_PUTS_ERROR("Invalid DCPL ID should fail\n");
+
+    H5E_BEGIN_TRY {
+        ret = H5Pget_dset_no_attrs_hint(dcpl_id, NULL);
+    } H5E_END_TRY;
+    if (ret == SUCCEED)
+        FAIL_PUTS_ERROR("NULL out pointer should fail\n");
+
+    /************/
+    /* TEARDOWN */
+    /************/
+
+    if (H5Fclose(file_id) == FAIL)
+        FAIL_PUTS_ERROR("can't close FILE");
+
+    if (H5Pclose(dcpl_id) == FAIL)
+        FAIL_PUTS_ERROR("unable to close DCPL\n");
+
+    PASSED();
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        H5Pclose(dcpl_id);
+        H5Fclose(file_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* end test_object_header_minimization_dcpl() */
 
 
 /*-------------------------------------------------------------------------
@@ -13068,6 +13180,7 @@ main(void)
     hid_t    fcpl = -1, fcpl2 = -1;
     unsigned new_format;
     unsigned paged;
+    unsigned minimized_ohdr;
     int      mdc_nelmts;
     size_t   rdcc_nelmts;
     size_t   rdcc_nbytes;
@@ -13118,10 +13231,12 @@ main(void)
     /* Test with paged aggregation enabled or not */
     for(paged = FALSE; paged <= TRUE; paged++) {
 
-        /* Temporary: skip testing for multi/split drivers:
-             fail file create when persisting free-space or using paged aggregation strategy */
-        if(!contig_addr_vfd && paged)
-            continue;
+      /* Temporary: skip testing for multi/split drivers:
+           fail file create when persisting free-space or using paged aggregation strategy */
+      if(!contig_addr_vfd && paged)
+          continue;
+
+      for (minimized_ohdr = FALSE; minimized_ohdr <= TRUE; minimized_ohdr++) {
 
         /* Test with old & new format groups */
         for(new_format = FALSE; new_format <= TRUE; new_format++) {
@@ -13153,6 +13268,12 @@ main(void)
             if((file = H5Fcreate(filename, H5F_ACC_TRUNC, my_fcpl, my_fapl)) < 0)
                 goto error;
 
+            if (TRUE == minimized_ohdr) {
+                if (0 > H5Fset_dset_no_attrs_hint(file, TRUE))
+                    goto error;
+                puts("(minimized dataset object headers with file setting)");
+            }
+
             /* Cause the library to emit initial messages */
             if((grp = H5Gcreate2(file, "emit diagnostics", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
                 goto error;
@@ -13230,6 +13351,7 @@ main(void)
             if(H5Fclose(file) < 0)
                 goto error;
         } /* end for new_format */
+      } /* for minimized dset object headers */
     } /* end for paged */
 
     /* Close property lists */
@@ -13246,6 +13368,8 @@ main(void)
     /* Tests version bounds using its own file */
     nerrors += (test_versionbounds() < 0             ? 1 : 0);
 
+    nerrors += (test_object_header_minimization_dcpl() < 0 ? 1 : 0);
+
     /* Run misc tests */
     nerrors += dls_01_main();
 
@@ -13261,12 +13385,12 @@ main(void)
 #endif /* H5_HAVE_FILTER_SZIP */
     h5_cleanup(FILENAME, fapl);
 
-    return 0;
+    return EXIT_SUCCESS;
 
 error:
     nerrors = MAX(1, nerrors);
     printf("***** %d DATASET TEST%s FAILED! *****\n",
             nerrors, 1 == nerrors ? "" : "S");
-    return 1;
-}
+    return EXIT_FAILURE;
+} /* end main() */
 
diff --git a/test/enc_dec_plist.c b/test/enc_dec_plist.c
index dc9a62e..33d23dc 100644
--- a/test/enc_dec_plist.c
+++ b/test/enc_dec_plist.c
@@ -146,6 +146,9 @@ main(void)
     if((H5Pset_fill_value(dcpl, H5T_NATIVE_DOUBLE, &fill)) < 0)
         FAIL_STACK_ERROR
 
+    if((H5Pset_dset_no_attrs_hint(dcpl, FALSE)) < 0)
+        FAIL_STACK_ERROR
+
     max_size[0] = 100;
     if((H5Pset_external(dcpl, "ext1.data", (off_t)0, 
                          (hsize_t)(max_size[0] * sizeof(int)/4))) < 0)
diff --git a/test/gen_plist.c b/test/gen_plist.c
index af248be..68da6cc 100644
--- a/test/gen_plist.c
+++ b/test/gen_plist.c
@@ -125,6 +125,9 @@ main(void)
     if((ret = H5Pset_fill_value(dcpl1, H5T_STD_I32BE, &fill)) < 0)
         assert(ret > 0);
 
+    if((ret = H5Pset_dset_no_attrs_hint(dcpl1, FALSE)) < 0)
+        assert(ret > 0);
+
     max_size[0] = 100;
     if((ret = H5Pset_external(dcpl1, "ext1.data", (off_t)0, 
                          (hsize_t)(max_size[0] * sizeof(int)/4))) < 0)
diff --git a/test/h5test.c b/test/h5test.c
index 0226aa7..32638e6 100644
--- a/test/h5test.c
+++ b/test/h5test.c
@@ -158,47 +158,8 @@ h5_clean_files(const char *base_name[], hid_t fapl)
     int i;
 
     for(i = 0; base_name[i]; i++) {
-        char filename[1024];
-        char temp[2048];
-        hid_t driver;
-
-        if(NULL == h5_fixname(base_name[i], fapl, filename, sizeof(filename)))
-            continue;
-
-        driver = H5Pget_driver(fapl);
-
-        if(driver == H5FD_FAMILY) {
-            int j;
-
-            for(j = 0; /*void*/; j++) {
-                HDsnprintf(temp, sizeof temp, filename, j);
-
-                if(HDaccess(temp, F_OK) < 0)
-                    break;
-
-                HDremove(temp);
-            } /* end for */
-        } else if(driver == H5FD_CORE) {
-            hbool_t backing;        /* Whether the core file has backing store */
-
-            H5Pget_fapl_core(fapl, NULL, &backing);
-
-            /* If the file was stored to disk with bacing store, remove it */
-            if(backing)
-                HDremove(filename);
-        } else if (driver == H5FD_MULTI) {
-            H5FD_mem_t mt;
-
-            HDassert(HDstrlen(multi_letters)==H5FD_MEM_NTYPES);
-
-            for(mt = H5FD_MEM_DEFAULT; mt < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t,mt)) {
-                HDsnprintf(temp, sizeof temp, "%s-%c.h5", filename, multi_letters[mt]);
-                HDremove(temp); /*don't care if it fails*/
-            } /* end for */
-        } else {
-            HDremove(filename);
-        }
-    } /* end for */
+        h5_delete_test_file(base_name[i], fapl);
+    }
 
     /* Close the FAPL used to access the file */
     H5Pclose(fapl);
@@ -266,10 +227,10 @@ h5_delete_test_file(const char *base_name, hid_t fapl)
         for(mt = H5FD_MEM_DEFAULT; mt < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t,mt)) {
             HDsnprintf(sub_filename, sizeof(sub_filename), "%s-%c.h5", filename, multi_letters[mt]);
             HDremove(sub_filename);
-        } /* end for */
+        }
     } else {
         HDremove(filename);
-    } /* end if */
+    } /* end driver selection tree */
 
     return;
 } /* end h5_delete_test_file() */
@@ -652,7 +613,7 @@ h5_fixname_real(const char *base_name, hid_t fapl, const char *_suffix,
                 printf("*** Hint ***\n"
                        "You can use environment variable HDF5_PARAPREFIX to "
                        "run parallel test files in a\n"
-                       "different directory or to add file type prefix. E.g.,\n"
+                       "different directory or to add file type prefix. e.g.,\n"
                        "   HDF5_PARAPREFIX=pfs:/PFS/user/me\n"
                        "   export HDF5_PARAPREFIX\n"
                        "*** End of Hint ***\n");
diff --git a/test/links.c b/test/links.c
index b10d0ad..b09ddb1 100644
--- a/test/links.c
+++ b/test/links.c
@@ -315,6 +315,8 @@ typedef struct {
     const obj_visit_t *info;    /* Pointer to the object visit structure to use */
 } ovisit_ud_t;
 
+static hid_t dcpl_g; /* for [un]minimized dataset object headers */
+
 
 
 /*-------------------------------------------------------------------------
@@ -377,7 +379,7 @@ mklinks(hid_t fapl, hbool_t new_format)
     if(H5Gclose(grp) < 0) TEST_ERROR
 
     /* Create a dataset */
-    if((d1 = H5Dcreate2(file, "d1", H5T_NATIVE_INT, scalar, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((d1 = H5Dcreate2(file, "d1", H5T_NATIVE_INT, scalar, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(d1) < 0) TEST_ERROR
 
     /* Create a hard link */
@@ -451,8 +453,8 @@ new_links(hid_t fapl, hbool_t new_format)
     if((grp2_b = H5Gcreate2(file_b, "grp2", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
 
     /* Create datasets */
-    if((dset1 = H5Dcreate2(file_a, "dataset1", H5T_NATIVE_INT, scalar, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
-    if((dset2 = H5Dcreate2(grp1_a, "dataset2", H5T_NATIVE_INT, scalar, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((dset1 = H5Dcreate2(file_a, "dataset1", H5T_NATIVE_INT, scalar, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((dset2 = H5Dcreate2(grp1_a, "dataset2", H5T_NATIVE_INT, scalar, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
 
     /* Create links within a file.  Both of source and destination use
      * H5L_SAME_LOC.  Both hard and soft links should fail. */
@@ -545,7 +547,7 @@ cklinks(hid_t fapl, hbool_t new_format)
     if(H5Oget_info_by_name2(file, "grp1/hard", &oinfo2, H5O_INFO_BASIC, H5P_DEFAULT) < 0) FAIL_STACK_ERROR
     if(H5O_TYPE_DATASET != oinfo2.type) {
 	H5_FAILED();
-	printf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
+	HDprintf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(H5F_addr_ne(oinfo1.addr, oinfo2.addr)) {
@@ -580,7 +582,7 @@ cklinks(hid_t fapl, hbool_t new_format)
     if(H5Oget_info_by_name2(file, "grp1/soft", &oinfo2, H5O_INFO_BASIC, H5P_DEFAULT) < 0) FAIL_STACK_ERROR
     if(H5O_TYPE_DATASET != oinfo2.type) {
 	H5_FAILED();
-	printf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
+	HDprintf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(H5F_addr_ne(oinfo1.addr, oinfo2.addr)) {
@@ -609,12 +611,12 @@ cklinks(hid_t fapl, hbool_t new_format)
     if(H5Lget_info(file, "grp1/dangle", &linfo2, H5P_DEFAULT) < 0) FAIL_STACK_ERROR
     if(H5L_TYPE_SOFT != linfo2.type) {
 	H5_FAILED();
-	printf("    %d: Unexpected object type should have been a symbolic link\n", __LINE__);
+	HDprintf("    %d: Unexpected object type should have been a symbolic link\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(H5Lget_val(file, "grp1/dangle", linkval, sizeof linkval, H5P_DEFAULT) < 0) {
 	H5_FAILED();
-	printf("    %d: Can't retrieve link value\n", __LINE__);
+	HDprintf("    %d: Can't retrieve link value\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(HDstrcmp(linkval, "foobar")) {
@@ -636,12 +638,12 @@ cklinks(hid_t fapl, hbool_t new_format)
     if(H5Lget_info(file, "grp1/recursive", &linfo2, H5P_DEFAULT) < 0) FAIL_STACK_ERROR
     if(H5L_TYPE_SOFT != linfo2.type) {
 	H5_FAILED();
-	printf("    %d: Unexpected object type should have been a symbolic link\n", __LINE__);
+	HDprintf("    %d: Unexpected object type should have been a symbolic link\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(H5Lget_val(file, "grp1/recursive", linkval, sizeof linkval, H5P_DEFAULT) < 0) {
 	H5_FAILED();
-	printf("    %d: Can't retrieve link value\n", __LINE__);
+	HDprintf("    %d: Can't retrieve link value\n", __LINE__);
 	TEST_ERROR
     } /* end if */
     if(HDstrcmp(linkval, "/grp1/recursive")) {
@@ -706,7 +708,7 @@ ck_new_links(hid_t fapl, hbool_t new_format)
     /* Check hard links */
     if(H5O_TYPE_DATASET != oi_hard1.type || H5O_TYPE_DATASET != oi_hard2.type) {
 	H5_FAILED();
-	printf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
+	HDprintf("    %d: Unexpected object type should have been a dataset\n", __LINE__);
 	TEST_ERROR
     }
     if(H5F_addr_ne(oi_dset.addr, oi_hard1.addr) || H5F_addr_ne(oi_dset.addr, oi_hard2.addr)) {
@@ -1014,7 +1016,7 @@ test_lcpl(hid_t fapl, hbool_t new_format)
     if((space_id=H5Screate_simple(2 ,dims, NULL)) < 0) TEST_ERROR
 
     /* Create a dataset using the default LCPL */
-    if((dset_id = H5Dcreate2(file_id, "/dataset", H5T_NATIVE_INT, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((dset_id = H5Dcreate2(file_id, "/dataset", H5T_NATIVE_INT, space_id, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(dset_id) < 0) TEST_ERROR
 
     /* Check that its character encoding is the default */
@@ -1043,7 +1045,7 @@ test_lcpl(hid_t fapl, hbool_t new_format)
     if(linfo.cset != H5T_CSET_UTF8) TEST_ERROR
 
     /* Create a dataset using the new LCPL */
-    if((dset_id = H5Dcreate2(file_id, "/dataset2", H5T_NATIVE_INT, space_id, lcpl_id, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((dset_id = H5Dcreate2(file_id, "/dataset2", H5T_NATIVE_INT, space_id, lcpl_id, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(dset_id) < 0) TEST_ERROR
 
     /* Check that its character encoding is UTF-8 */
@@ -2602,7 +2604,7 @@ external_link_toomany(hid_t fapl, hbool_t new_format)
     } H5E_END_TRY;
     if (gid >= 0) {
 	H5_FAILED();
-	printf("%d:    Should have failed for sequence of too many nested links.", __LINE__);
+	HDprintf("%d:    Should have failed for sequence of too many nested links.", __LINE__);
 	goto error;
     }
 
@@ -3758,7 +3760,11 @@ external_set_elink_fapl2(hid_t fapl, hbool_t new_format)
     if((space = H5Screate_simple(2, dims, NULL)) < 0) TEST_ERROR
 
     /* Create dataset creation property list */
-    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0) TEST_ERROR;
+    if (dcpl_g == H5P_DEFAULT)
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+    else
+        dcpl = H5Pcopy(dcpl_g);
+    if (0 > dcpl) TEST_ERROR;
     if(H5Pset_alloc_time(dcpl, H5D_ALLOC_TIME_LATE) < 0) TEST_ERROR;
 
     /* create "Dataset" in group "A" of target file */
@@ -6100,7 +6106,7 @@ external_link_closing(hid_t fapl, hbool_t new_format)
     /* Test creating each kind of object */
     if((gid = H5Gcreate2(fid1, "elink/elink/elink/group1", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Tcommit2(fid1, "elink/elink/elink/type1", tid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT) < 0) TEST_ERROR
-    if((did = H5Dcreate2(fid1, "elink/elink/elink/dataset1", tid2, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(fid1, "elink/elink/elink/dataset1", tid2, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
 
     /* Close objects */
     if(H5Gclose(gid) < 0) TEST_ERROR
@@ -7298,7 +7304,7 @@ external_open_twice(hid_t fapl, hbool_t new_format)
     if((space = H5Screate(H5S_SCALAR)) < 0)
         TEST_ERROR
     if((oid1 = H5Dcreate2(fid2, "dset", H5T_NATIVE_INT, space, H5P_DEFAULT,
-            H5P_DEFAULT, H5P_DEFAULT)) < 0)
+            dcpl_g, H5P_DEFAULT)) < 0)
         TEST_ERROR
     if(H5Dclose(oid1) < 0)
         TEST_ERROR
@@ -7514,8 +7520,11 @@ external_link_with_committed_datatype(hid_t fapl, hbool_t new_format)
     if((sid2 = H5Screate_simple(2, dims, NULL)) < 0)
         FAIL_STACK_ERROR
 
-    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
-        FAIL_STACK_ERROR
+    if (dcpl_g == H5P_DEFAULT)
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+    else
+        dcpl = H5Pcopy(dcpl_g);
+    if (0 > dcpl) FAIL_STACK_ERROR
     if(H5Pset_chunk(dcpl, 2, chunks) < 0)
         FAIL_STACK_ERROR
 
@@ -9058,7 +9067,7 @@ lapl_nlinks(hid_t fapl, hbool_t new_format)
     dims[0] = 2;
     dims[1] = 2;
     if((sid = H5Screate_simple(2, dims, NULL)) < 0) TEST_ERROR
-    if((did = H5Dcreate2(gid, "dataset", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(gid, "dataset", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(did) < 0) TEST_ERROR
 
     /* Close group */
@@ -9170,7 +9179,7 @@ linkinfo(hid_t fapl, hbool_t new_format)
     if(H5Lcreate_soft("group", fid, "softlink", H5P_DEFAULT, H5P_DEFAULT) < 0) FAIL_STACK_ERROR
 
     if((sid = H5Screate(H5S_SCALAR)) < 0) TEST_ERROR
-    if((did = H5Dcreate2(fid, "dataset", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(fid, "dataset", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
 
     if(H5Lcreate_ud(fid, "ud_link", (H5L_type_t)UD_PLIST_TYPE, NULL, (size_t)0, H5P_DEFAULT, H5P_DEFAULT) < 0) TEST_ERROR
     if(H5Lcreate_external("file_name", "obj_path", fid, "ext_link", H5P_DEFAULT, H5P_DEFAULT) < 0) TEST_ERROR
@@ -9335,13 +9344,13 @@ build_visit_file(hid_t fapl)
     /* Create dataset in each group */
     if((sid = H5Screate(H5S_SCALAR)) < 0) TEST_ERROR
 
-    if((did = H5Dcreate2(fid, "/Dataset_zero", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(fid, "/Dataset_zero", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(did) < 0) TEST_ERROR
 
-    if((did = H5Dcreate2(fid, "/Group1/Dataset_one", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(fid, "/Group1/Dataset_one", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(did) < 0) TEST_ERROR
 
-    if((did = H5Dcreate2(fid, "/Group1/Group2/Dataset_two", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+    if((did = H5Dcreate2(fid, "/Group1/Group2/Dataset_two", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT)) < 0) TEST_ERROR
     if(H5Dclose(did) < 0) TEST_ERROR
 
     if(H5Sclose(sid) < 0) TEST_ERROR
@@ -14890,6 +14899,7 @@ main(void)
     hid_t	fapl, fapl2;    /* File access property lists */
     int	nerrors = 0;
     unsigned new_format;    /* Whether to use the new format or not */
+    unsigned minimize_dset_oh;
     unsigned efc;           /* Whether to use the external file cache */
     const char  *env_h5_drvr;      /* File Driver value from environment */
 
@@ -14900,165 +14910,187 @@ main(void)
     h5_reset();
     fapl = h5_fileaccess();
 
-    /* Copy the file access property list */
+    /* fapl2 uses "latest version bounds" */
     if((fapl2 = H5Pcopy(fapl)) < 0) TEST_ERROR
-
-    /* Set the "use the latest version of the format" bounds for creating objects in the file */
     if(H5Pset_libver_bounds(fapl2, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0) TEST_ERROR
 
-    /* Loop over using new group format */
-    for(new_format = FALSE; new_format <= TRUE; new_format++) {
-        hid_t my_fapl;
+    for (minimize_dset_oh = 0; minimize_dset_oh <= 1; minimize_dset_oh++) {
+        if (minimize_dset_oh) {
+            HDprintf("\n-Testing with minimzed dataset object headers-\n");
+            dcpl_g = H5Pcreate(H5P_DATASET_CREATE);
+            if (0 > dcpl_g) TEST_ERROR
+        } else {
+            HDprintf("\n-Testing with unminimzed dataset object headers-\n");
+            dcpl_g = H5P_DEFAULT;
+        }
 
-        /* Check for FAPL to use */
-        if(new_format)
-            my_fapl = fapl2;
-        else
-            my_fapl = fapl;
-
-        /* General tests... (on both old & new format groups */
-        nerrors += mklinks(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += cklinks(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += new_links(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += ck_new_links(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += long_links(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += toomany(my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* Test new H5L link creation routine */
-        nerrors += test_lcpl(my_fapl, new_format);
-        nerrors += test_move(my_fapl, new_format);
-        nerrors += test_copy(my_fapl, new_format);
-        nerrors += test_move_preserves(my_fapl, new_format);
+        for(new_format = FALSE; new_format <= TRUE; new_format++) {
+            hid_t my_fapl;
+
+            /* Check for FAPL to use */
+            if(new_format) {
+                my_fapl = fapl2;
+                HDprintf("\n--Testing with 'new format'--\n");
+            } else {
+                my_fapl = fapl;
+                HDprintf("\n--Testing with 'old format'--\n");
+            }
+
+            /* always enter tests without external cache */
+            if(H5Pset_elink_file_cache_size(my_fapl, 0) < 0)
+                TEST_ERROR
+
+            /* General tests... (on both old & new format groups */
+            nerrors += mklinks(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += cklinks(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += new_links(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += ck_new_links(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += long_links(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += toomany(my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* Test new H5L link creation routine */
+            nerrors += test_lcpl(my_fapl, new_format);
+            nerrors += test_move(my_fapl, new_format);
+            nerrors += test_copy(my_fapl, new_format);
+            nerrors += test_move_preserves(my_fapl, new_format);
 #ifndef H5_NO_DEPRECATED_SYMBOLS
-        nerrors += test_deprec(my_fapl, new_format);
+            nerrors += test_deprec(my_fapl, new_format);
 #endif /* H5_NO_DEPRECATED_SYMBOLS */
 
-        /* tests for external link */
-        /* Test external file cache first, so it sees the default efc setting on
-         * the fapl */
-        nerrors += external_file_cache(my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* This test cannot run with the EFC because it assumes that an
-         * intermediate file is not held open */
-        nerrors += external_link_mult(my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* This test cannot run with the EFC because the EFC cannot currently
-         * reopen a cached file with a different intent */
-        nerrors += external_set_elink_acc_flags(env_h5_drvr, my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* Try external link tests both with and without the external file cache
-         */
-        for(efc = FALSE; efc <= TRUE; efc++) {
-            if(efc) {
-                if(H5Pset_elink_file_cache_size(my_fapl, 8) < 0)
-                    TEST_ERROR
-                printf("\n---Testing with external file cache---\n");
-            } /* end if */
-            else {
-                if(H5Pset_elink_file_cache_size(my_fapl, 0) < 0)
-                    TEST_ERROR
-                printf("\n---Testing without external file cache---\n");
-            } /* end else */
+            /* tests for external link */
+            /* Test external file cache first, so it sees the default efc setting on
+             * the fapl */
+            nerrors += external_file_cache(my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* This test cannot run with the EFC because it assumes that an
+             * intermediate file is not held open */
+            nerrors += external_link_mult(my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* This test cannot run with the EFC because the EFC cannot currently
+             * reopen a cached file with a different intent */
+            nerrors += external_set_elink_acc_flags(env_h5_drvr, my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* Try external link tests both with and without the external file cache
+             */
+            for(efc = FALSE; efc <= TRUE; efc++) {
+                if(efc) {
+                    if(H5Pset_elink_file_cache_size(my_fapl, 8) < 0)
+                        TEST_ERROR
+                    HDprintf("\n---Testing with external file cache---\n");
+                } /* end if */
+                else {
+                    if(H5Pset_elink_file_cache_size(my_fapl, 0) < 0)
+                        TEST_ERROR
+                    HDprintf("\n---Testing without external file cache---\n");
+                } /* end else */
 
-            nerrors += external_link_root(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_path(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_self(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_pingpong(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_toomany(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_dangling(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_recursive(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_query(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_unlink_compact(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_unlink_dense(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_move(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_ride(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_closing(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_endian(new_format) < 0 ? 1 : 0;
-            nerrors += external_link_strong(my_fapl, new_format) < 0 ? 1 : 0;
-
-            nerrors += external_link_prefix(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_abs_mainpath(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_rel_mainpath(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_cwd(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_abstar(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_abstar_cur(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_reltar(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_chdir(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_set_elink_fapl1(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_set_elink_fapl2(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_set_elink_fapl3(new_format) < 0 ? 1 : 0;
-            nerrors += external_set_elink_cb(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_root(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_path(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_self(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_pingpong(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_toomany(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_dangling(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_recursive(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_query(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_unlink_compact(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_unlink_dense(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_move(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_ride(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_closing(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_endian(new_format) < 0 ? 1 : 0;
+                nerrors += external_link_strong(my_fapl, new_format) < 0 ? 1 : 0;
+
+                nerrors += external_link_prefix(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_abs_mainpath(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_rel_mainpath(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_cwd(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_abstar(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_abstar_cur(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_reltar(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_chdir(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_set_elink_fapl1(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_set_elink_fapl2(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_set_elink_fapl3(new_format) < 0 ? 1 : 0;
+                nerrors += external_set_elink_cb(my_fapl, new_format) < 0 ? 1 : 0;
 #ifdef H5_HAVE_WINDOW_PATH
-            nerrors += external_link_win1(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win2(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win3(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win4(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win5(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win6(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win7(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win8(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_win9(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win1(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win2(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win3(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win4(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win5(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win6(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win7(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win8(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_link_win9(my_fapl, new_format) < 0 ? 1 : 0;
 #endif
-            nerrors += external_symlink(env_h5_drvr, my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_copy_invalid_object(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_dont_fail_to_source(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_open_twice(my_fapl, new_format) < 0 ? 1 : 0;
-            nerrors += external_link_with_committed_datatype(my_fapl, new_format) < 0 ? 1 : 0;
-        } /* end for */
-
-        /* These tests assume that external links are a form of UD links,
-         * so assume that everything that passed for external links
-         * above has already been tested for UD links.
-         */
-        if(new_format == TRUE) {
-            nerrors += ud_hard_links(fapl2) < 0 ? 1 : 0;     /* requires new format groups */
-            nerrors += ud_link_reregister(fapl2) < 0 ? 1 : 0;        /* requires new format groups */
-        } /* end if */
-        nerrors += ud_callbacks(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += ud_link_errors(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += lapl_udata(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += lapl_nlinks(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += linkinfo(my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* Misc. extra tests, useful for both new & old format files */
-        nerrors += link_visit(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += link_visit_by_name(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += obj_visit(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += obj_visit_by_name(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += obj_visit_stop(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += link_filters(my_fapl, new_format) < 0 ? 1 : 0;
-        nerrors += obj_exists(my_fapl, new_format) < 0 ? 1 : 0;
-
-        /* Keep this test last, it's testing files that are used above */
-        /* do not do this for files used by external link tests */
-        nerrors += check_all_closed(my_fapl, new_format, EXTSTOP) < 0 ? 1 : 0;
-    } /* end for */
+                nerrors += external_symlink(env_h5_drvr, my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_copy_invalid_object(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_dont_fail_to_source(my_fapl, new_format) < 0 ? 1 : 0;
+                nerrors += external_open_twice(my_fapl, new_format) < 0 ? 1 : 0;
+	        nerrors += external_link_with_committed_datatype(my_fapl, new_format) < 0 ? 1 : 0;
+            } /* with/without external file cache */
+
+            /* These tests assume that external links are a form of UD links,
+             * so assume that everything that passed for external links
+             * above has already been tested for UD links.
+             */
+            if(new_format == TRUE) {
+                nerrors += ud_hard_links(fapl2) < 0 ? 1 : 0;     /* requires new format groups */
+                nerrors += ud_link_reregister(fapl2) < 0 ? 1 : 0;        /* requires new format groups */
+            } /* end if */
+            nerrors += ud_callbacks(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += ud_link_errors(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += lapl_udata(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += lapl_nlinks(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += linkinfo(my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* Misc. extra tests, useful for both new & old format files */
+            nerrors += link_visit(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += link_visit_by_name(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += obj_visit(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += obj_visit_by_name(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += obj_visit_stop(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += link_filters(my_fapl, new_format) < 0 ? 1 : 0;
+            nerrors += obj_exists(my_fapl, new_format) < 0 ? 1 : 0;
+
+            /* Keep this test last, it's testing files that are used above */
+            /* do not do this for files used by external link tests */
+            nerrors += check_all_closed(my_fapl, new_format, EXTSTOP) < 0 ? 1 : 0;
+        } /* new/old format */
+
+        /* New group revision feature tests */
+        nerrors += corder_create_empty(fapl2) < 0 ? 1 : 0;
 
-    /* New group revision feature tests */
-    nerrors += corder_create_empty(fapl2) < 0 ? 1 : 0;
 /* XXX: when creation order indexing is fully working, go back and add checks
 *      to these tests to make certain that the creation order values are
 *      correct.
 */
-    nerrors += corder_create_compact(fapl2) < 0 ? 1 : 0;
-    nerrors += corder_create_dense(fapl2) < 0 ? 1 : 0;
-    nerrors += corder_transition(fapl2) < 0 ? 1 : 0;
-    nerrors += corder_delete(fapl2) < 0 ? 1 : 0;
-    nerrors += link_info_by_idx(fapl2) < 0 ? 1 : 0;
-    nerrors += delete_by_idx(fapl2) < 0 ? 1 : 0;
-    nerrors += link_iterate(fapl2) < 0 ? 1 : 0;
-    nerrors += open_by_idx(fapl2) < 0 ? 1 : 0;
-    nerrors += object_info(fapl2) < 0 ? 1 : 0;
-    nerrors += group_info(fapl2) < 0 ? 1 : 0;
-    nerrors += timestamps(fapl2) < 0 ? 1 : 0;
-
-    /* Test new API calls on old-style groups */
-    nerrors += link_info_by_idx_old(fapl) < 0 ? 1 : 0;
-    nerrors += delete_by_idx_old(fapl) < 0 ? 1 : 0;
-    nerrors += link_iterate_old(fapl) < 0 ? 1 : 0;
-    nerrors += open_by_idx_old(fapl) < 0 ? 1 : 0;
-    nerrors += object_info_old(fapl) < 0 ? 1 : 0;
-    nerrors += group_info_old(fapl) < 0 ? 1 : 0;
+        nerrors += corder_create_compact(fapl2) < 0 ? 1 : 0;
+        nerrors += corder_create_dense(fapl2) < 0 ? 1 : 0;
+        nerrors += corder_transition(fapl2) < 0 ? 1 : 0;
+        nerrors += corder_delete(fapl2) < 0 ? 1 : 0;
+        nerrors += link_info_by_idx(fapl2) < 0 ? 1 : 0;
+        nerrors += delete_by_idx(fapl2) < 0 ? 1 : 0;
+        nerrors += link_iterate(fapl2) < 0 ? 1 : 0;
+        nerrors += open_by_idx(fapl2) < 0 ? 1 : 0;
+        nerrors += object_info(fapl2) < 0 ? 1 : 0;
+        nerrors += group_info(fapl2) < 0 ? 1 : 0;
+        nerrors += timestamps(fapl2) < 0 ? 1 : 0;
+
+        /* Test new API calls on old-style groups */
+        nerrors += link_info_by_idx_old(fapl) < 0 ? 1 : 0;
+        nerrors += delete_by_idx_old(fapl) < 0 ? 1 : 0;
+        nerrors += link_iterate_old(fapl) < 0 ? 1 : 0;
+        nerrors += open_by_idx_old(fapl) < 0 ? 1 : 0;
+        nerrors += object_info_old(fapl) < 0 ? 1 : 0;
+        nerrors += group_info_old(fapl) < 0 ? 1 : 0;
+
+        if (minimize_dset_oh) {
+            if (H5Pclose(dcpl_g) < 0)
+                TEST_ERROR;
+            dcpl_g = -1;
+        }
+    } /* [un]minimized dataset object headers */
 
     /* Close 2nd FAPL */
     H5Pclose(fapl2);
@@ -15075,11 +15107,11 @@ main(void)
 
     /* Results */
     if(nerrors) {
-        printf("***** %d LINK TEST%s FAILED! *****\n",
+        HDprintf("***** %d LINK TEST%s FAILED! *****\n",
                 nerrors, 1 == nerrors ? "" : "S");
         HDexit(EXIT_FAILURE);
     }
-    printf("All link tests passed.\n");
+    HDprintf("All link tests passed.\n");
 
     /* clean up symlink created by external link tests */
     HDremove(SYMLINK1);
diff --git a/test/echo_vol.c b/test/null_vol_connector.c
index 7f59832..b62b370 100644
--- a/test/echo_vol.c
+++ b/test/null_vol_connector.c
@@ -10,19 +10,20 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-/*
- * Purpose:     A simple virtual object layer (VOL) plugin that just echoes
- *              the name of the API call.
+/* Purpose:     A simple virtual object layer (VOL) connector with almost no
+ *              functionality that is used for testing basic plugin handling
+ *              (registration, etc.).
  */
 
 #include "H5PLextern.h"
 
-/* The VOL class struct.
- */
-static const H5VL_class_t echo_vol_g = {
+#include "null_vol_connector.h"
+
+/* The VOL class struct */
+static const H5VL_class_t null_vol_g = {
     0,                                              /* version      */
-    (H5VL_class_value_t)501,                        /* value        */
-    "echo",                                         /* name         */
+    NULL_VOL_CONNECTOR_VALUE,                       /* value        */
+    NULL_VOL_CONNECTOR_NAME,                        /* name         */
     0,                                              /* capability flags */
     NULL,                                           /* initialize   */
     NULL,                                           /* terminate    */
@@ -106,22 +107,10 @@ static const H5VL_class_t echo_vol_g = {
     NULL                                            /* optional     */
 };
 
-
-
 /* These two functions are necessary to load this plugin using
  * the HDF5 library.
  */
 
-H5PL_type_t
-H5PLget_plugin_type(void)
-{
-    return H5PL_TYPE_VOL;
-}
-
-
-const void*
-H5PLget_plugin_info(void)
-{
-    return &echo_vol_g;
-}
+H5PL_type_t H5PLget_plugin_type(void) {return H5PL_TYPE_VOL;}
+const void *H5PLget_plugin_info(void) {return &null_vol_g;}
 
diff --git a/test/null_vol_connector.h b/test/null_vol_connector.h
new file mode 100644
index 0000000..11c8826
--- /dev/null
+++ b/test/null_vol_connector.h
@@ -0,0 +1,25 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/* Purpose:     A simple virtual object layer (VOL) connector with almost no
+ *              functionality that is used for testing basic plugin handling
+ *              (registration, etc.).
+ */
+
+#ifndef _null_vol_connector_H
+#define _null_vol_connector_H
+
+#define NULL_VOL_CONNECTOR_VALUE    ((H5VL_class_value_t)160)
+#define NULL_VOL_CONNECTOR_NAME     "null_vol_connector"
+
+#endif /* _null_vol_connector_H */
+
diff --git a/test/ohdr.c b/test/ohdr.c
index cca7e7e..042a81b 100644
--- a/test/ohdr.c
+++ b/test/ohdr.c
@@ -36,9 +36,16 @@
 
 const char *FILENAME[] = {
     "ohdr",
+    "ohdr_min_a",
+    "ohdr_min_b",
     NULL
 };
 
+/* used for object header size comparison */
+#define EQ 1
+#define LT 2
+#define GT 3
+
 /* The tbogus.h5 is generated from gen_bogus.c in HDF5 'test' directory.
  * To get this data file, define H5O_ENABLE_BOGUS in src/H5Oprivate, rebuild
  * the library and simply compile gen_bogus.c with that HDF5 library and run it.
@@ -733,6 +740,885 @@ error:
     return FAIL;
 } /* test_unknown() */
 
+/*
+ * Set an attribute with the given information.
+ * If the out parameter `attr_id` is negative, a new attribute will be
+ * created with the given information. Else, it will attempt to update the
+ * attribute with the new value.
+ *
+ * `dataspace_id` ignored if `attribute_id` >= 0
+ */
+static herr_t
+put_attribute(hid_t loc_id, const char *attrname, const void *attrvalue, hid_t datatype_id, hid_t dataspace_id, hid_t *attribute_id)
+{   
+    if((*attribute_id) < 0) {
+        hid_t id = -1;
+        id = H5Acreate(loc_id, attrname, datatype_id, dataspace_id, H5P_DEFAULT, H5P_DEFAULT);
+        if(id < 0) 
+            return FAIL;
+        *attribute_id = id;
+    }
+    return H5Awrite(*attribute_id, datatype_id, attrvalue);
+} /* put_attribute */
+
+/*
+ * Count the number of attributes attached to an object.
+ * Returns negative in event of error.
+ */
+static int
+count_attributes(hid_t dset_id)
+{   
+    H5O_info_t info;
+    
+    if(H5Oget_info(dset_id, &info, H5O_INFO_ALL) < 0)
+        return -1;
+    else
+        return (int)info.num_attrs; /* should never exceed int bounds */
+} /* count_attributes */
+
+/*
+ * Get the total space used by the object header.
+ * Used by oh_compare()
+ * On success, stores size in `size_out` pointer.
+ */
+static herr_t
+_oh_getsize(hid_t did, hsize_t *size_out)
+{
+    H5O_info_t info;
+    if(FAIL == H5Oget_info2(did, &info, H5O_INFO_HDR))
+        return FAIL;
+    *size_out = info.hdr.space.total;
+    return SUCCEED;
+} /* _oh_getsize */
+
+/*
+ * Compare the TOTAL space used by datasets' object headers.
+ * Returns negative value if an error occurred,
+ * else positive #defined indicator value EQ, LT, GT.
+ */
+static int
+oh_compare(hid_t did1, hid_t did2)
+{
+    hsize_t space1 = 0;
+    hsize_t space2 = 0;
+
+    if(FAIL == _oh_getsize(did1, &space1))
+        return -1;
+    if(FAIL == _oh_getsize(did2, &space2))
+        return -2;
+
+    if(space1 < space2)
+        return LT;
+    else if(space1 > space2)
+        return GT;
+    else
+        return EQ;
+} /* oh_compare() */
+
+/*
+ * Demonstrate attribute addition to datasets.
+ * Conduct additions side-by-side with a standard datataset and one with
+ * minimized dataset object headers.
+ */
+static herr_t
+test_minimized_dset_ohdr_attribute_addition(hid_t fapl_id)
+{
+    hsize_t array_10[1]      = {10}; /* dataspace extent */
+    char    buffer[10]       = "";   /* to inspect string attribute */
+    int     a_out            = 0;
+    char    filename[512]    = "";
+    hid_t   int_type_id      = -1;
+    hid_t   char_type_id     = -1;
+    hid_t   dcpl_id          = -1;
+    hid_t   dspace_id        = -1;
+    hid_t   dspace_scalar_id = -1;
+    hid_t   dset_id          = -1;
+    hid_t   mindset_id       = -1;
+    hid_t   attr_1_id        = -1;
+    hid_t   attr_1a_id       = -1;
+    hid_t   attr_2_id        = -1;
+    hid_t   attr_2a_id       = -1;
+    hid_t   attr_3_id        = -1;
+    hid_t   attr_3a_id       = -1;
+    hid_t   file_id          = -1;
+    herr_t  ret;
+    int     count = 0;
+
+    TESTING("minimized dset object headers attribute additions")
+
+    /*********
+     * SETUP *
+     *********/
+
+    if(h5_fixname(FILENAME[1], H5P_DEFAULT, filename, sizeof(filename)) == NULL)
+        TEST_ERROR
+
+    dspace_id = H5Screate_simple(1, array_10, NULL);
+    if(dspace_id < 0) TEST_ERROR
+
+    dspace_scalar_id = H5Screate(H5S_SCALAR);
+    if(dspace_scalar_id < 0) TEST_ERROR
+
+    char_type_id = H5Tcopy(H5T_NATIVE_CHAR);
+    if(char_type_id < 0) TEST_ERROR
+
+    int_type_id = H5Tcopy(H5T_NATIVE_INT);
+    if(int_type_id < 0) TEST_ERROR
+
+    dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_id < 0) TEST_ERROR
+
+    ret = H5Pset_dset_no_attrs_hint(dcpl_id, TRUE);
+    if(ret < 0) TEST_ERROR
+
+    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if(file_id < 0) TEST_ERROR
+
+    H5E_BEGIN_TRY {
+        count = count_attributes(dset_id);
+    } H5E_END_TRY;
+    if(count != -1) TEST_ERROR
+
+    dset_id = H5Dcreate(file_id, "dataset", int_type_id, dspace_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    if(dset_id < 0) TEST_ERROR
+
+    mindset_id  = H5Dcreate(file_id, "mindataset", int_type_id, dspace_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
+    if(mindset_id < 0) TEST_ERROR
+
+    /********************
+     * TEST/DEMONSTRATE *
+     ********************/
+
+    /* -------------------
+     * no attributes added
+     */
+
+    count = count_attributes(dset_id);
+    if(count != 0) TEST_ERROR
+    count = count_attributes(mindset_id);
+    if(count != 0) TEST_ERROR
+
+    /* -----------------
+     * add one attribute
+     */
+    ret = put_attribute(dset_id, "PURPOSE", "DEMO", char_type_id, dspace_id, &attr_1_id);
+    if(ret < 0) TEST_ERROR
+
+    ret = put_attribute(mindset_id, "PURPOSE", "DEMO", char_type_id, dspace_id, &attr_1a_id);
+    if(ret < 0) TEST_ERROR
+
+    count = count_attributes(dset_id);
+    if(count != 1) TEST_ERROR
+    count = count_attributes(mindset_id);
+    if(count != 1) TEST_ERROR
+
+    ret = H5Aread(attr_1_id, char_type_id, buffer);
+    if(ret < 0) TEST_ERROR
+    if(HDstrcmp("DEMO", buffer)) TEST_ERROR
+
+    ret = H5Aread(attr_1a_id, char_type_id, buffer);
+    if(ret < 0) TEST_ERROR
+    if(HDstrcmp("DEMO", buffer)) TEST_ERROR
+
+    /* -----------------
+     * modify one attribute
+     */
+
+    ret = put_attribute(dset_id, "PURPOSE", "REWRITE", char_type_id, -1, &attr_1_id);
+    if(ret < 0) TEST_ERROR
+
+    ret = put_attribute(mindset_id, "PURPOSE", "REWRITE", char_type_id, -1, &attr_1a_id);
+    if(ret < 0) TEST_ERROR
+
+    count = count_attributes(dset_id);
+    if(count != 1) TEST_ERROR
+    count = count_attributes(mindset_id);
+    if(count != 1) TEST_ERROR
+
+    ret = H5Aread(attr_1_id, char_type_id, buffer);
+    if(ret < 0) TEST_ERROR
+    if(HDstrcmp("REWRITE", buffer)) TEST_ERROR
+
+    ret = H5Aread(attr_1a_id, char_type_id, buffer);
+    if(ret < 0) TEST_ERROR
+    if(HDstrcmp("REWRITE", buffer)) TEST_ERROR
+
+    /* -----------------
+     * add second attribute
+     */
+
+    a_out = 5;
+    ret = put_attribute(dset_id, "RANK", &a_out, int_type_id, dspace_scalar_id, &attr_2_id);
+    if(ret < 0) TEST_ERROR
+
+    a_out = 3;
+    ret = put_attribute(mindset_id, "RANK", &a_out, int_type_id, dspace_scalar_id, &attr_2a_id);
+    if(ret < 0) TEST_ERROR
+
+    count = count_attributes(dset_id);
+    if(count != 2) TEST_ERROR
+    count = count_attributes(mindset_id);
+    if(count != 2) TEST_ERROR
+
+    ret = H5Aread(attr_2_id, int_type_id, &a_out);
+    if(ret < 0) TEST_ERROR
+    if(a_out != 5) TEST_ERROR
+
+    ret = H5Aread(attr_2a_id, int_type_id, &a_out);
+    if(ret < 0) TEST_ERROR
+    if(a_out != 3) TEST_ERROR
+
+    /* -----------------
+     * add third attribute
+     */
+
+    a_out = -86;
+    ret = put_attribute(dset_id, "FLAVOR", &a_out, int_type_id, dspace_scalar_id, &attr_3_id);
+    if(ret < 0) TEST_ERROR
+
+    a_out = 2185;
+    ret = put_attribute(mindset_id, "FLAVOR", &a_out, int_type_id, dspace_scalar_id, &attr_3a_id);
+    if(ret < 0) TEST_ERROR
+
+    count = count_attributes(dset_id);
+    if(count != 3) TEST_ERROR
+    count = count_attributes(mindset_id);
+    if(count != 3) TEST_ERROR
+
+    ret = H5Aread(attr_3_id, int_type_id, &a_out);
+    if(ret < 0) TEST_ERROR
+    if(a_out != -86) TEST_ERROR
+
+    ret = H5Aread(attr_3a_id, int_type_id, &a_out);
+    if(ret < 0) TEST_ERROR
+    if(a_out != 2185) TEST_ERROR
+
+    /************
+     * TEARDOWN *
+     ************/
+
+    if(H5Tclose(int_type_id) < 0) TEST_ERROR
+    if(H5Tclose(char_type_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_id) < 0) TEST_ERROR
+    if(H5Sclose(dspace_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_id) < 0) TEST_ERROR
+    if(H5Dclose(mindset_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_1_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_1a_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_2_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_2a_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_3_id) < 0) TEST_ERROR
+    if(H5Aclose(attr_3a_id) < 0) TEST_ERROR
+    if(H5Fclose(file_id) < 0) TEST_ERROR
+
+    PASSED()
+    return SUCCEED;
+
+error :
+    H5E_BEGIN_TRY {
+        (void)H5Tclose(int_type_id);
+        (void)H5Tclose(char_type_id);
+        (void)H5Pclose(dcpl_id);
+        (void)H5Sclose(dspace_id);
+        (void)H5Dclose(dset_id);
+        (void)H5Dclose(mindset_id);
+        (void)H5Aclose(attr_1_id);
+        (void)H5Aclose(attr_1a_id);
+        (void)H5Aclose(attr_2_id);
+        (void)H5Aclose(attr_2a_id);
+        (void)H5Aclose(attr_3_id);
+        (void)H5Aclose(attr_3a_id);
+        (void)H5Fclose(file_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* test_minimized_dset_ohdr_attribute_addition */
+
+/*
+ * Compare header sizes against when headers have been minimized.
+ * Repeats tests with headers "compact" and normal.
+ */
+static herr_t
+test_minimized_dset_ohdr_size_comparisons(hid_t fapl_id)
+{
+    hsize_t  array_10[1] = {10}; /* dataspace extents */
+    unsigned compact     = 0;
+
+    /* IDs that are file-agnostic */
+    hid_t dspace_id     = -1;
+    hid_t int_type_id   = -1;
+    hid_t dcpl_minimize = -1;
+    hid_t dcpl_dontmin  = -1;
+    hid_t dcpl_default  = -1;
+
+    /* IDs for non-minimized file open */
+    hid_t file_f_id   = -1; /* lower 'f' for standard file setting */
+    hid_t dset_f_x_id = -1; /* 'x' for default */
+    hid_t dset_f_N_id = -1; /* 'N' for explcit non-minimized dset */
+    hid_t dset_f_Y_id = -1; /* 'Y' for minimized dset */
+
+    /* IDs for minimized file open */
+    hid_t file_F_id   = -1; /* upper 'F' for minimized file setting */
+    hid_t dset_F_x_id = -1; /* 'x' for default */
+    hid_t dset_F_N_id = -1; /* 'N' for explcit non-minimized dset */
+    hid_t dset_F_Y_id = -1; /* 'Y' for minimized dset */
+
+    char filename_a[512] = "";
+    char filename_b[512] = "";
+
+    herr_t ret;
+
+    /* dataset suffixes:
+     *                | default | minimize | don't minimize (dcpl-set)
+     * ---------------+---------+----------+---------------
+     * file-default   |   f_x   |   f_Y    |   f_N
+     * ---------------+---------+----------+---------------
+     * file-minimized |   F_x   |   F_Y    |   F_N
+     */
+
+    TESTING("minimized dset object headers size comparisons");
+
+    /*********
+     * SETUP *
+     *********/
+
+    if(h5_fixname(FILENAME[1], H5P_DEFAULT, filename_a, sizeof(filename_a)) == NULL)
+        TEST_ERROR
+
+    if(h5_fixname(FILENAME[2], H5P_DEFAULT, filename_b, sizeof(filename_b)) == NULL)
+        TEST_ERROR
+
+    for (compact = 0; compact < 2; compact++) { /* 0 or 1 */
+        dcpl_default = H5Pcreate(H5P_DATASET_CREATE);
+        if(dcpl_default < 0) TEST_ERROR
+ 
+        dcpl_minimize = H5Pcreate(H5P_DATASET_CREATE);
+        if(dcpl_minimize < 0) TEST_ERROR
+        ret = H5Pset_dset_no_attrs_hint(dcpl_minimize, TRUE);
+        if(ret < 0) TEST_ERROR
+
+        dcpl_dontmin = H5Pcreate(H5P_DATASET_CREATE);
+        if(dcpl_dontmin < 0) TEST_ERROR
+        ret = H5Pset_dset_no_attrs_hint(dcpl_dontmin, FALSE);
+        if(ret < 0) TEST_ERROR
+
+        if(compact) {
+            HDprintf("...compact ");
+            ret = H5Pset_layout(dcpl_default, H5D_COMPACT);
+            if(ret < 0) TEST_ERROR
+            ret = H5Pset_layout(dcpl_minimize, H5D_COMPACT);
+            if(ret < 0) TEST_ERROR
+            ret = H5Pset_layout(dcpl_dontmin, H5D_COMPACT);
+            if(ret < 0) TEST_ERROR
+        } else 
+            HDprintf("...not compact ");
+
+        dspace_id = H5Screate_simple(1, array_10, NULL);
+        if(dspace_id < 0) TEST_ERROR
+
+        int_type_id = H5Tcopy(H5T_NATIVE_INT);
+        if(int_type_id < 0) TEST_ERROR
+
+        file_f_id = H5Fcreate(filename_a, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+        if(file_f_id < 0) TEST_ERROR
+
+        dset_f_x_id = H5Dcreate(file_f_id, "default", int_type_id, dspace_id, H5P_DEFAULT, dcpl_default, H5P_DEFAULT);
+        if(dset_f_x_id < 0) TEST_ERROR
+
+        dset_f_N_id = H5Dcreate(file_f_id, "dsetNOT", int_type_id, dspace_id, H5P_DEFAULT, dcpl_dontmin, H5P_DEFAULT);
+        if(dset_f_N_id < 0) TEST_ERROR
+
+        dset_f_Y_id = H5Dcreate(file_f_id, "dsetMIN", int_type_id, dspace_id, H5P_DEFAULT, dcpl_minimize, H5P_DEFAULT);
+        if(dset_f_x_id < 0) TEST_ERROR
+
+        file_F_id = H5Fcreate(filename_b, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+        if(file_F_id < 0) TEST_ERROR
+        ret = H5Fset_dset_no_attrs_hint(file_F_id, TRUE);
+        if(ret < 0) TEST_ERROR
+
+        dset_F_x_id = H5Dcreate(file_F_id, "default", int_type_id, dspace_id, H5P_DEFAULT, dcpl_default, H5P_DEFAULT);
+        if(dset_F_x_id < 0) TEST_ERROR
+
+        dset_F_N_id = H5Dcreate(file_F_id, "dsetNOT", int_type_id, dspace_id, H5P_DEFAULT, dcpl_dontmin, H5P_DEFAULT);
+        if(dset_F_N_id < 0) TEST_ERROR
+
+        dset_F_Y_id = H5Dcreate(file_F_id, "dsetMIN", int_type_id, dspace_id, H5P_DEFAULT, dcpl_minimize, H5P_DEFAULT);
+        if(dset_F_Y_id < 0) TEST_ERROR
+
+        /*********
+         * TESTS *
+         *********/
+
+        if(oh_compare(dset_f_x_id, dset_f_x_id) != EQ) TEST_ERROR /* identity */
+
+        if(oh_compare(dset_f_x_id, dset_f_N_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_f_x_id, dset_f_Y_id) != GT) TEST_ERROR
+        if(oh_compare(dset_f_N_id, dset_f_Y_id) != GT) TEST_ERROR
+
+        if(oh_compare(dset_F_x_id, dset_F_N_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_F_x_id, dset_F_Y_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_F_N_id, dset_F_Y_id) != EQ) TEST_ERROR
+
+        if(oh_compare(dset_F_x_id, dset_f_Y_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_F_x_id, dset_f_x_id) != LT) TEST_ERROR
+
+        /************
+         * TEARDOWN *
+         ************/
+
+        if(H5Sclose(dspace_id) < 0) TEST_ERROR
+        if(H5Tclose(int_type_id) < 0) TEST_ERROR
+        if(H5Pclose(dcpl_default) < 0) TEST_ERROR
+        if(H5Pclose(dcpl_minimize) < 0) TEST_ERROR
+        if(H5Pclose(dcpl_dontmin) < 0) TEST_ERROR
+
+        if(H5Fclose(file_f_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_f_x_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_f_N_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_f_Y_id) < 0) TEST_ERROR
+
+        if(H5Fclose(file_F_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_F_x_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_F_N_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_F_Y_id) < 0) TEST_ERROR
+
+    } /* compact and non-compact */
+
+    PASSED()
+    return SUCCEED;
+
+error :
+    H5E_BEGIN_TRY {
+        (void)H5Pclose(dcpl_default);
+        (void)H5Pclose(dcpl_minimize);
+        (void)H5Pclose(dcpl_dontmin);
+        (void)H5Sclose(dspace_id);
+        (void)H5Tclose(int_type_id);
+
+        (void)H5Fclose(file_f_id);
+        (void)H5Dclose(dset_f_x_id);
+        (void)H5Dclose(dset_f_N_id);
+        (void)H5Dclose(dset_f_Y_id);
+
+        (void)H5Fclose(file_F_id);
+        (void)H5Dclose(dset_F_x_id);
+        (void)H5Dclose(dset_F_N_id);
+        (void)H5Dclose(dset_F_Y_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* test_minimized_dset_ohdr_size_comparisons */
+
+/*
+ * Test minimized dataset object header with filter/pipeline message
+ */
+static herr_t
+test_minimized_dset_ohdr_with_filter(hid_t fapl_id)
+{
+    char           filename[512]   = "";
+    const hsize_t  extents[1]      = {1024}; /* extents of dataspace */
+    const unsigned filter_values[] = {0};  /* TBD */
+    const hsize_t  chunk_dim[]     = {32};  /* needed for filter */
+    const int      ndims           = 1;
+    hid_t          dspace_id       = -1;
+    hid_t          dtype_id        = -1;
+    hid_t          dcpl_xZ_id      = -1;
+    hid_t          dcpl_mx_id      = -1;
+    hid_t          dcpl_mZ_id      = -1;
+    hid_t          dset_xx_id      = -1;
+    hid_t          dset_xZ_id      = -1;
+    hid_t          dset_mx_id      = -1;
+    hid_t          dset_mZ_id      = -1;
+    hid_t          file_id         = -1;
+    herr_t         ret;
+
+    /* dcpl suffixes:
+     *           | default | minimize
+     * ----------+---------+---------
+     * no filter |    xx   |   mx
+     * ----------+---------+---------
+     * filter    |    xZ   |   mZ
+     */
+
+    TESTING("minimized dset object headers with filter message");
+
+    /*********
+     * SETUP *
+     *********/
+
+    if(h5_fixname(FILENAME[1], H5P_DEFAULT, filename, sizeof(filename)) == NULL)
+        TEST_ERROR
+
+    dcpl_mx_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_mx_id < 0) TEST_ERROR
+    ret = H5Pset_dset_no_attrs_hint(dcpl_mx_id, TRUE);
+    if(ret < 0) TEST_ERROR
+
+    dcpl_xZ_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_xZ_id < 0) TEST_ERROR
+    ret = H5Pset_chunk(dcpl_xZ_id, ndims, chunk_dim);
+    if(ret < 0) TEST_ERROR
+    ret = H5Pset_filter(dcpl_xZ_id, H5Z_FILTER_DEFLATE, H5Z_FLAG_OPTIONAL, 0, filter_values);
+    if(ret < 0) TEST_ERROR
+    dcpl_mZ_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_mZ_id < 0) TEST_ERROR
+    ret = H5Pset_dset_no_attrs_hint(dcpl_mZ_id, TRUE);
+    if(ret < 0) TEST_ERROR
+    ret = H5Pset_chunk(dcpl_mZ_id, ndims, chunk_dim);
+    if(ret < 0) TEST_ERROR
+    ret = H5Pset_filter( dcpl_mZ_id, H5Z_FILTER_DEFLATE, H5Z_FLAG_OPTIONAL, 0, filter_values);
+    if(ret < 0) TEST_ERROR
+
+    dspace_id = H5Screate_simple(1, extents, extents);
+    if(dspace_id < 0) TEST_ERROR
+
+    dtype_id = H5Tcopy(H5T_NATIVE_INT);
+    if(dtype_id < 0) TEST_ERROR
+
+    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if(file_id < 0) TEST_ERROR
+
+    dset_xx_id = H5Dcreate(file_id, "xx", dtype_id, dspace_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    if(dset_xx_id < 0) TEST_ERROR
+
+    dset_mx_id = H5Dcreate(file_id, "Mx", dtype_id, dspace_id, H5P_DEFAULT, dcpl_mx_id, H5P_DEFAULT);
+    if(dset_mx_id < 0) TEST_ERROR
+
+    dset_xZ_id = H5Dcreate(file_id, "xZ", dtype_id, dspace_id, H5P_DEFAULT, dcpl_xZ_id, H5P_DEFAULT);
+    if(dset_xZ_id < 0) TEST_ERROR
+
+    dset_mZ_id = H5Dcreate(file_id, "MZ", dtype_id, dspace_id, H5P_DEFAULT, dcpl_mZ_id, H5P_DEFAULT);
+    if(dset_mZ_id < 0) TEST_ERROR
+
+    /*********
+     * TESTS *
+     *********/
+
+    if(oh_compare(dset_mx_id, dset_xx_id) != LT) TEST_ERROR
+    if(oh_compare(dset_mx_id, dset_xZ_id) != LT) TEST_ERROR
+    if(oh_compare(dset_mZ_id, dset_mx_id) != GT) TEST_ERROR
+    if(oh_compare(dset_mZ_id, dset_xZ_id) != LT) TEST_ERROR
+
+    /************
+     * TEARDOWN *
+     ************/
+
+    if(H5Sclose(dspace_id) < 0) TEST_ERROR
+    if(H5Tclose(dtype_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_xZ_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_mx_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_mZ_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_xx_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_xZ_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_mx_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_mZ_id) < 0) TEST_ERROR
+    if(H5Fclose(file_id) < 0) TEST_ERROR
+
+    PASSED()
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        (void)H5Sclose(dspace_id);
+        (void)H5Tclose(dtype_id);
+        (void)H5Pclose(dcpl_xZ_id);
+        (void)H5Pclose(dcpl_mx_id);
+        (void)H5Pclose(dcpl_mZ_id);
+        (void)H5Dclose(dset_xx_id);
+        (void)H5Dclose(dset_xZ_id);
+        (void)H5Dclose(dset_mx_id);
+        (void)H5Dclose(dset_mZ_id);
+        (void)H5Fclose(file_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* test_minimized_dset_ohdr_with_filter */
+
+/*
+ * Test minimized dataset object header and recording modification times.
+ */
+static herr_t
+test_minimized_dset_ohdr_modification_times(hid_t _fapl_id)
+{
+    /* test-local structure for parameterized testing
+     */
+    struct testcase {
+        unsigned oh_version;
+    };
+
+    char          filename[512] = "";
+    const hsize_t extents[1]    = {128}; /* extents of dataspace */
+    hid_t         dspace_id     = -1;
+    hid_t         dtype_id      = -1;
+    hid_t         dcpl_xT_id    = -1; /* Track modtime */
+    hid_t         dcpl_mx_id    = -1; /* minimized */
+    hid_t         dcpl_mT_id    = -1; /* minimized, Track */
+    hid_t         dcpl_mN_id    = -1; /* minimized, do Not track */
+    hid_t         dset_xx_id    = -1;
+    hid_t         dset_xT_id    = -1;
+    hid_t         dset_mx_id    = -1;
+    hid_t         dset_mT_id    = -1;
+    hid_t         dset_mN_id    = -1;
+    hid_t         file_id       = -1;
+    hid_t         fapl_id       = -1;
+    herr_t        ret;
+
+    unsigned i       = 0; /* for testcase loop */
+    unsigned n_cases = 2; /* must match `cases` array size below */
+    struct testcase cases[2] = {
+        { 1, }, /* version 1 object header */
+        { 2, }, /* version 2 object header */
+    };
+
+    /* dcpl suffixes:
+     *             | default | minimize
+     * ------------+---------+---------
+     * default     |    xx   |   mx
+     * ------------+---------+---------
+     * don't track |    xN   |   mN
+     * ------------+---------+---------
+     * track       |    xT   |   mT
+     */
+
+    TESTING("minimized dset object headers with modification times");
+
+    /*********
+     * SETUP *
+     *********/
+
+    if(h5_fixname(FILENAME[1], H5P_DEFAULT, filename, sizeof(filename)) == NULL)
+        TEST_ERROR
+
+    dcpl_mx_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_mx_id < 0) TEST_ERROR
+    ret = H5Pset_dset_no_attrs_hint(dcpl_mx_id, TRUE);
+    if(ret < 0) TEST_ERROR
+
+    dcpl_xT_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_xT_id < 0) TEST_ERROR
+    ret = H5Pset_obj_track_times(dcpl_xT_id, TRUE);
+    if(ret < 0) TEST_ERROR
+
+    dcpl_mT_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_mT_id < 0) TEST_ERROR
+    ret = H5Pset_dset_no_attrs_hint(dcpl_mT_id, TRUE);
+    if(ret < 0) TEST_ERROR
+    ret = H5Pset_obj_track_times(dcpl_mT_id, TRUE);
+    if(ret < 0) TEST_ERROR
+
+    dcpl_mN_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_mN_id < 0) TEST_ERROR
+    ret = H5Pset_dset_no_attrs_hint(dcpl_mN_id, TRUE);
+    if(ret < 0) TEST_ERROR
+    ret = H5Pset_obj_track_times(dcpl_mN_id, FALSE);
+    if(ret < 0) TEST_ERROR
+
+    dspace_id = H5Screate_simple(1, extents, extents);
+    if(dspace_id < 0) TEST_ERROR
+
+    dtype_id = H5Tcopy(H5T_NATIVE_INT);
+    if(dtype_id < 0) TEST_ERROR
+
+    for (i = 0; i < n_cases; i++) {
+
+        /* -------------- *
+         * per-case setup *
+         * -------------- */
+
+        fapl_id = H5Pcopy(_fapl_id);
+        if(fapl_id < 0) TEST_ERROR
+
+        if(cases[i].oh_version > 1) {
+            fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+            if(fapl_id < 0) TEST_ERROR
+            ret = H5Pset_libver_bounds(fapl_id, H5F_LIBVER_V18, H5F_LIBVER_V110);
+            if(ret < 0) TEST_ERROR
+        }
+
+        file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+        if(file_id < 0) TEST_ERROR
+
+        dset_xx_id = H5Dcreate( file_id, "xx", dtype_id, dspace_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+        if(dset_xx_id < 0) TEST_ERROR
+
+        dset_mx_id = H5Dcreate(file_id, "mx", dtype_id, dspace_id, H5P_DEFAULT, dcpl_mx_id, H5P_DEFAULT);
+        if(dset_mx_id < 0) TEST_ERROR
+
+        dset_xT_id = H5Dcreate(file_id, "xT", dtype_id, dspace_id, H5P_DEFAULT, dcpl_xT_id, H5P_DEFAULT);
+        if(dset_xT_id < 0) TEST_ERROR
+        dset_mT_id = H5Dcreate(file_id, "mT", dtype_id, dspace_id, H5P_DEFAULT, dcpl_mT_id, H5P_DEFAULT);
+        if(dset_mT_id < 0) TEST_ERROR
+
+        dset_mN_id = H5Dcreate(file_id, "mN", dtype_id, dspace_id, H5P_DEFAULT, dcpl_mN_id, H5P_DEFAULT);
+        if(dset_mN_id < 0) TEST_ERROR
+
+        /* ----- *
+         * TESTS *
+         * ----- */
+
+        /* sanity check */
+        if(oh_compare(dset_mx_id, dset_xx_id) != LT) TEST_ERROR
+        if(oh_compare(dset_mx_id, dset_xT_id) != LT) TEST_ERROR
+
+        if(oh_compare(dset_xx_id, dset_xT_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_mx_id, dset_mT_id) != EQ) TEST_ERROR
+        if(oh_compare(dset_mN_id, dset_mT_id) != LT) TEST_ERROR
+
+        if(oh_compare(dset_mT_id, dset_xT_id) != LT) TEST_ERROR
+
+        /* ----------------- *
+         * per-case teardown *
+         * ----------------- */
+
+        if(H5Dclose(dset_xx_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_xT_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_mx_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_mT_id) < 0) TEST_ERROR
+        if(H5Dclose(dset_mN_id) < 0) TEST_ERROR
+        if(H5Fclose(file_id) < 0) TEST_ERROR
+        if(H5Pclose(fapl_id) < 0) TEST_ERROR
+
+    } /* for each version tested */
+
+    /************
+     * TEARDOWN *
+     ************/
+
+    if(H5Sclose(dspace_id) < 0) TEST_ERROR
+    if(H5Tclose(dtype_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_xT_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_mx_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_mT_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_mN_id) < 0) TEST_ERROR
+
+    PASSED()
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        (void)H5Sclose(dspace_id);
+        (void)H5Tclose(dtype_id);
+        (void)H5Pclose(dcpl_xT_id);
+        (void)H5Pclose(dcpl_mx_id);
+        (void)H5Pclose(dcpl_mT_id);
+        (void)H5Pclose(dcpl_mN_id);
+        (void)H5Dclose(dset_xx_id);
+        (void)H5Dclose(dset_xT_id);
+        (void)H5Dclose(dset_mx_id);
+        (void)H5Dclose(dset_mT_id);
+        (void)H5Dclose(dset_mN_id);
+        (void)H5Fclose(file_id);
+        (void)H5Pclose(fapl_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* test_minimized_dset_ohdr_modification_times */
+
+/*
+ * Test minimized dataset object header with a fill value set.
+ */
+static herr_t
+test_minimized_dset_ohdr_fillvalue_backwards_compatability(hid_t _fapl_id)
+{
+    char          filename[512] = "";
+    const hsize_t extents[1]    = {64}; /* extents of dataspace */
+    const int     fill[1]       = {343}; /* fill value of dataset */
+    hid_t         file_id       = -1;
+    hid_t         dtype_id      = -1;
+    hid_t         dspace_id     = -1;
+    hid_t         dcpl_id       = -1;
+    hid_t         fapl_id       = -1;
+    hid_t         dset_0_id     = -1;
+    hid_t         dset_1_id     = -1;
+    herr_t        ret;
+
+    /*********
+     * SETUP *
+     *********/
+
+    TESTING("minimized dset object headers with fill values and different libver support");
+
+    if(h5_fixname(FILENAME[1], H5P_DEFAULT, filename, sizeof(filename)) == NULL)
+        TEST_ERROR
+
+    dspace_id = H5Screate_simple(1, extents, extents);
+    if(dspace_id < 0) TEST_ERROR
+
+    dtype_id = H5Tcopy(H5T_NATIVE_INT);
+    if(dtype_id < 0) TEST_ERROR
+
+    dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
+    if(dcpl_id < 0) TEST_ERROR
+
+    ret = H5Pset_dset_no_attrs_hint(dcpl_id, TRUE);
+    if(ret == FAIL) TEST_ERROR;
+
+    ret = H5Pset_fill_value(dcpl_id, dtype_id, fill);
+    if(ret == FAIL) TEST_ERROR;
+
+    fapl_id = H5Pcopy(_fapl_id);
+    if(fapl_id < 0) TEST_ERROR
+
+    ret = H5Pset_libver_bounds(fapl_id, H5F_LIBVER_EARLIEST, H5F_LIBVER_LATEST);
+    if(ret == FAIL) TEST_ERROR;
+
+    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if(file_id < 0) TEST_ERROR
+
+    dset_0_id = H5Dcreate(file_id, "fullrange", dtype_id, dspace_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
+    if(dset_0_id < 0) TEST_ERROR
+
+    /* Close file and re-open with different libver bounds.
+     * Dataset "fullrange" must also be closed for expected reopen behavior.
+     */
+    if(H5Fclose(file_id) < 0) TEST_ERROR;
+    if(H5Dclose(dset_0_id) < 0) TEST_ERROR
+
+    ret = H5Pset_libver_bounds(fapl_id, H5F_LIBVER_V18, H5F_LIBVER_LATEST);
+    if(ret == FAIL) TEST_ERROR;
+
+    file_id = H5Fopen(filename, H5F_ACC_RDWR, fapl_id);
+    if(file_id < 0) TEST_ERROR
+
+    dset_1_id = H5Dcreate(file_id, "upperrange", dtype_id, dspace_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
+    if(dset_1_id < 0) TEST_ERROR
+
+    /* re-open "fullrange" dataset
+     */
+     dset_0_id = H5Dopen2(file_id, "fullrange", H5P_DEFAULT);
+     if(dset_0_id < 0) TEST_ERROR
+
+    /*********
+     * TESTS *
+     *********/
+
+    /* dset not supporting pre-1.08 should be smaller? */
+    if(oh_compare(dset_1_id, dset_0_id) != LT) TEST_ERROR
+
+    /************
+     * TEARDOWN *
+     ************/
+
+    if(H5Sclose(dspace_id) < 0) TEST_ERROR
+    if(H5Tclose(dtype_id) < 0) TEST_ERROR
+    if(H5Pclose(dcpl_id) < 0) TEST_ERROR
+    if(H5Pclose(fapl_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_0_id) < 0) TEST_ERROR
+    if(H5Dclose(dset_1_id) < 0) TEST_ERROR
+    if(H5Fclose(file_id) < 0) TEST_ERROR;
+
+    PASSED()
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        (void)H5Sclose(dspace_id);
+        (void)H5Tclose(dtype_id);
+        (void)H5Pclose(dcpl_id);
+        (void)H5Pclose(fapl_id);
+        (void)H5Dclose(dset_0_id);
+        (void)H5Dclose(dset_1_id);
+        (void)H5Fclose(file_id);
+    } H5E_END_TRY;
+    return FAIL;
+} /* test_minimized_dset_ohdr_fillvalue_backwards_compatability */
+
 #define STR_EARLIEST "earliest"
 #define STR_V18 "v18"
 #define STR_LATEST "latest"
@@ -1030,6 +1916,21 @@ main(void)
         if(test_ohdr_cache(filename, fapl) < 0)
             TEST_ERROR
 
+        if(test_minimized_dset_ohdr_attribute_addition(fapl) < 0)
+            TEST_ERROR
+
+        if(test_minimized_dset_ohdr_size_comparisons(fapl) < 0)
+            TEST_ERROR
+
+        if(test_minimized_dset_ohdr_with_filter(fapl) < 0)
+            TEST_ERROR
+
+        if(test_minimized_dset_ohdr_modification_times(fapl) < 0)
+            TEST_ERROR
+
+        if(test_minimized_dset_ohdr_fillvalue_backwards_compatability(fapl) < 0)
+            TEST_ERROR
+
       } /* high */
     } /* low */
 
diff --git a/test/tattr.c b/test/tattr.c
index 9d80050..c1167c6 100644
--- a/test/tattr.c
+++ b/test/tattr.c
@@ -165,6 +165,12 @@ typedef struct {
 static herr_t attr_op1(hid_t loc_id, const char *name, const H5A_info_t *ainfo,
     void *op_data);
 
+/* Global dcpl ID, can be re-set as a generated dcpl for various operations
+ * across multiple tests.
+ * e.g., minimized dataset object headers
+ */
+static hid_t dcpl_g = H5P_DEFAULT;
+
 
 
 /****************************************************************
@@ -204,7 +210,7 @@ test_attr_basic_write(hid_t fapl)
     CHECK(sid1, FAIL, "H5Screate_simple");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Create dataspace for attribute */
@@ -524,7 +530,7 @@ test_attr_flush(hid_t fapl)
     spc = H5Screate(H5S_SCALAR);
     CHECK(spc, FAIL, "H5Screate");
 
-    set = H5Dcreate2(fil, DSET1_NAME, H5T_NATIVE_DOUBLE, spc, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    set = H5Dcreate2(fil, DSET1_NAME, H5T_NATIVE_DOUBLE, spc, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(set, FAIL, "H5Dcreate2");
 
     att = H5Acreate2(set, ATTR1_NAME, H5T_NATIVE_DOUBLE, spc, H5P_DEFAULT, H5P_DEFAULT);
@@ -595,7 +601,7 @@ test_attr_plist(hid_t fapl)
     CHECK(sid1, FAIL, "H5Screate_simple");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Create dataspace for attribute */
@@ -709,7 +715,7 @@ test_attr_compound_write(hid_t fapl)
     CHECK(sid1, FAIL, "H5Screate_simple");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Close dataset's dataspace */
@@ -945,7 +951,7 @@ test_attr_scalar_write(hid_t fapl)
     CHECK(sid1, FAIL, "H5Screate_simple");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Create dataspace for attribute */
@@ -1086,7 +1092,7 @@ test_attr_mult_write(hid_t fapl)
     CHECK(sid1, FAIL, "H5Screate_simple");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Close dataset's dataspace */
@@ -1464,7 +1470,7 @@ test_attr_iterate(hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create a new dataset */
-    dataset = H5Dcreate2(file, DSET2_NAME, H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(file, DSET2_NAME, H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Close dataspace */
@@ -1688,7 +1694,7 @@ test_attr_dtype_shared(hid_t fapl)
     CHECK(space_id, FAIL, "H5Screate");
 
     /* Create dataset */
-    dset_id = H5Dcreate2(file_id, DSET1_NAME, type_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dset_id = H5Dcreate2(file_id, DSET1_NAME, type_id, space_id, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dset_id, FAIL, "H5Dcreate2");
 
     /* Check reference count on named datatype */
@@ -1842,7 +1848,7 @@ test_attr_duplicate_ids(hid_t fapl)
 
     /* Create a dataset */
     dataset = H5Dcreate2(fid1, DSET1_NAME, H5T_NATIVE_UCHAR, sid1, H5P_DEFAULT,
-            H5P_DEFAULT, H5P_DEFAULT);
+            dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
     /* Create dataspace for attribute */
@@ -2167,9 +2173,14 @@ test_attr_dense_create(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Create a dataset */
     dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -2298,9 +2309,14 @@ test_attr_dense_open(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Enable creation order tracking on attributes, so creation order tests work */
     ret = H5Pset_attr_creation_order(dcpl, H5P_CRT_ORDER_TRACKED);
@@ -2412,14 +2428,25 @@ test_attr_dense_delete(hid_t fcpl, hid_t fapl)
     h5_stat_size_t empty_filesize;       /* Size of empty file */
     h5_stat_size_t filesize;             /* Size of file after modifications */
     H5O_info_t  oinfo;          /* Object info                  */
+    int         use_min_dset_oh = (dcpl_g != H5P_DEFAULT);
     herr_t      ret;            /* Generic return value        */
 
     /* Output message about test being performed */
     MESSAGE(5, ("Testing Deleting Attributes in Dense Storage\n"));
 
-    /* Create file */
+    if (use_min_dset_oh) { /* using minimized dataset headers */
+        /* modify fcpl...
+         * sidestep "bug" where file space is lost with minimized dset ohdrs
+         */
+        fcpl = H5Pcopy(fcpl);
+        CHECK(fcpl, FAIL, "H5Pcopy");
+        ret = H5Pset_file_space_strategy(fcpl, H5F_FSPACE_STRATEGY_FSM_AGGR, TRUE, 1);
+        CHECK(ret, FAIL, "H5Pset_file_space_strategy");
+    }
     fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl, fapl);
     CHECK(fid, FAIL, "H5Fcreate");
+    if (use_min_dset_oh)
+        CHECK(H5Pclose(fcpl), FAIL, "H5Pclose");
 
     /* Close file */
     ret = H5Fclose(fid);
@@ -2438,9 +2465,14 @@ test_attr_dense_delete(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (use_min_dset_oh) {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    } else {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    }
 
     /* Enable creation order tracking on attributes, so creation order tests work */
     ret = H5Pset_attr_creation_order(dcpl, H5P_CRT_ORDER_TRACKED);
@@ -2591,14 +2623,25 @@ test_attr_dense_rename(hid_t fcpl, hid_t fapl)
     h5_stat_size_t filesize;             /* Size of file after modifications */
     H5O_info_t  oinfo;          /* Object info */
     unsigned    u;              /* Local index variable */
+    int         use_min_dset_oh = (dcpl_g != H5P_DEFAULT);
     herr_t      ret;            /* Generic return value        */
 
     /* Output message about test being performed */
     MESSAGE(5, ("Testing Renaming Attributes in Dense Storage\n"));
 
-    /* Create file */
+    if (use_min_dset_oh) { /* using minimized dataset headers */
+        /* modify fcpl...
+         * sidestep "bug" where file space is lost with minimized dset ohdrs
+         */
+        fcpl = H5Pcopy(fcpl);
+        CHECK(fcpl, FAIL, "H5Pcopy");
+        ret = H5Pset_file_space_strategy(fcpl, H5F_FSPACE_STRATEGY_FSM_AGGR, TRUE, 1);
+        CHECK(ret, FAIL, "H5Pset_file_space_strategy");
+    }
     fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl, fapl);
     CHECK(fid, FAIL, "H5Fcreate");
+    if (use_min_dset_oh)
+        CHECK(H5Pclose(fcpl), FAIL, "H5Pclose");
 
     /* Close file */
     ret = H5Fclose(fid);
@@ -2617,9 +2660,14 @@ test_attr_dense_rename(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (use_min_dset_oh) {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    } else {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    }
 
     /* Create a dataset */
     dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -2750,20 +2798,29 @@ test_attr_dense_unlink(hid_t fcpl, hid_t fapl)
     h5_stat_size_t filesize;             /* Size of file after modifications */
     H5O_info_t  oinfo;          /* Object info */
     unsigned    u;              /* Local index variable */
+    int         use_min_dset_oh = (dcpl_g != H5P_DEFAULT);
     herr_t      ret;            /* Generic return value        */
 
     /* Output message about test being performed */
     MESSAGE(5, ("Testing Unlinking Object with Attributes in Dense Storage\n"));
 
-    /* Create file */
+    if (use_min_dset_oh) { /* using minimized dataset headers */
+        /* modify fcpl...
+         * sidestep "bug" where file space is lost with minimized dset ohdrs
+         */
+        fcpl = H5Pcopy(fcpl);
+        CHECK(fcpl, FAIL, "H5Pcopy");
+        ret = H5Pset_file_space_strategy(fcpl, H5F_FSPACE_STRATEGY_FSM_AGGR, TRUE, 1);
+        CHECK(ret, FAIL, "H5Pset_file_space_strategy");
+    }
     fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl, fapl);
     CHECK(fid, FAIL, "H5Fcreate");
+    if (use_min_dset_oh)
+        CHECK(H5Pclose(fcpl), FAIL, "H5Pclose");
 
-    /* Close file */
     ret = H5Fclose(fid);
     CHECK(ret, FAIL, "H5Fclose");
 
-    /* Get size of file */
     empty_filesize = h5_get_file_size(FILENAME, fapl);
     if(empty_filesize < 0)
         TestErrPrintf("Line %d: file size wrong!\n", __LINE__);
@@ -2776,9 +2833,14 @@ test_attr_dense_unlink(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (use_min_dset_oh) {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    } else {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    }
 
     /* Create a dataset */
     dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -2904,9 +2966,14 @@ test_attr_dense_limits(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Change limits on compact/dense attribute storage */
     max_compact = 0;
@@ -3071,9 +3138,14 @@ test_attr_dense_dup_ids(hid_t fcpl, hid_t fapl)
     sid = H5Screate(H5S_SCALAR);
     CHECK(sid, FAIL, "H5Screate");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Create a dataset */
     dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -3601,9 +3673,14 @@ test_attr_big(hid_t fcpl, hid_t fapl)
     big_sid = H5Screate_simple(ATTR6_RANK, dims, NULL);
     CHECK(big_sid, FAIL, "H5Screate_simple");
 
-    /* Query the group creation properties */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    /* need DCPL to query the group creation properties */
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Retrieve limits for compact/dense attribute storage */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -3868,7 +3945,7 @@ test_attr_null_space(hid_t fcpl, hid_t fapl)
     CHECK(null_sid, FAIL, "H5Screate");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
 
@@ -4061,7 +4138,7 @@ test_attr_deprec(hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create a dataset */
-    dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(dataset, FAIL, "H5Dcreate2");
 
 
@@ -4296,8 +4373,13 @@ test_attr_corder_create_basic(hid_t fcpl, hid_t fapl)
     CHECK(fid, FAIL, "H5Fcreate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Get creation order indexing on object */
     ret = H5Pget_attr_creation_order(dcpl, &crt_order_flags);
@@ -4419,8 +4501,13 @@ test_attr_corder_create_compact(hid_t fcpl, hid_t fapl)
     CHECK(fid, FAIL, "H5Fcreate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Set attribute creation order tracking & indexing for object */
     ret = H5Pset_attr_creation_order(dcpl, (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED));
@@ -4619,8 +4706,13 @@ test_attr_corder_create_dense(hid_t fcpl, hid_t fapl)
     CHECK(fid, FAIL, "H5Fcreate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Set attribute creation order tracking & indexing for object */
     ret = H5Pset_attr_creation_order(dcpl, (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED));
@@ -4954,8 +5046,13 @@ test_attr_corder_transition(hid_t fcpl, hid_t fapl)
     CHECK(fid, FAIL, "H5Fcreate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Set attribute creation order tracking & indexing for object */
     ret = H5Pset_attr_creation_order(dcpl, (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED));
@@ -5365,8 +5462,13 @@ test_attr_corder_delete(hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Set attribute creation order tracking & indexing for object */
     ret = H5Pset_attr_creation_order(dcpl, (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED));
@@ -5708,8 +5810,13 @@ test_attr_info_by_idx(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -6068,8 +6175,13 @@ test_attr_delete_by_idx(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -7011,8 +7123,13 @@ test_attr_iterate2(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -7372,8 +7489,13 @@ test_attr_open_by_idx(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -7719,8 +7841,13 @@ test_attr_open_by_name(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -7973,8 +8100,13 @@ test_attr_create_by_name(hbool_t new_format, hid_t fcpl, hid_t fapl)
     CHECK(sid, FAIL, "H5Screate");
 
     /* Create dataset creation property list */
-    dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    CHECK(dcpl, FAIL, "H5Pcreate");
+    if (dcpl_g == H5P_DEFAULT) {
+        dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        CHECK(dcpl, FAIL, "H5Pcreate");
+    } else {
+        dcpl = H5Pcopy(dcpl_g);
+        CHECK(dcpl, FAIL, "H5Pcopy");
+    }
 
     /* Query the attribute creation properties */
     ret = H5Pget_attr_phase_change(dcpl, &max_compact, &min_dense);
@@ -8274,8 +8406,13 @@ test_attr_shared_write(hid_t fcpl, hid_t fapl)
         } /* end if */
 
         /* Set up to query the object creation properties */
-        dcpl = H5Pcreate(H5P_DATASET_CREATE);
-        CHECK(dcpl, FAIL, "H5Pcreate");
+        if (dcpl_g == H5P_DEFAULT) {
+            dcpl = H5Pcreate(H5P_DATASET_CREATE);
+            CHECK(dcpl, FAIL, "H5Pcreate");
+        } else {
+            dcpl = H5Pcopy(dcpl_g);
+            CHECK(dcpl, FAIL, "H5Pcopy");
+        }
 
         /* Create datasets */
         dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -8605,8 +8742,13 @@ test_attr_shared_rename(hid_t fcpl, hid_t fapl)
         } /* end if */
 
         /* Set up to query the object creation properties */
-        dcpl = H5Pcreate(H5P_DATASET_CREATE);
-        CHECK(dcpl, FAIL, "H5Pcreate");
+        if (dcpl_g == H5P_DEFAULT) {
+            dcpl = H5Pcreate(H5P_DATASET_CREATE);
+            CHECK(dcpl, FAIL, "H5Pcreate");
+        } else {
+            dcpl = H5Pcopy(dcpl_g);
+            CHECK(dcpl, FAIL, "H5Pcopy");
+        }
 
         /* Create datasets */
         dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -9051,8 +9193,13 @@ test_attr_shared_delete(hid_t fcpl, hid_t fapl)
         } /* end if */
 
         /* Set up to query the object creation properties */
-        dcpl = H5Pcreate(H5P_DATASET_CREATE);
-        CHECK(dcpl, FAIL, "H5Pcreate");
+        if (dcpl_g == H5P_DEFAULT) {
+            dcpl = H5Pcreate(H5P_DATASET_CREATE);
+            CHECK(dcpl, FAIL, "H5Pcreate");
+        } else {
+            dcpl = H5Pcopy(dcpl_g);
+            CHECK(dcpl, FAIL, "H5Pcopy");
+        }
 
         /* Create datasets */
         dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -9420,8 +9567,13 @@ test_attr_shared_unlink(hid_t fcpl, hid_t fapl)
         } /* end if */
 
         /* Set up to query the object creation properties */
-        dcpl = H5Pcreate(H5P_DATASET_CREATE);
-        CHECK(dcpl, FAIL, "H5Pcreate");
+        if (dcpl_g == H5P_DEFAULT) {
+            dcpl = H5Pcreate(H5P_DATASET_CREATE);
+            CHECK(dcpl, FAIL, "H5Pcreate");
+        } else {
+            dcpl = H5Pcopy(dcpl_g);
+            CHECK(dcpl, FAIL, "H5Pcopy");
+        }
 
         /* Create datasets */
         dataset = H5Dcreate2(fid, DSET1_NAME, H5T_NATIVE_UCHAR, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT);
@@ -10012,7 +10164,7 @@ test_attr_bug3(hid_t fcpl, hid_t fapl)
     CHECK(ret, FAIL, "H5Tcommit2");
 
     /* Create dataset */
-    did = H5Dcreate2(fid, "dset", tid2, sid2, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did = H5Dcreate2(fid, "dset", tid2, sid2, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(did, FAIL, "H5Dcreate2");
 
     /* Create attribute on datatype, using that datatype as its datatype */
@@ -10147,7 +10299,7 @@ test_attr_bug4(hid_t fcpl, hid_t fapl)
     CHECK(ret, FAIL, "H5Tcommit2");
 
     /* Create dataset */
-    did = H5Dcreate2(fid, "dset", tid, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did = H5Dcreate2(fid, "dset", tid, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(did, FAIL, "H5Dcreate2");
 
     /* Create attributes on group and dataset */
@@ -10229,7 +10381,7 @@ test_attr_bug5(hid_t fcpl, hid_t fapl)
     CHECK(ret, FAIL, "H5Tcommit2");
 
     /* Create dataset */
-    did1 = H5Dcreate2(fid1, BUG3_DSET_NAME, tid1, sid, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did1 = H5Dcreate2(fid1, BUG3_DSET_NAME, tid1, sid, H5P_DEFAULT, dcpl_g, H5P_DEFAULT);
     CHECK(did1, FAIL, "H5Dcreate2");
 
     /* Create attribute on root group */
@@ -10927,105 +11079,96 @@ test_attr(void)
 {
     hid_t    fapl = (-1), fapl2 = (-1);    /* File access property lists */
     hid_t    fcpl = (-1), fcpl2 = (-1);    /* File creation property lists */
-    unsigned new_format;        /* Whether to use the new format or not */
-    unsigned use_shared;        /* Whether to use shared attributes or not */
-    herr_t ret;                 /* Generic return value */
+    hid_t    dcpl = -1;
+    unsigned new_format;       /* Whether to use the new format or not */
+    unsigned use_shared;       /* Whether to use shared attributes or not */
+    unsigned minimize_dset_oh; /* Whether to use minimized dataset object headers */
+    herr_t ret;                /* Generic return value */
 
-    /* Output message about test being performed */
     MESSAGE(5, ("Testing Attributes\n"));
 
-    /* Create a default file access property list */
     fapl = H5Pcreate(H5P_FILE_ACCESS);
     CHECK(fapl, FAIL, "H5Pcreate");
 
-    /* Copy the file access property list */
     fapl2 = H5Pcopy(fapl);
     CHECK(fapl2, FAIL, "H5Pcopy");
-
-    /* Set the "use the latest version of the format" bounds for creating objects in the file */
     ret = H5Pset_libver_bounds(fapl2, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST);
     CHECK(ret, FAIL, "H5Pset_libver_bounds");
 
-    /* Create a default file creation property list */
     fcpl = H5Pcreate(H5P_FILE_CREATE);
     CHECK(fcpl, FAIL, "H5Pcreate");
 
-    /* Copy the file creation property list */
+    /* files with fcpl2 make all attributes ( > 1 byte) shared
+     * (i.e. all of them :-) */
     fcpl2 = H5Pcopy(fcpl);
     CHECK(fcpl2, FAIL, "H5Pcopy");
-
-    /* Make attributes > 1 byte shared (i.e. all of them :-) */
     ret = H5Pset_shared_mesg_nindexes(fcpl2, (unsigned)1);
     CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
     ret = H5Pset_shared_mesg_index(fcpl2, (unsigned)0, H5O_SHMESG_ATTR_FLAG, (unsigned)1);
     CHECK_I(ret, "H5Pset_shared_mesg_index");
 
-    /* Loop over using new group format */
-    for(new_format = FALSE; new_format <= TRUE; new_format++) {
-        hid_t my_fapl;
+    for(minimize_dset_oh = 0; minimize_dset_oh <= 1; minimize_dset_oh++) {
+        if(minimize_dset_oh == 0) {
+            MESSAGE(7, ("testing with default dataset object headers\n"));
+            dcpl_g = H5P_DEFAULT;
+        } else {
+            MESSAGE(7, ("testing with minimzied dataset object headers\n"));
+            dcpl = H5Pcreate(H5P_DATASET_CREATE);
+            CHECK(dcpl, FAIL, "H5Pcreate");
+            ret = H5Pset_dset_no_attrs_hint(dcpl, TRUE);
+            CHECK_I(ret, "H5Pset_dset_no_attrs_hint");
+            dcpl_g = dcpl;
+        }
+
+        for(new_format = FALSE; new_format <= TRUE; new_format++) {
+            hid_t my_fapl;
 
-        /* Set the FAPL for the type of format */
-        if(new_format) {
-            MESSAGE(7, ("testing with new file format\n"));
-            my_fapl = fapl2;
-        } /* end if */
-        else {
-            MESSAGE(7, ("testing with old file format\n"));
-            my_fapl = fapl;
-        } /* end else */
+            if(new_format) {
+                MESSAGE(7, ("testing with new file format\n"));
+                my_fapl = fapl2;
+            } else {
+                MESSAGE(7, ("testing with old file format\n"));
+                my_fapl = fapl;
+            }
 
-        /* These next two tests use the same file information */
-        test_attr_basic_write(my_fapl);    /* Test basic H5A writing code */
-        test_attr_basic_read(my_fapl);     /* Test basic H5A reading code */
+            /* These next two tests use the same file information */
+            test_attr_basic_write(my_fapl);    /* Test basic H5A writing code */
+            test_attr_basic_read(my_fapl);     /* Test basic H5A reading code */
 
-        /* These next two tests use their own file information */
-        test_attr_flush(my_fapl);          /* Test H5A I/O in the presence of H5Fflush calls */
-        test_attr_plist(my_fapl);          /* Test attribute property lists */
+            /* These next two tests use their own file information */
+            test_attr_flush(my_fapl);          /* Test H5A I/O in the presence of H5Fflush calls */
+            test_attr_plist(my_fapl);          /* Test attribute property lists */
 
-        /* These next two tests use the same file information */
-        test_attr_compound_write(my_fapl);  /* Test complex datatype H5A writing code */
-        test_attr_compound_read(my_fapl);   /* Test complex datatype H5A reading code */
+            /* These next two tests use the same file information */
+            test_attr_compound_write(my_fapl);  /* Test complex datatype H5A writing code */
+            test_attr_compound_read(my_fapl);   /* Test complex datatype H5A reading code */
 
-        /* These next two tests use the same file information */
-        test_attr_scalar_write(my_fapl);  /* Test scalar dataspace H5A writing code */
-        test_attr_scalar_read(my_fapl);   /* Test scalar dataspace H5A reading code */
+            /* These next two tests use the same file information */
+            test_attr_scalar_write(my_fapl);  /* Test scalar dataspace H5A writing code */
+            test_attr_scalar_read(my_fapl);   /* Test scalar dataspace H5A reading code */
 
-        /* These next four tests use the same file information */
-        test_attr_mult_write(my_fapl);     /* Test H5A writing code for multiple attributes */
-        test_attr_mult_read(my_fapl);      /* Test H5A reading code for multiple attributes */
-        test_attr_iterate(my_fapl);        /* Test H5A iterator code */
-        test_attr_delete(my_fapl);         /* Test H5A code for deleting attributes */
+            /* These next four tests use the same file information */
+            test_attr_mult_write(my_fapl);     /* Test H5A writing code for multiple attributes */
+            test_attr_mult_read(my_fapl);      /* Test H5A reading code for multiple attributes */
+            test_attr_iterate(my_fapl);        /* Test H5A iterator code */
+            test_attr_delete(my_fapl);         /* Test H5A code for deleting attributes */
 
-        /* This next test uses its own file information */
-        test_attr_dtype_shared(my_fapl);   /* Test using shared dataypes in attributes */
+            /* This next test uses its own file information */
+            test_attr_dtype_shared(my_fapl);   /* Test using shared dataypes in attributes */
 
-        /* This next test uses its own file information */
-        test_attr_duplicate_ids(my_fapl);
+            /* This next test uses its own file information */
+            test_attr_duplicate_ids(my_fapl);
 
-        /* Tests on "new format" attribute storage */
-        if(new_format == TRUE) {
-            /* Loop over using shared attributes */
             for(use_shared = FALSE; use_shared <= TRUE; use_shared++) {
                 hid_t my_fcpl;
 
-                /* Set the FCPL for shared or not */
-                if(use_shared) {
+                if(new_format == TRUE && use_shared) {
                     MESSAGE(7, ("testing with shared attributes\n"));
                     my_fcpl = fcpl2;
-                } /* end if */
-                else {
+                } else {
                     MESSAGE(7, ("testing without shared attributes\n"));
                     my_fcpl = fcpl;
-                } /* end else */
-
-                /* General attribute tests */
-                test_attr_dense_create(my_fcpl, my_fapl);       /* Test dense attribute storage creation */
-                test_attr_dense_open(my_fcpl, my_fapl);         /* Test opening attributes in dense storage */
-                test_attr_dense_delete(my_fcpl, my_fapl);       /* Test deleting attributes in dense storage */
-                test_attr_dense_rename(my_fcpl, my_fapl);       /* Test renaming attributes in dense storage */
-                test_attr_dense_unlink(my_fcpl, my_fapl);       /* Test unlinking object with attributes in dense storage */
-                test_attr_dense_limits(my_fcpl, my_fapl);       /* Test dense attribute storage limits */
-                test_attr_dense_dup_ids(my_fcpl, my_fapl);      /* Test duplicated IDs for dense attribute storage */
+                }
 
                 test_attr_big(my_fcpl, my_fapl);                /* Test storing big attribute */
                 test_attr_null_space(my_fcpl, my_fapl);         /* Test storing attribute with NULL dataspace */
@@ -11034,15 +11177,8 @@ test_attr(void)
                 test_attr_info_null_info_pointer(my_fcpl, my_fapl); /* Test passing a NULL attribute info pointer to H5Aget_info(_by_name/_by_idx) */
                 test_attr_rename_invalid_name(my_fcpl, my_fapl); /* Test passing a NULL or empty attribute name to H5Arename(_by_name) */
 
-                /* Attribute creation order tests */
-                test_attr_corder_create_basic(my_fcpl, my_fapl);/* Test creating an object w/attribute creation order info */
-                test_attr_corder_create_compact(my_fcpl, my_fapl);  /* Test compact attribute storage on an object w/attribute creation order info */
-                test_attr_corder_create_dense(my_fcpl, my_fapl);/* Test dense attribute storage on an object w/attribute creation order info */
-                test_attr_corder_create_reopen(my_fcpl, my_fapl);/* Test creating attributes w/reopening file from using new format to using old format */
-                test_attr_corder_transition(my_fcpl, my_fapl);  /* Test attribute storage transitions on an object w/attribute creation order info */
-                test_attr_corder_delete(my_fcpl, my_fapl);      /* Test deleting object using dense storage w/attribute creation order info */
-
-                /* New attribute API routine tests */
+                /* New attribute API routine tests
+                 */
                 test_attr_info_by_idx(new_format, my_fcpl, my_fapl);    /* Test querying attribute info by index */
                 test_attr_delete_by_idx(new_format, my_fcpl, my_fapl);  /* Test deleting attribute by index */
                 test_attr_iterate2(new_format, my_fcpl, my_fapl);       /* Test iterating over attributes by index */
@@ -11050,58 +11186,68 @@ test_attr(void)
                 test_attr_open_by_name(new_format, my_fcpl, my_fapl);   /* Test opening attributes by name */
                 test_attr_create_by_name(new_format, my_fcpl, my_fapl); /* Test creating attributes by name */
 
-                /* More complex tests with both "new format" and "shared" attributes */
-                if(use_shared == TRUE) {
-                    test_attr_shared_write(my_fcpl, my_fapl);   /* Test writing to shared attributes in compact & dense storage */
-                    test_attr_shared_rename(my_fcpl, my_fapl);  /* Test renaming shared attributes in compact & dense storage */
-                    test_attr_shared_delete(my_fcpl, my_fapl);  /* Test deleting shared attributes in compact & dense storage */
-                    test_attr_shared_unlink(my_fcpl, my_fapl);  /* Test unlinking object with shared attributes in compact & dense storage */
-                } /* end if */
-
-                /* Tests that address specific bugs */
+                /* Tests that address specific bugs
+                 */
                 test_attr_bug1(my_fcpl, my_fapl);               /* Test odd allocation operations */
                 test_attr_bug2(my_fcpl, my_fapl);               /* Test many deleted attributes */
                 test_attr_bug3(my_fcpl, my_fapl);               /* Test "self referential" attributes */
                 test_attr_bug4(my_fcpl, my_fapl);               /* Test attributes on named datatypes */
                 test_attr_bug5(my_fcpl, my_fapl);               /* Test opening/closing attributes through different file handles */
                 test_attr_bug6(my_fcpl, my_fapl);               /* Test reading empty attribute */
-                test_attr_bug7(my_fcpl, my_fapl);               /* Test creating and deleting large attributes in ohdr chunk 0 */
+                /* test_attr_bug7 is specific to the "new" object header format,
+                 * and in fact fails if used with the old format due to the
+                 * attributes being larger than 64K */
                 test_attr_bug8(my_fcpl, my_fapl);               /* Test attribute expanding object header with undecoded messages */
                 test_attr_bug9(my_fcpl, my_fapl);               /* Test large attributes converting to dense storage */
-                test_attr_delete_last_dense(my_fcpl, my_fapl);  /* Test */
-            } /* end for */
-        } /* end if */
-        else {
-            /* General attribute tests */
-            test_attr_big(fcpl, my_fapl);                       /* Test storing big attribute */
-            test_attr_null_space(fcpl, my_fapl);                /* Test storing attribute with NULL dataspace */
-            test_attr_deprec(fcpl, my_fapl);                    /* Test deprecated API routines */
-            test_attr_many(new_format, fcpl, my_fapl);               /* Test storing lots of attributes */
-            test_attr_info_null_info_pointer(fcpl, my_fapl); /* Test passing a NULL attribute info pointer to H5Aget_info(_by_name/_by_idx) */
-            test_attr_rename_invalid_name(fcpl, my_fapl); /* Test passing a NULL or empty attribute name to H5Arename(_by_name) */
-
-            /* New attribute API routine tests, on old-format storage */
-            test_attr_info_by_idx(new_format, fcpl, my_fapl);   /* Test querying attribute info by index */
-            test_attr_delete_by_idx(new_format, fcpl, my_fapl); /* Test deleting attribute by index */
-            test_attr_iterate2(new_format, fcpl, my_fapl);      /* Test iterating over attributes by index */
-            test_attr_open_by_idx(new_format, fcpl, my_fapl);   /* Test opening attributes by index */
-            test_attr_open_by_name(new_format, fcpl, my_fapl);  /* Test opening attributes by name */
-            test_attr_create_by_name(new_format, fcpl, my_fapl); /* Test creating attributes by name */
-
-            /* Tests that address specific bugs */
-            test_attr_bug1(fcpl, my_fapl);                      /* Test odd allocation operations */
-            test_attr_bug2(fcpl, my_fapl);                      /* Test many deleted attributes */
-            test_attr_bug3(fcpl, my_fapl);                      /* Test "self referential" attributes */
-            test_attr_bug4(fcpl, my_fapl);                      /* Test attributes on named datatypes */
-            test_attr_bug5(fcpl, my_fapl);                      /* Test opening/closing attributes through different file handles */
-            test_attr_bug6(fcpl, my_fapl);                      /* Test reading empty attribute */
-            /* Skip test_attr_bug7 because it is specific to the new object
-             * header format and in fact fails if used with the old format, due
-             * to the attributes being larger than 64K */
-            test_attr_bug8(fcpl, my_fapl);                      /* Test attribute expanding object header with undecoded messages */
-            test_attr_bug9(fcpl, my_fapl);                      /* Test large attributes converting to dense storage */
-        } /* end else */
-    } /* end for */
+
+                /* tests specific to the "new format"
+                 */
+                if (new_format == TRUE) {
+                    /* General attribute tests */
+                    test_attr_dense_create(my_fcpl, my_fapl);       /* Test dense attribute storage creation */
+                    test_attr_dense_open(my_fcpl, my_fapl);         /* Test opening attributes in dense storage */
+                    test_attr_dense_delete(my_fcpl, my_fapl);       /* Test deleting attributes in dense storage */
+                    test_attr_dense_rename(my_fcpl, my_fapl);       /* Test renaming attributes in dense storage */
+                    test_attr_dense_unlink(my_fcpl, my_fapl);       /* Test unlinking object with attributes in dense storage */
+                    test_attr_dense_limits(my_fcpl, my_fapl);       /* Test dense attribute storage limits */
+                    test_attr_dense_dup_ids(my_fcpl, my_fapl);      /* Test duplicated IDs for dense attribute storage */
+
+                    /* Attribute creation order tests
+                     */
+                    test_attr_corder_create_basic(my_fcpl, my_fapl);/* Test creating an object w/attribute creation order info */
+                    test_attr_corder_create_compact(my_fcpl, my_fapl);  /* Test compact attribute storage on an object w/attribute creation order info */
+                    test_attr_corder_create_dense(my_fcpl, my_fapl);/* Test dense attribute storage on an object w/attribute creation order info */
+                    test_attr_corder_create_reopen(my_fcpl, my_fapl);/* Test creating attributes w/reopening file from using new format to using old format */
+                    test_attr_corder_transition(my_fcpl, my_fapl);  /* Test attribute storage transitions on an object w/attribute creation order info */
+                    test_attr_corder_delete(my_fcpl, my_fapl);      /* Test deleting object using dense storage w/attribute creation order info */
+
+                    /* More complex tests with exclusively both "new format" and "shared" attributes
+                     */
+                    if(use_shared == TRUE) {
+                        test_attr_shared_write(my_fcpl, my_fapl);   /* Test writing to shared attributes in compact & dense storage */
+                        test_attr_shared_rename(my_fcpl, my_fapl);  /* Test renaming shared attributes in compact & dense storage */
+                        test_attr_shared_delete(my_fcpl, my_fapl);  /* Test deleting shared attributes in compact & dense storage */
+                        test_attr_shared_unlink(my_fcpl, my_fapl);  /* Test unlinking object with shared attributes in compact & dense storage */
+                    } /* if using shared attributes */
+
+                    test_attr_delete_last_dense(my_fcpl, my_fapl);
+
+                    /* test_attr_bug7 is specific to the "new" object header format,
+                     * and in fact fails if used with the old format due to the
+                     * attributes being larger than 64K */
+                    test_attr_bug7(my_fcpl, my_fapl);               /* Test creating and deleting large attributes in ohdr chunk 0 */
+
+                } /* if using "new format" */
+            } /* for unshared/shared attributes */
+        } /* for old/new format */
+
+        if (minimize_dset_oh != 0) {
+            ret = H5Pclose(dcpl);
+            CHECK(ret, FAIL, "H5Pclose");
+            dcpl_g = H5P_DEFAULT;
+        }
+
+    } /* for default/minimized dataset object headers */
 
     /* Close  FCPLs */
     ret = H5Pclose(fcpl);
diff --git a/test/test_vol_plugin.sh.in b/test/test_vol_plugin.sh.in
new file mode 100644
index 0000000..38220ef
--- /dev/null
+++ b/test/test_vol_plugin.sh.in
@@ -0,0 +1,84 @@
+#! /bin/sh
+#
+# Copyright by The HDF Group.                                              
+# All rights reserved.                                                     
+#                                                                          
+# This file is part of HDF5. The full HDF5 copyright notice, including     
+# terms governing use, modification, and redistribution, is contained in   
+# the COPYING file, which can be found at the root of the source code
+# distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.
+# If you do not have access to either file, you may request a copy from
+# help@hdfgroup.org.
+#
+# This shell script is for testing VOL connector plugins.
+#
+srcdir=@srcdir@
+TOP_BUILDDIR=@top_builddir@
+
+EXIT_SUCCESS=0
+EXIT_FAILURE=1
+
+nerrors=0
+verbose=yes
+exit_code=$EXIT_SUCCESS
+
+TEST_NAME=vol_plugin
+TEST_BIN=`pwd`/$TEST_NAME
+FROM_DIR=`pwd`/.libs
+case $(uname) in
+    CYGWIN* )
+        NULL_VOL_PLUGIN="$FROM_DIR/cygnull_vol_connector*"
+        ;;
+    *)
+        NULL_VOL_PLUGIN="$FROM_DIR/libnull_vol_connector*"
+        ;;
+esac
+TEMP_PLUGIN_DIR=null_vol_plugin_dir
+CP="cp -p"    # Use -p to preserve mode,ownership, timestamps
+RM="rm -rf"
+
+# Print a line-line message left justified in a field of 70 characters
+# beginning with the word "Testing".
+#
+TESTING() {
+    SPACES="                                                               "
+    echo "Testing $* $SPACES" | cut -c1-70 | tr -d '\012'
+}
+
+# Main Body
+# Create test directory if necessary.
+test -d $TEMP_PLUGIN_DIR || mkdir -p $TEMP_PLUGIN_DIR
+if [ $? != 0 ]; then
+    echo "Failed to create VOL connector plugin test directory ($TEMP_PLUGIN_DIR)"
+    exit $EXIT_FAILURE
+fi
+
+# Copy plugin for the tests.
+$CP $NULL_VOL_PLUGIN $TEMP_PLUGIN_DIR
+if [ $? != 0 ]; then
+    echo "Failed to copy NULL VOL plugin ($NULL_VOL_PLUGIN) to test directory."
+    exit $EXIT_FAILURE
+fi
+
+# setup plugin path
+ENVCMD="env HDF5_PLUGIN_PATH=${TEMP_PLUGIN_DIR}"
+
+# Run the test
+$ENVCMD $TEST_BIN
+if [ $? != 0 ]; then
+    nerrors=`expr $nerrors + 1`
+fi
+
+# print results
+if test $nerrors -ne 0 ; then
+    echo "$nerrors errors encountered"
+    exit_code=$EXIT_FAILURE
+else
+    echo "All VOL plugin tests passed."
+    exit_code=$EXIT_SUCCESS
+fi
+
+# Clean up temporary files/directories and leave
+$RM $TEMP_PLUGIN_DIR
+
+exit $exit_code
diff --git a/test/tfile.c b/test/tfile.c
index 8a8b889..5338c32 100644
--- a/test/tfile.c
+++ b/test/tfile.c
@@ -7141,6 +7141,132 @@ test_incr_filesize(void)
 
 /****************************************************************
 **
+**  test_min_dset_ohdr():
+**    Test API calls to toggle dataset object header minimization.
+**
+**  TODO (as separate function?):
+**    + setting persists between close and (re)open?
+**    + dataset header sizes created while changing value of toggle
+**
+****************************************************************/
+static void
+test_min_dset_ohdr(void)
+{
+    const char basename[]       = "min_dset_ohdr_testfile";
+    char filename[FILENAME_LEN] = "";
+    hid_t      file_id          = -1;
+    hid_t      file2_id         = -1;
+    hbool_t    minimize;
+    herr_t     ret;
+
+    MESSAGE(5, ("Testing dataset object header minimization\n"));
+
+    /*********/
+    /* SETUP */
+    /*********/
+
+    h5_fixname(basename, H5P_DEFAULT, filename, sizeof(filename));
+
+    file_id = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK_I(file_id, "H5Fcreate");
+
+    /*********/
+    /* TESTS */
+    /*********/
+
+    /*----------------------------------------
+     * TEST default value
+     */
+    ret = H5Fget_dset_no_attrs_hint(file_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, FALSE, "minimize flag");
+
+    /*----------------------------------------
+     * TEST set to TRUE
+     */
+    ret = H5Fset_dset_no_attrs_hint(file_id, TRUE);
+    CHECK(ret, FAIL, "H5Fset_dset_no_attrs_hint");
+
+    ret = H5Fget_dset_no_attrs_hint(file_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, TRUE, "minimize flag");
+
+    /*----------------------------------------
+     * TEST second file open on same filename
+     */
+    file2_id = H5Fopen(filename, H5F_ACC_RDWR, H5P_DEFAULT);
+    CHECK_I(file2_id, "H5Fopen");
+
+    /* verify TRUE setting on second open
+     */
+    ret = H5Fget_dset_no_attrs_hint(file_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, TRUE, "minimize flag");
+
+    /* re-set to FALSE on first open
+     */
+    ret = H5Fset_dset_no_attrs_hint(file_id, FALSE);
+    CHECK(ret, FAIL, "H5Fset_dset_no_attrs_hint");
+
+    /* verify FALSE set on both opens
+     */
+    ret = H5Fget_dset_no_attrs_hint(file_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, FALSE, "minimize flag");
+
+    ret = H5Fget_dset_no_attrs_hint(file2_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, FALSE, "minimize flag");
+
+    /* re-set to TRUE on second open
+     */
+    ret = H5Fset_dset_no_attrs_hint(file2_id, TRUE);
+    CHECK(ret, FAIL, "H5Fset_dset_no_attrs_hint");
+
+    /* verify TRUE set on both opens
+     */
+    ret = H5Fget_dset_no_attrs_hint(file_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, TRUE, "minimize flag");
+
+    ret = H5Fget_dset_no_attrs_hint(file2_id, &minimize);
+    CHECK(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+    VERIFY(minimize, TRUE, "minimize flag");
+
+    /*----------------------------------------
+     * TEST error cases
+     */
+
+    /* trying to set with invalid file ID */
+    H5E_BEGIN_TRY {
+        ret = H5Fset_dset_no_attrs_hint(-1, TRUE);
+    } H5E_END_TRY;
+    VERIFY(ret, FAIL, "H5Fset_dset_no_attrs_hint");
+
+    /* trying to get with invalid file ID */
+    H5E_BEGIN_TRY {
+        ret = H5Fget_dset_no_attrs_hint(-1, &minimize);
+    } H5E_END_TRY;
+    VERIFY(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+
+    /* trying to get with invalid pointer */
+    H5E_BEGIN_TRY {
+        ret = H5Fget_dset_no_attrs_hint(file_id, NULL);
+    } H5E_END_TRY;
+    VERIFY(ret, FAIL, "H5Fget_dset_no_attrs_hint");
+
+    /************/
+    /* TEARDOWN */
+    /************/
+
+    ret = H5Fclose(file_id);
+    CHECK(ret, FAIL, "H5Fclose");
+    ret = H5Fclose(file2_id);
+    CHECK(ret, FAIL, "H5Fclose");
+} /* end test_min_dset_ohdr() */
+
+/****************************************************************
+**
 **  test_deprec():
 **    Test deprecated functionality.
 **
@@ -7426,6 +7552,7 @@ test_file(void)
     test_libver_macros();                       /* Test the macros for library version comparison */
     test_libver_macros2();                      /* Test the macros for library version comparison */
     test_incr_filesize();                       /* Test H5Fincrement_filesize() and H5Fget_eoa() */
+    test_min_dset_ohdr();                       /* Test datset object header minimization */
 #ifndef H5_NO_DEPRECATED_SYMBOLS
     test_file_ishdf5();                         /* Test detecting HDF5 files correctly */
     test_deprec();                              /* Test deprecated routines */
diff --git a/test/tsohm.c b/test/tsohm.c
index 718b12f..bd73d00 100644
--- a/test/tsohm.c
+++ b/test/tsohm.c
@@ -13,7 +13,7 @@
 
 /***********************************************************
 *
-* Test program:	 tsohm
+* Test program: tsohm
 *
 * Test Shared Object Header Messages
 *
@@ -25,9 +25,9 @@
  * This file needs to access private information from the H5F package.
  * This file also needs to access the file testing code.
  */
-#define H5F_FRIEND		/*suppress error about including H5Fpkg	  */
+#define H5F_FRIEND   /* suppress error about including H5Fpkg      */
 #define H5F_TESTING
-#include "H5Fpkg.h"		/* File access	 			*/
+#include "H5Fpkg.h"  /* File access */
 
 /* Default SOHM values */
 #define DEF_NUM_INDEXES 0
@@ -178,40 +178,39 @@ static void test_sohm_extlink(void);
 
 /****************************************************************
 **
-**  check_fcpl_values(): Helper function for test_sohm_fcpl.
-**         Verifies that the *_in and *_out parameters are equal.
+**  verify_fcpl_values(): Verifies that FCPL is set as expected.
 **
 ****************************************************************/
-static void check_fcpl_values(hid_t fcpl_id, const unsigned nindexes_in,
-                const unsigned *flags_in, const unsigned *minsizes_in,
-                unsigned l2b, unsigned b2l)
+static void
+verify_fcpl_values(hid_t fcpl_id, const unsigned nindexes_expected, const unsigned *flags_expected, const unsigned *minsizes_expected, unsigned l2b, unsigned b2l)
 {
-    unsigned    num_indexes;
-    unsigned    index_flags, min_mesg_size;
-    unsigned    list_size, btree_size;
-    unsigned     x;
-    herr_t      ret;
-
-    /* Verify number of indexes is set to default */
-    ret = H5Pget_shared_mesg_nindexes(fcpl_id, &num_indexes);
+    unsigned  nindexes_actual;
+    unsigned  list_size;
+    unsigned  btree_size;
+    unsigned  x;
+    herr_t    ret;
+
+    /* Number of indexes */
+    ret = H5Pget_shared_mesg_nindexes(fcpl_id, &nindexes_actual);
     CHECK_I(ret, "H5Pget_shared_mesg_nindexes");
-    VERIFY(num_indexes, nindexes_in, "H5Pget_shared_mesg_nindexes");
+    VERIFY(nindexes_actual, nindexes_expected, "H5Pget_shared_mesg_nindexes");
 
-    /* Verify index flags and minsizes are set */
-    for(x=0; x<num_indexes; ++x)
-    {
-        ret = H5Pget_shared_mesg_index(fcpl_id, x, &index_flags, &min_mesg_size);
+    /* Index flags and minsizes */
+    for(x=0; x<nindexes_actual; ++x) {
+        unsigned flags_i;
+        unsigned min_mesg_size;
+        ret = H5Pget_shared_mesg_index(fcpl_id, x, &flags_i, &min_mesg_size);
         CHECK_I(ret, "H5Pget_shared_mesg_index");
-        VERIFY(index_flags, flags_in[x], "H5Pget_shared_mesg_index");
-        VERIFY(min_mesg_size, minsizes_in[x], "H5Pget_shared_mesg_index");
+        VERIFY(flags_i, flags_expected[x], "H5Pget_shared_mesg_index");
+        VERIFY(min_mesg_size, minsizes_expected[x], "H5Pget_shared_mesg_index");
     }
 
-    /* Check list-to-btree and btree-to-list values */
+    /* List-to-btree and btree-to-list values */
     ret = H5Pget_shared_mesg_phase_change(fcpl_id, &list_size, &btree_size);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
     VERIFY(list_size, l2b, "H5Pset_shared_mesg_phase_change");
     VERIFY(btree_size, b2l, "H5Pset_shared_mesg_phase_change");
-}
+} /* verify_fcpl_values */
 
 
 /****************************************************************
@@ -219,22 +218,21 @@ static void check_fcpl_values(hid_t fcpl_id, const unsigned nindexes_in,
 **  test_sohm_fcpl(): Test File Creation Property Lists.
 **
 ****************************************************************/
-static void test_sohm_fcpl(void)
+static void
+test_sohm_fcpl(void)
 {
-    hid_t       fid = -1;
-    hid_t       fcpl_id = -1;
-    hid_t       fcpl2_id = -1;
-    unsigned    x;
-    herr_t	ret;		/* Generic return value	*/
+    hid_t    fid = -1;
+    hid_t    fcpl_id = -1;
+    hid_t    fcpl2_id = -1;
+    unsigned x;
+    herr_t   ret;
 
-    /* Output message about test being performed */
     MESSAGE(5, ("Testing File Creation Properties for Shared Messages\n"));
 
     fcpl_id = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl_id, "H5Pcreate");
 
-    /* Verify fcpl values */
-    check_fcpl_values(fcpl_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
+    verify_fcpl_values(fcpl_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
 
     /* Create a file with this fcpl and make sure that all the values can be
      * retrieved.
@@ -245,8 +243,7 @@ static void test_sohm_fcpl(void)
     fcpl2_id = H5Fget_create_plist(fid);
     CHECK_I(fcpl2_id, "H5Fcreate");
 
-    /* Verify fcpl values */
-    check_fcpl_values(fcpl2_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
+    verify_fcpl_values(fcpl2_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
 
     ret = H5Pclose(fcpl2_id);
     CHECK_I(ret, "H5Pclose");
@@ -262,8 +259,7 @@ static void test_sohm_fcpl(void)
     fcpl2_id = H5Fget_create_plist(fid);
     CHECK_I(ret, "H5Fcreate");
 
-    /* Verify fcpl values */
-    check_fcpl_values(fcpl2_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
+    verify_fcpl_values(fcpl2_id, DEF_NUM_INDEXES, def_type_flags, def_minsizes, DEF_L2B, DEF_B2L);
 
     /* Clean up */
     ret = H5Pclose(fcpl2_id);
@@ -289,7 +285,7 @@ static void test_sohm_fcpl(void)
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, TEST_L2B, TEST_B2L);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    check_fcpl_values(fcpl_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
+    verify_fcpl_values(fcpl_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
 
     /* Use the fcpl to create a file and get it back again */
     fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
@@ -297,8 +293,7 @@ static void test_sohm_fcpl(void)
     fcpl2_id = H5Fget_create_plist(fid);
     CHECK_I(fcpl2_id, "H5Fcreate");
 
-    /* Verify fcpl values */
-    check_fcpl_values(fcpl2_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
+    verify_fcpl_values(fcpl2_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
 
     ret = H5Pclose(fcpl2_id);
     CHECK_I(ret, "H5Pclose");
@@ -314,8 +309,7 @@ static void test_sohm_fcpl(void)
     fcpl2_id = H5Fget_create_plist(fid);
     CHECK_I(ret, "H5Fcreate");
 
-    /* Verify fcpl values */
-    check_fcpl_values(fcpl2_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
+    verify_fcpl_values(fcpl2_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
 
     /* Clean up */
     ret = H5Pclose(fcpl2_id);
@@ -323,7 +317,70 @@ static void test_sohm_fcpl(void)
     ret = H5Fclose(fid);
     CHECK_I(ret, "H5Fclose");
 
-    /* Test giving bogus values to H5P* functions */
+    /* Actually, the list max can be exactly 1 greater than the
+     * btree min, but no more.
+     * Reset the second index.
+     */
+    ret = H5Pset_shared_mesg_index(fcpl_id, 1, test_type_flags[1], 15);
+    CHECK_I(ret, "H5Pset_shared_mesg_index");
+    ret = H5Pset_shared_mesg_phase_change(fcpl_id, 10, 11);
+    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+    fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
+    CHECK_I(fid, "H5Fcreate");
+    ret = H5Fclose(fid);
+    CHECK_I(ret, "H5Fclose");
+
+    /* Test edge cases:
+     * H5O_SHMESG_MAX_NINDEXES and H5O_SHMESG_MAX_LIST_SIZE should be valid
+     * values.
+     * Creating a file with uninitialized indexes should work. (TODO: not implemented?)
+     */
+    ret = H5Pset_shared_mesg_nindexes(fcpl_id, H5O_SHMESG_MAX_NINDEXES);
+    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+    ret = H5Pset_shared_mesg_phase_change(fcpl_id, H5O_SHMESG_MAX_LIST_SIZE, H5O_SHMESG_MAX_LIST_SIZE);
+    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+    fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
+    CHECK_I(fid, "H5Fcreate");
+
+    /* Clean up */
+    ret = H5Pclose(fcpl_id);
+    CHECK_I(ret, "H5Pclose");
+    ret = H5Fclose(fid);
+    CHECK_I(ret, "H5Fclose");
+} /* test_sohm_fcpl */
+
+
+/****************************************************************
+**
+**  test_sohm_fcpl_errors(): Test bogus FCPL settings for SOHMs
+**
+****************************************************************/
+static void
+test_sohm_fcpl_errors(void)
+{
+    hid_t    fcpl_id = -1;
+    hid_t    fid     = -1;
+    unsigned x;
+    herr_t   ret;
+
+    MESSAGE(5, ("Testing bogus file creation properties for shared messages\n"));
+
+    fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+    CHECK_I(fcpl_id, "H5Pcreate");
+
+    /* Set up index values */
+    ret = H5Pset_shared_mesg_nindexes(fcpl_id, TEST_NUM_INDEXES);
+    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+    for(x = 0; x < TEST_NUM_INDEXES; ++x) {
+        ret = H5Pset_shared_mesg_index(fcpl_id, x, test_type_flags[x], test_minsizes[x]);
+        CHECK_I(ret, "H5Pset_shared_mesg_index");
+    }
+
+    ret = H5Pset_shared_mesg_phase_change(fcpl_id, TEST_L2B, TEST_B2L);
+    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+
+    verify_fcpl_values(fcpl_id, TEST_NUM_INDEXES, test_type_flags, test_minsizes, TEST_L2B, TEST_B2L);
+
     H5E_BEGIN_TRY {
         /* Trying to create too many indexes should fail */
         ret = H5Pset_shared_mesg_nindexes(fcpl_id, H5O_SHMESG_MAX_NINDEXES + 1);
@@ -370,40 +427,7 @@ static void test_sohm_fcpl(void)
         ret = H5Pset_shared_mesg_phase_change(fcpl_id, H5O_SHMESG_MAX_LIST_SIZE, H5O_SHMESG_MAX_LIST_SIZE+1);
         VERIFY(ret, -1, "H5Pset_shared_mesg_phase_change");
     } H5E_END_TRY
-
-
-    /* Actually, the list max can be exactly 1 greater than the
-     * btree min, but no more.  Also, the errors above shouldn't
-     * have corrupted the fcpl, although we do need to reset the
-     * second index that we changed above.
-     */
-    ret = H5Pset_shared_mesg_index(fcpl_id, 1, test_type_flags[1], 15);
-    CHECK_I(ret, "H5Pset_shared_mesg_index");
-    ret = H5Pset_shared_mesg_phase_change(fcpl_id, 10, 11);
-    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
-    CHECK_I(fid, "H5Fcreate");
-    ret = H5Fclose(fid);
-    CHECK_I(ret, "H5Fclose");
-
-    /* Test edge cases; H5O_SHMESG_MAX_NINDEXES and H5O_SHMESG_MAX_LIST_SIZE should be
-     * valid values.  Also, creating a file with uninitialized indexes
-     * (indexes 3-5) should work.
-     */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, H5O_SHMESG_MAX_NINDEXES);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_phase_change(fcpl_id, H5O_SHMESG_MAX_LIST_SIZE, H5O_SHMESG_MAX_LIST_SIZE);
-    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
-    CHECK_I(fid, "H5Fcreate");
-
-
-    /* Clean up */
-    ret = H5Pclose(fcpl_id);
-    CHECK_I(ret, "H5Pclose");
-    ret = H5Fclose(fid);
-    CHECK_I(ret, "H5Fclose");
-}
+} /* test_sohm_fcpl_errors */
 
 
 /*-------------------------------------------------------------------------
@@ -455,7 +479,8 @@ error:
       H5Tclose(dtype1_id);
     } H5E_END_TRY
     return -1;
-}
+} /* make_dtype1 */
+
 
 /*-------------------------------------------------------------------------
  * Function:    make_dtype_2
@@ -518,9 +543,9 @@ error:
       H5Tclose(int_id);
     } H5E_END_TRY
     return -1;
-}
-
+} /* make_dtype2 */
 
+
 /*-------------------------------------------------------------------------
  * Function:    close_reopen_file
  *
@@ -540,16 +565,16 @@ error:
 static hid_t
 close_reopen_file(hid_t file, const char* filename, hid_t fapl_id)
 {
-    hid_t fid;
-
-    if(H5Fclose(file) < 0) FAIL_STACK_ERROR
-    if((fid = H5Fopen(filename, H5F_ACC_RDWR, fapl_id)) < 0) FAIL_STACK_ERROR
-
-    return(fid);
+    if (H5Fclose(file) < 0)
+        FAIL_STACK_ERROR
+    file = H5Fopen(filename, H5F_ACC_RDWR, fapl_id);
+    if (file < 0)
+        FAIL_STACK_ERROR
+    return(file);
 
 error:
     return -1;
-}
+} /* close_reopen_file */
 
 
 /*-------------------------------------------------------------------------
@@ -557,7 +582,6 @@ error:
  *
  * Purpose:     Creates object headers that use a large datatype message.
  *
- *              Used in test_sohm_basic.  Should close the file ID passed in.
  *              Set test_file_closing to 1 to add file closing and reopening
  *              whenever possible (to test that SOHMs are written correctly
  *              on disk and not just in memory).
@@ -571,7 +595,7 @@ error:
  *-------------------------------------------------------------------------
  */
 static hid_t
-size1_helper(hid_t file, const char* filename, hid_t fapl_id, int test_file_closing)
+size1_helper(hid_t file, const char *filename, hid_t fapl_id, int test_file_closing)
 {
     dtype1_struct wdata;
     dtype1_struct rdata;
@@ -581,6 +605,32 @@ size1_helper(hid_t file, const char* filename, hid_t fapl_id, int test_file_clos
     hsize_t     dim1[1];
     int         x;
 
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ * Macro:      TSOHM_S1H_VERIFY_DATA
+ *
+ * Purpose:    Encapsulate a common pattern:
+ *             Reads the dataset and verifies that [a subset of] the data
+ *             are as expected.
+ *
+ * Programmer: Jacob Smith
+ *             2018 November 1
+ * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ */
+#define TSOHM_S1H_VERIFY_DATA(dset_id, dtype_id) \
+{                                                \
+    HDmemset(&rdata, 0, sizeof(rdata));          \
+    if (0 > H5Dread((dset_id), (dtype_id), H5S_ALL, H5S_ALL, H5P_DEFAULT, &rdata)) { \
+        H5_FAILED(); AT();                       \
+        printf("Can't read data\n");             \
+        goto error;                              \
+    }                                            \
+    if ((rdata.i1 != wdata.i1) || (rdata.i2 != wdata.i2) || HDstrcmp(rdata.str, wdata.str)) { \
+        H5_FAILED(); AT();                       \
+        printf("incorrect read data\n");         \
+        goto error;                              \
+    }                                            \
+} /* TSOHM_S1H_VERIFY_DATA() definition */
+
     /* Closing and re-opening the file takes a long time on systems without
      * local disks.  Don't close and reopen if express testing is enabled.
      */
@@ -603,107 +653,68 @@ size1_helper(hid_t file, const char* filename, hid_t fapl_id, int test_file_clos
     /* Intialize rdata */
     HDmemset(&rdata, 0, sizeof(rdata));
 
-    if((dtype1_id = make_dtype_1()) < 0) TEST_ERROR
+    dtype1_id = make_dtype_1();
+    if(dtype1_id < 0) TEST_ERROR
 
-    /* Create the dataspace and dataset */
     dim1[0] = 1;
-    if((space_id = H5Screate_simple(1, dim1, NULL)) < 0) TEST_ERROR
+    space_id = H5Screate_simple(1, dim1, NULL);
+    if(space_id < 0) TEST_ERROR
 
-    if((dset_id = H5Dcreate2(file, DSETNAME[0], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) FAIL_STACK_ERROR
+    dset_id = H5Dcreate2(file, DSETNAME[0], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    if(dset_id < 0) FAIL_STACK_ERROR
 
     /* Test writing and reading */
     if(H5Dwrite(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &wdata) < 0) FAIL_STACK_ERROR
-
-    if(H5Dread(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &rdata) < 0) FAIL_STACK_ERROR
-
-    if(rdata.i1 != wdata.i1 || rdata.i2 != wdata.i2 || HDstrcmp(rdata.str, wdata.str)) {
-        H5_FAILED(); AT();
-        printf("incorrect read data\n");
-        goto error;
-    } /* end if */
+    TSOHM_S1H_VERIFY_DATA(dset_id, dtype1_id)
     if(H5Dclose(dset_id) < 0) FAIL_STACK_ERROR
 
-    /* Close and re-open the file if requested*/
     if(test_file_closing)
         if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
 
-    /* Create more datasets with the same datatype */
-    if((dset_id = H5Dcreate2(file, DSETNAME[1], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) FAIL_STACK_ERROR
-    if(H5Dclose(dset_id) < 0) FAIL_STACK_ERROR
+    /* Create 3 more datasets with the same datatype/dataspace */
+    for (x = 1; x < 4; x++) {
+        dset_id = H5Dcreate2(file, DSETNAME[x], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+        if (0 > dset_id) FAIL_STACK_ERROR
+        if (x == 3)
+            if(H5Dwrite(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &wdata) < 0) TEST_ERROR
+        if (H5Dclose(dset_id) < 0) FAIL_STACK_ERROR
 
-    /* Close and re-open the file if requested*/
-    if(test_file_closing)
-        if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
-
-    if((dset_id = H5Dcreate2(file, DSETNAME[2], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
-    if(H5Dclose(dset_id) < 0) TEST_ERROR
-
-    /* Close and re-open the file if requested*/
-    if(test_file_closing)
-        if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
-
-    if((dset_id = H5Dcreate2(file,DSETNAME[3],dtype1_id,space_id,H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
-
-    /* Write data to dataset 3 for later */
-    if(H5Dwrite(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &wdata) < 0) TEST_ERROR
+        if (test_file_closing)
+            if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
+    }
 
-    if(H5Dclose(dset_id) < 0) TEST_ERROR
     if(H5Tclose(dtype1_id) < 0) TEST_ERROR
 
-    /* Close and re-open the file if requested*/
-    if(test_file_closing)
-        if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
-
     /* Make sure the data has been written successfully */
-    if((dset_id = H5Dopen2(file, DSETNAME[0], H5P_DEFAULT)) < 0) TEST_ERROR
-    if((dtype1_id = H5Dget_type(dset_id)) < 0) TEST_ERROR
-
-    /* Read data back again */
-    HDmemset(&rdata, 0, sizeof(rdata));
-    if(H5Dread(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &rdata) < 0) {
-        H5_FAILED(); AT();
-        printf("Can't read data\n");
-        goto error;
-    } /* end if */
-
-    if(rdata.i1 != wdata.i1 || rdata.i2 != wdata.i2 || HDstrcmp(rdata.str, wdata.str)) {
-        H5_FAILED(); AT();
-        printf("incorrect read data\n");
-        goto error;
-    } /* end if */
+    dset_id = H5Dopen2(file, DSETNAME[0], H5P_DEFAULT);
+    if(dset_id < 0) TEST_ERROR
+    dtype1_id = H5Dget_type(dset_id);
+    if(dtype1_id < 0) TEST_ERROR
+    TSOHM_S1H_VERIFY_DATA(dset_id, dtype1_id)
 
     if(H5Dclose(dset_id) < 0) TEST_ERROR
 
-    /* Create several copies of the dataset (this increases the amount of space saved by sharing the datatype message) */
+    /* Create several copies of the dataset
+     * this increases the amount of space saved by sharing the datatype message
+     */
     for(x = 0; x < SOHM_HELPER_NUM_EX_DSETS; x++) {
-        if((dset_id = H5Dcreate2(file, EXTRA_DSETNAME[x], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) TEST_ERROR
+        dset_id = H5Dcreate2(file, EXTRA_DSETNAME[x], dtype1_id, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+        if(dset_id < 0) TEST_ERROR
         if(H5Dclose(dset_id) < 0) TEST_ERROR
 
-        /* Close and re-open the file if requested*/
         if(test_file_closing)
             if((file = close_reopen_file(file, filename, fapl_id)) < 0) TEST_ERROR
-    } /* end for */
+    }
 
     if(H5Tclose(dtype1_id) < 0) TEST_ERROR
     if(H5Sclose(space_id) < 0) TEST_ERROR
 
     /* Ensure that we can still read data back from dataset 3 */
-    if((dset_id = H5Dopen2(file, DSETNAME[3], H5P_DEFAULT)) < 0) TEST_ERROR
-    if((dtype1_id = H5Dget_type(dset_id)) < 0) TEST_ERROR
-
-    /* Read data back again */
-    HDmemset(&rdata, 0, sizeof(rdata));
-    if(H5Dread(dset_id, dtype1_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, &rdata) < 0) {
-        H5_FAILED(); AT();
-        printf("Can't read data\n");
-        goto error;
-    } /* end if */
-
-    if(rdata.i1 != wdata.i1 || rdata.i2 != wdata.i2 || HDstrcmp(rdata.str, wdata.str)) {
-        H5_FAILED(); AT();
-        printf("incorrect read data\n");
-        goto error;
-    } /* end if */
+    dset_id = H5Dopen2(file, DSETNAME[3], H5P_DEFAULT);
+    if(dset_id < 0) TEST_ERROR
+    dtype1_id = H5Dget_type(dset_id);
+    if(dtype1_id < 0) TEST_ERROR
+    TSOHM_S1H_VERIFY_DATA(dset_id, dtype1_id)
 
     if(H5Dclose(dset_id) < 0) TEST_ERROR
     if(H5Tclose(dtype1_id) < 0) TEST_ERROR
@@ -717,7 +728,42 @@ size1_helper(hid_t file, const char* filename, hid_t fapl_id, int test_file_clos
         H5Fclose(file);
     } H5E_END_TRY
     return -1;
-}
+#undef TSOHM_S1H_VERIFY_DATA /* macro is exclusive to this function */
+} /* size1_helper */
+
+
+/*----------------------------------------------------------------------------
+ * Function: getsize_testsize1
+ *
+ * Purpose: Creates a test file, populates it, and returns its file size.
+ *          Oject header information from the "first" dataset in the file
+ *          is stored in pointer `oinfo`.
+ *
+ * Programmer: Jacob Smith
+ *             2018 November 1
+ *----------------------------------------------------------------------------
+ */
+static h5_stat_size_t
+getsize_testsize1(const char *filename, hid_t fcpl_id, hid_t fapl_id, unsigned open_close, H5O_info_t *oinfo)
+{
+    hid_t file = -1;
+    herr_t ret;
+
+    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
+    CHECK_I(file, "H5Fcreate");
+
+    file = size1_helper(file, FILENAME, fapl_id, open_close);
+    CHECK_I(file, "size1_helper");
+
+    ret = H5Oget_info_by_name2(file, DSETNAME[0], oinfo, H5O_INFO_HDR, H5P_DEFAULT);
+    CHECK_I(ret, "H5Oget_info_by_name");
+
+    ret = H5Fclose(file);
+    CHECK_I(ret, "H5Fclose");
+
+    return h5_get_file_size(FILENAME, fapl_id);
+} /* getsize_testsize1 */
+
 
 /*-------------------------------------------------------------------------
  * Function:    test_sohm_size1
@@ -727,17 +773,26 @@ size1_helper(hid_t file, const char* filename, hid_t fapl_id, int test_file_clos
  * Programmer:  James Laird
  *              Monday, April 10, 2006
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
-static void test_sohm_size1(void)
+static void
+test_sohm_size1(void)
 {
     hid_t       file = -1;
     hid_t       fcpl_id = -1;
     hid_t       fapl_id = -1;
-    hsize_t     sohm_oh_size;
-    hsize_t     sohm_btree_oh_size;
+
+    unsigned       use_shared = 0;
+    unsigned       use_btree = 0;
+    unsigned       open_close = 0;
+    h5_stat_size_t file_sizes[9];
+    unsigned       size_index = 0;
+    hsize_t        oh_sizes[3];
+    unsigned       oh_size_index = 0;
+
+    hsize_t        norm_oh_size;
+    hsize_t        sohm_oh_size;
+    hsize_t        sohm_btree_oh_size;
     h5_stat_size_t norm_empty_filesize;
     h5_stat_size_t sohm_empty_filesize;
     h5_stat_size_t sohm_btree_empty_filesize;
@@ -747,6 +802,7 @@ static void test_sohm_size1(void)
     h5_stat_size_t norm_final_filesize2;
     h5_stat_size_t sohm_final_filesize2;
     h5_stat_size_t sohm_btree_final_filesize2;
+
     H5O_info_t  oinfo;
     unsigned    num_indexes = 1;
     unsigned    index_flags = H5O_SHMESG_DTYPE_FLAG;
@@ -757,177 +813,103 @@ static void test_sohm_size1(void)
 
     MESSAGE(5, ("Testing that shared datatypes save space\n"));
 
-
     /* Create a FAPL with "semi" close degree, to detect dangling IDs */
     fapl_id = H5Pcreate(H5P_FILE_ACCESS);
     CHECK_I(fapl_id, "H5Pcreate");
-
     ret = H5Pset_fclose_degree(fapl_id, H5F_CLOSE_SEMI);
     CHECK_I(ret, "H5Pset_fclose_degree");
 
-    /* Create a file with SOHMs disabled and get its size */
-    fcpl_id = H5Pcreate(H5P_FILE_CREATE);
-    CHECK_I(fcpl_id, "H5Pcreate");
-
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, 0);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
-
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-
-    /* Get the file size */
-    norm_empty_filesize = h5_get_file_size(FILENAME, fapl_id);
-
-    /* Add a bunch of large datatypes to the file */
-    file = H5Fopen(FILENAME, H5F_ACC_RDWR, fapl_id);
-    CHECK_I(file, "H5Fopen");
-    file = size1_helper(file, FILENAME, fapl_id, 0);
-    CHECK_I(file, "size1_helper");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-
-    /* Get the new file size */
-    norm_final_filesize = h5_get_file_size(FILENAME, fapl_id);
-
-    /* Use the same property list to create a new file. */
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
-
-    ret = H5Pclose(fcpl_id);
-    CHECK_I(ret, "H5Pclose");
-
-    /* Add the same large datatypes, but keep closing and re-opening the file */
-    file = size1_helper(file, FILENAME, fapl_id, 1);
-    CHECK_I(file, "size1_helper");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-
-    /* Get the file size */
-    norm_final_filesize2 = h5_get_file_size(FILENAME, fapl_id);
-
-
-
-    /* Now do the same thing for a file with SOHMs enabled */
-    /* Create FCPL with SOHMs enabled */
-    fcpl_id = H5Pcreate(H5P_FILE_CREATE);
-    CHECK_I(fcpl_id, "H5Pcreate");
-
-    /* Tests one index holding only datatype messages */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, num_indexes);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, index_flags, min_mesg_size);
-    CHECK_I(ret, "H5Pset_shared_mesg_index");
-    ret = H5Pset_shared_mesg_phase_change(fcpl_id, list_max, btree_min);
-    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-
-    /* Create a file */
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
-
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-
-    sohm_empty_filesize = h5_get_file_size(FILENAME, fapl_id);
-
-    /* Add a bunch of datatypes to this file */
-    file = H5Fopen(FILENAME, H5F_ACC_RDWR, fapl_id);
-    CHECK_I(file, "H5Fopen");
-    file = size1_helper(file, FILENAME, fapl_id, 0);
-    CHECK_I(file, "size1_helper");
+    /* ----------------------------------------
+     * Run operations, accumulating file sizes to compare later.
+     */
+
+    for (use_shared = 0; use_shared < 2; use_shared++) {
+        for (use_btree = 0; use_btree < 2; use_btree++) {
+
+            /* cannot use btree indexing without shared messages; skip case */
+            if (use_btree && !use_shared)
+                continue;
+
+            fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+            CHECK_I(fcpl_id, "H5Pcreate");
+
+            if (use_shared) {
+                /* Tests one index holding only datatype messages */
+                ret = H5Pset_shared_mesg_nindexes(fcpl_id, num_indexes);
+                CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+                ret = H5Pset_shared_mesg_index(fcpl_id, 0, index_flags, min_mesg_size);
+                CHECK_I(ret, "H5Pset_shared_mesg_index");
+
+                if (use_btree) {
+                    ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
+                } else {
+                    ret = H5Pset_shared_mesg_phase_change(fcpl_id, list_max, btree_min);
+                }
+                CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+            } else {
+                ret = H5Pset_shared_mesg_nindexes(fcpl_id, 0);
+                CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+            }
+
+            file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
+            CHECK_I(file, "H5Fcreate");
+            ret = H5Fclose(file);
+            CHECK_I(ret, "H5Fclose");
 
-    /* Get the size of a dataset object header */
-    ret = H5Oget_info_by_name2(file, DSETNAME[0], &oinfo, H5O_INFO_HDR, H5P_DEFAULT);
-    CHECK_I(ret, "H5Oget_info_by_name");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-    sohm_oh_size = oinfo.hdr.space.total;
+            /* size of empty file */
+            file_sizes[size_index++] = h5_get_file_size(FILENAME, fapl_id);
 
-    /* Get the new file size */
-    sohm_final_filesize = h5_get_file_size(FILENAME, fapl_id);
+            /* size of populated file, with different populating behaviors */
+            for (open_close = 0; open_close < 2; open_close++)
+                file_sizes[size_index++] = getsize_testsize1(FILENAME, fcpl_id, fapl_id, open_close, &oinfo);
+            oh_sizes[oh_size_index++] = oinfo.hdr.space.total;
 
-    /* Use the same property list to create a new file. */
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
+            ret = H5Pclose(fcpl_id);
+            CHECK_I(ret, "H5Pclose");
+        } /* for btree/listed messages */
+    } /* for normal/shared messages */
 
-    ret = H5Pclose(fcpl_id);
+    ret = H5Pclose(fapl_id);
     CHECK_I(ret, "H5Pclose");
 
-    /* Add the same large datatypes, but keep closing and re-opening the file */
-    file = size1_helper(file, FILENAME, fapl_id, 1);
-    CHECK_I(file, "size1_helper");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-
-    /* Get the file size */
-    sohm_final_filesize2 = h5_get_file_size(FILENAME, fapl_id);
-
-
-
-    /* Create FCPL with SOHMs enabled that uses a B-tree index */
-    fcpl_id = H5Pcreate(H5P_FILE_CREATE);
-    CHECK_I(fcpl_id, "H5Pcreate");
-
-    /* Tests one index holding only datatype messages */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, num_indexes);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, index_flags, min_mesg_size);
-    CHECK_I(ret, "H5Pset_shared_mesg_index");
-    ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
-    CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-
-    /* Create a file */
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
-
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
+    /* sanity-check state of arrays */
+    VERIFY(9, size_index, "size_index");
+    VERIFY(3, oh_size_index, "oh_size_index");
 
-    sohm_btree_empty_filesize = h5_get_file_size(FILENAME, fapl_id);
-
-    /* Add a bunch of datatypes to this file */
-    file = H5Fopen(FILENAME, H5F_ACC_RDWR, fapl_id);
-    CHECK_I(file, "H5Fopen");
-    file = size1_helper(file, FILENAME, fapl_id, 0);
-    CHECK_I(file, "size1_helper");
-
-    /* Get the size of a dataset object header */
-    ret = H5Oget_info_by_name2(file, DSETNAME[0], &oinfo, H5O_INFO_HDR, H5P_DEFAULT);
-    CHECK_I(ret, "H5Oget_info_by_name");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
-    sohm_btree_oh_size = oinfo.hdr.space.total;
-
-    /* Get the new file size */
-    sohm_btree_final_filesize = h5_get_file_size(FILENAME, fapl_id);
-
-    /* Use the same property list to create a new file. */
-    file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
-    CHECK_I(file, "H5Fcreate");
-
-    ret = H5Pclose(fcpl_id);
-    CHECK_I(ret, "H5Pclose");
+    /* ----------------------------------------
+     * Check that all sizes make sense.
+     */
 
-    /* Add the same large datatypes, but keep closing and re-opening the file */
-    file = size1_helper(file, FILENAME, fapl_id, 1);
-    CHECK_I(file, "size1_helper");
-    ret = H5Fclose(file);
-    CHECK_I(ret, "H5Fclose");
+    /* Put result sizes into human-readable symbolic names.
+     * Order dependent on loop execution above.
+     */
+    norm_empty_filesize = file_sizes[0];
+    norm_final_filesize = file_sizes[1];
+    norm_final_filesize2 = file_sizes[2];
+    norm_oh_size = oh_sizes[0];
 
-    /* Get the file size */
-    sohm_btree_final_filesize2 = h5_get_file_size(FILENAME, fapl_id);
+    sohm_empty_filesize = file_sizes[3];
+    sohm_final_filesize = file_sizes[4];
+    sohm_final_filesize2 = file_sizes[5];
+    sohm_oh_size = oh_sizes[1];
 
+    sohm_btree_empty_filesize = file_sizes[6];
+    sohm_btree_final_filesize = file_sizes[7];
+    sohm_btree_final_filesize2 = file_sizes[8];
+    sohm_btree_oh_size = oh_sizes[2];
 
+    /* How the SOHM messages are stored shouldn't affect the
+     * size of the object header.
+     */
+    VERIFY(sohm_btree_oh_size, sohm_oh_size, "H5Oget_info_by_name");
 
-    /* Check that all sizes make sense */
+#if 0 /* TBD: lying comment or bug. See Jira HDFFV-10646 */
     /* Object headers in SOHM files should be smaller than normal object
-     * headers.  How the SOHM messages are stored shouldn't affect the
-     * size of the object header.
+     * headers.
      */
-    if(sohm_oh_size != sohm_btree_oh_size)
-        VERIFY(sohm_btree_oh_size, 1, "H5Oget_info_by_name");
+    if (sohm_oh_size >= norm_oh_size)
+        VERIFY(norm_oh_size, 1, "H5Oget_info_by_name");
+#endif /* Jira HDFFV-10646 */
 
     /* Both sohm files should be bigger than a normal file when empty.
      * It's hard to say whether a B-tree with no nodes allocated should be
@@ -942,23 +924,127 @@ static void test_sohm_size1(void)
         VERIFY(sohm_btree_empty_filesize, 1, "h5_get_file_size");
 
     /* When full, the sohm btree file should be smaller than the normal file.
-     * The sohm list file should be at least as small, since it doesn't need the
-     * overhead of a B-tree.
+     * The sohm list file should be at least as small, since it doesn't need
+     * the overhead of a B-tree.
      */
     if(sohm_btree_final_filesize >= norm_final_filesize)
         VERIFY(sohm_btree_final_filesize, 1, "h5_get_file_size");
     if(sohm_final_filesize > sohm_btree_final_filesize)
         VERIFY(sohm_final_filesize, 1, "h5_get_file_size");
 
-    /* This shouldn't change even if we open and close the file */
+    /* Comparative sizes shouldn't change even if we open and close the file
+     */
     if(sohm_btree_final_filesize2 >= norm_final_filesize2)
         VERIFY(sohm_btree_final_filesize2, 1, "h5_get_file_size");
     if(sohm_final_filesize2 > sohm_btree_final_filesize2)
         VERIFY(sohm_final_filesize2, 1, "h5_get_file_size");
 
+} /* test_sohm_size1 */
+
+
+/*---------------------------------------------------------------------------
+ * Function:    test_sohm_size_consistency_open_create
+ *
+ * Purpose:     Tests that header size is different depending on file open
+ *              procedure?
+ *              Uses "size1_helper" for file setup directed to a specific
+ *              file handle.
+ *
+ * Programmer:  Jacob Smith
+ *              2018 November 1
+ *
+ *---------------------------------------------------------------------------
+ */
+static void
+test_sohm_size_consistency_open_create(void)
+{
+    hid_t       file = -1;
+    hid_t       fcpl_id = -1;
+    hid_t       fapl_id = -1;
+    unsigned    use_btree;
+    hsize_t     oh_size_open;
+    hsize_t     oh_size_create;
+    H5O_info_t  oinfo;
+    unsigned    num_indexes = 1;
+    unsigned    index_flags = H5O_SHMESG_DTYPE_FLAG;
+    unsigned    min_mesg_size = 50;
+    unsigned    list_max = 11;
+    unsigned    btree_min = 10;
+    herr_t      ret;
+
+    MESSAGE(5, \
+    ("Testing that header size is consistent between H5Fopen and H5Fcreate\n"));
+
+    /* Create a FAPL with "semi" close degree, to detect dangling IDs */
+    fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+    CHECK_I(fapl_id, "H5Pcreate");
+    ret = H5Pset_fclose_degree(fapl_id, H5F_CLOSE_SEMI);
+    CHECK_I(ret, "H5Pset_fclose_degree");
+
+    for (use_btree = 0; use_btree < 2; use_btree++) {
+        /* Create FCPL with SOHMs enabled
+         */
+        fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+        CHECK_I(fcpl_id, "H5Pcreate");
+        ret = H5Pset_shared_mesg_nindexes(fcpl_id, num_indexes);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 0, index_flags, min_mesg_size);
+        CHECK_I(ret, "H5Pset_shared_mesg_index");
+        if (use_btree) {
+            MESSAGE(5, ("----testing with btree index----\n"));
+            ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
+            CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+        } else {
+            MESSAGE(5, ("----testing with normal index----\n"));
+            ret = H5Pset_shared_mesg_phase_change(fcpl_id, list_max, btree_min);
+            CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
+        }
+
+        /* Create empty file */
+        file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
+        CHECK_I(file, "H5Fcreate");
+        ret = H5Fclose(file);
+        CHECK_I(ret, "H5Fclose");
+
+        /* Test Open/Write
+         * Add messages to previously-created file */
+        file = H5Fopen(FILENAME, H5F_ACC_RDWR, fapl_id);
+        CHECK_I(file, "H5Fopen");
+        file = size1_helper(file, FILENAME, fapl_id, 0);
+        CHECK_I(file, "size1_helper");
+
+        /* Get the size of a dataset object header */
+        ret = H5Oget_info_by_name2(file, DSETNAME[0], &oinfo, H5O_INFO_HDR, H5P_DEFAULT);
+        CHECK_I(ret, "H5Oget_info_by_name");
+        oh_size_open = oinfo.hdr.space.total;
+
+        ret = H5Fclose(file);
+        CHECK_I(ret, "H5Fclose");
+
+        /* Test Create/Write
+         * Add messages to a newly-created file */
+        file = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, fapl_id);
+        CHECK_I(file, "H5Fcreate");
+        file = size1_helper(file, FILENAME, fapl_id, 0);
+        CHECK_I(file, "size1_helper");
+
+        /* Get the size of a dataset object header */
+        ret = H5Oget_info_by_name2(file, DSETNAME[0], &oinfo, H5O_INFO_HDR, H5P_DEFAULT);
+        CHECK_I(ret, "H5Oget_info_by_name");
+        oh_size_create = oinfo.hdr.space.total;
+
+        ret = H5Fclose(file);
+        CHECK_I(ret, "H5Fclose");
+
+        VERIFY(oh_size_create, oh_size_open, "H5Oget_info_by_name2");
+
+        ret = H5Pclose(fcpl_id);
+        CHECK_I(ret, "H5Pclose");
+    } /* for normal/btree indexing */
+
     ret = H5Pclose(fapl_id);
     CHECK_I(ret, "H5Pclose");
-}
+} /* test_sohm_size_consistency_open_create */
 
 
 /*-------------------------------------------------------------------------
@@ -966,149 +1052,110 @@ static void test_sohm_size1(void)
  *
  * Purpose:     Given an fcpl, tests creating attributes with and without
  *              committed datatypes.
+ *              Verify that an attribute can be written and read back.
+ *              Tests attribute on a Group.
+ *              Tests committed and non-committed datatypes.
+ *              Tests attribute access through `H5Aopen()`.
  *
  * Programmer:  James Laird
  *              Thursday, November 30, 2006
  *
  *-------------------------------------------------------------------------
  */
-static void sohm_attr_helper(hid_t fcpl_id)
+static void
+sohm_attr_helper(hid_t fcpl_id)
 {
     hid_t file_id;
-    hid_t type_id;
     hid_t space_id;
-    hid_t group_id;
-    hid_t attr_id, attr_id2;
     hsize_t dims = 2;
     int wdata[2] = {7, 42};
     int rdata[2];
     herr_t ret;
     size_t x;
+    unsigned op_index=0;
+#define TSOHM_SAH_OP_COUNT 3
+    const char *groupnames[TSOHM_SAH_OP_COUNT] = {
+        "group_for_nothing_special",
+        "group_for_commited_dtype",
+        "group_for_commited_dtype_and_other_ID_access",
+    };
 
-    /*----------------------------------------------------------------------------
-     *    Test attribute with transient datatype
-     */
-    /* Create a file using the fcpl */
     file_id = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
     CHECK_I(file_id, "H5Fcreate");
 
-    /* Create a normal datatype and dataset */
-    type_id = H5Tcopy(H5T_NATIVE_INT);
-    CHECK_I(type_id, "H5Tcopy");
     space_id = H5Screate_simple(1, &dims, &dims);
     CHECK_I(space_id, "H5Screate_simple");
 
-    /* Create and verify an attribute on a group */
-    group_id = H5Gcreate2(file_id, "group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(group_id, "H5Gcreate2");
-    attr_id = H5Acreate2(group_id, "attribute", type_id, space_id, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(attr_id, "H5Acreate2");
-    ret = H5Awrite(attr_id, H5T_NATIVE_INT, wdata);
-    CHECK_I(ret, "H5Awrite");
-
-    /* Close the datatype and group */
-    ret = H5Tclose(type_id);
-    CHECK_I(ret, "H5Tclose");
-    ret = H5Gclose(group_id);
-    CHECK_I(ret, "H5Gclose");
-
-    /* Flush the file to force data to be written */
-    ret = H5Fflush(file_id, H5F_SCOPE_GLOBAL);
-    CHECK_I(ret, "H5Fflush");
-
-    /* Verify */
-    HDmemset(rdata, 0, sizeof(rdata));
-    ret = H5Aread(attr_id, H5T_NATIVE_INT, rdata);
-    CHECK_I(ret, "H5Aread");
-    for(x = 0; x < (size_t)dims; ++x)
-        VERIFY(rdata[x], wdata[x], "H5Aread");
-
-    /* Cleanup */
-    ret = H5Aclose(attr_id);
-    CHECK_I(ret, "H5Aclose");
-
-    /*----------------------------------------------------------------------------
-     *    Test attribute with committed datatype
+    /* loop:
+     * 0 - nothing special
+     * 1 - committed datatype
+     * 2 - committed datatype, read through second ID
      */
-    /* Repeat with a committed datatype */
-    type_id = H5Tcopy(H5T_NATIVE_INT);
-    CHECK_I(type_id, "H5Tcopy");
-    ret = H5Tcommit2(file_id, "datatype", type_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(ret, "H5Tcommit2");
+    for (op_index = 0; op_index < TSOHM_SAH_OP_COUNT; op_index++) {
+        hid_t type_id  = -1;
+        hid_t group_id = -1;
+        hid_t attr_id  = -1;
+        hid_t attr_id2 = -1;
+        hid_t attr_read_id;
 
-    /* Create and verify an attribute */
-    group_id = H5Gcreate2(file_id, "another_group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(group_id, "H5Gcreate2");
-    attr_id = H5Acreate2(group_id, "attribute", type_id, space_id, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(attr_id, "H5Acreate2");
-    ret = H5Awrite(attr_id, H5T_NATIVE_INT, wdata);
-    CHECK_I(ret, "H5Awrite");
-
-    /* Close the datatype and group */
-    ret = H5Tclose(type_id);
-    CHECK_I(ret, "H5Tclose");
-    ret = H5Gclose(group_id);
-    CHECK_I(ret, "H5Gclose");
+        /* create group in file with name unique to op_index */
+        group_id = H5Gcreate2(file_id, groupnames[op_index], H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+        CHECK_I(group_id, "H5Gcreate2");
 
-    /* Flush the file to force data to be written */
-    ret = H5Fflush(file_id, H5F_SCOPE_GLOBAL);
-    CHECK_I(ret, "H5Fflush");
+        type_id = H5Tcopy(H5T_NATIVE_INT);
+        CHECK_I(type_id, "H5Tcopy");
 
-    /* Verify */
-    HDmemset(rdata, 0, sizeof(rdata));
-    ret = H5Aread(attr_id, H5T_NATIVE_INT, rdata);
-    CHECK_I(ret, "H5Aread");
-    for(x = 0; x < (size_t)dims; ++x)
-        VERIFY(rdata[x], wdata[x], "H5Aread");
-
-    /* Cleanup */
-    ret = H5Aclose(attr_id);
-    CHECK_I(ret, "H5Aclose");
-
-    /*----------------------------------------------------------------------------
-     *    Test attribute operation with two ID handles
-     */
-    /* Create and verify an attribute */
-    group_id = H5Gcreate2(file_id, "yet_another_group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(group_id, "H5Gcreate2");
-
-    attr_id = H5Acreate2(group_id, "attribute", H5T_NATIVE_INT, space_id, H5P_DEFAULT, H5P_DEFAULT);
-    CHECK_I(attr_id, "H5Acreate2");
+        /* Commit the datatype for the latter iterations.
+         * Only do this ONCE.
+         */
+        if (op_index == 1) {
+            ret = H5Tcommit2(file_id, "datatype", type_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+            CHECK_I(ret, "H5Tcommit2");
+        }
 
-    /* Open the attribute to get another handle */
-    attr_id2 = H5Aopen(group_id, "attribute", H5P_DEFAULT);
-    CHECK_I(attr_id2, "H5Aopen");
+        attr_id = H5Acreate2(group_id, "attribute", type_id, space_id, H5P_DEFAULT, H5P_DEFAULT);
+        CHECK_I(attr_id, "H5Acreate2");
 
-    ret = H5Awrite(attr_id, H5T_NATIVE_INT, wdata);
-    CHECK_I(ret, "H5Awrite");
+        if (op_index == 2) {
+            /* Open the attribute to get another handle */
+            attr_id2 = H5Aopen(group_id, "attribute", H5P_DEFAULT);
+            CHECK_I(attr_id2, "H5Aopen");
+        }
 
-    /* Close the group */
-    ret = H5Gclose(group_id);
-    CHECK_I(ret, "H5Gclose");
+        ret = H5Awrite(attr_id, H5T_NATIVE_INT, wdata);
+        CHECK_I(ret, "H5Awrite");
 
-    /* Flush the file to force data to be written */
-    ret = H5Fflush(file_id, H5F_SCOPE_GLOBAL);
-    CHECK_I(ret, "H5Fflush");
+        ret = H5Gclose(group_id);
+        CHECK_I(ret, "H5Gclose");
+        ret = H5Tclose(type_id);
+        CHECK_I(ret, "H5Tclose");
 
-    /* Verify the data with another ID handle */
-    HDmemset(rdata, 0, sizeof(rdata));
-    ret = H5Aread(attr_id2, H5T_NATIVE_INT, rdata);
-    CHECK_I(ret, "H5Aread");
+        /* Flush the file to force data to be written */
+        ret = H5Fflush(file_id, H5F_SCOPE_GLOBAL);
+        CHECK_I(ret, "H5Fflush");
 
-    for(x = 0; x < (size_t)dims; ++x)
-        VERIFY(rdata[x], wdata[x], "H5Aread");
+        /* Verify */
+        attr_read_id = (op_index == 2) ? attr_id2 : attr_id;
+        HDmemset(rdata, 0, sizeof(rdata));
+        ret = H5Aread(attr_read_id, H5T_NATIVE_INT, rdata);
+        CHECK_I(ret, "H5Aread");
+        for(x = 0; x < (size_t)dims; ++x)
+            VERIFY(rdata[x], wdata[x], "H5Aread");
 
-    /* Cleanup */
-    ret = H5Aclose(attr_id);
-    CHECK_I(ret, "H5Aclose");
-    ret = H5Aclose(attr_id2);
-    CHECK_I(ret, "H5Aclose");
+        ret = H5Aclose(attr_id);
+        CHECK_I(ret, "H5Aclose");
+        if (attr_id2 > -1 ) {
+            ret = H5Aclose(attr_id2);
+            CHECK_I(ret, "H5Aclose");
+        }
+    } /* for each attribute operation */
 
     ret = H5Sclose(space_id);
     CHECK_I(ret, "H5Sclose");
     ret = H5Fclose(file_id);
     CHECK_I(ret, "H5Fclose");
-}
+#undef TSOHM_SAH_OP_COUNT
+} /* sohm_attr_helper */
 
 
 /*-------------------------------------------------------------------------
@@ -1125,101 +1172,160 @@ static void sohm_attr_helper(hid_t fcpl_id)
  *
  *-------------------------------------------------------------------------
  */
-static void test_sohm_attrs(void)
+static void
+test_sohm_attrs(void)
 {
     hid_t fcpl_id;
+    unsigned i = 0;
+#define TSOHM_TSA_NFLAGS_1 7
+    unsigned flags1[TSOHM_TSA_NFLAGS_1] = {
+        H5O_SHMESG_ATTR_FLAG,
+        H5O_SHMESG_SDSPACE_FLAG,
+        H5O_SHMESG_DTYPE_FLAG,
+        H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_SDSPACE_FLAG,
+        H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG,
+        H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_DTYPE_FLAG,
+        H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG,
+    };
+#define TSOHM_TSA_NFLAGS_2 6
+    unsigned flags2[TSOHM_TSA_NFLAGS_2][2] = {
+        {   H5O_SHMESG_ATTR_FLAG,
+            H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG,
+        },
+        {   H5O_SHMESG_SDSPACE_FLAG,
+            H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_DTYPE_FLAG,
+        },
+        {   H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_SDSPACE_FLAG,
+        },
+        {   H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG,
+        },
+        {   H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_SDSPACE_FLAG,
+        },
+        {   H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_SDSPACE_FLAG,
+            H5O_SHMESG_DTYPE_FLAG,
+        },
+    };
+#define TSOHM_TSA_NFLAGS_3 5
+    unsigned flags3[TSOHM_TSA_NFLAGS_3][3] = {
+        {   H5O_SHMESG_ATTR_FLAG,
+            H5O_SHMESG_SDSPACE_FLAG,
+            H5O_SHMESG_DTYPE_FLAG,
+        },
+        {   H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG,
+            H5O_SHMESG_SDSPACE_FLAG,
+        },
+        {   H5O_SHMESG_SDSPACE_FLAG,
+            H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG,
+        },
+        {   0, /* first index does not hold a shared message type? */
+            H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG,
+        },
+        {   0, /* missing SDSPACE flag */
+            H5O_SHMESG_DTYPE_FLAG,
+            H5O_SHMESG_ATTR_FLAG,
+        },
+    };
     herr_t ret;
 
     MESSAGE(5, ("Testing that shared messages work with attributes\n"));
 
-    /* Create an fcpl with no shared messages */
+    /* No shared messages
+     */
     fcpl_id = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl_id, "H5Pcreate");
     ret = H5Pset_shared_mesg_nindexes(fcpl_id, 0);
     CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
 
-    /* Make sure attributes can be read with these settings (they'd better!) */
-    sohm_attr_helper(fcpl_id);
-
-
-    /* Run tests with only one kind of message to be shared */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ATTR_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    /* Verify */
-    sohm_attr_helper(fcpl_id);
-
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_SDSPACE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    sohm_attr_helper(fcpl_id);
-
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_DTYPE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    sohm_attr_helper(fcpl_id);
-
-
-    /* Run with any two types shared */
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
     sohm_attr_helper(fcpl_id);
 
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_DTYPE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    sohm_attr_helper(fcpl_id);
-
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_ATTR_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    sohm_attr_helper(fcpl_id);
-
-
-    /* Run test with all three kinds of message shared */
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_SDSPACE_FLAG | H5O_SHMESG_DTYPE_FLAG | H5O_SHMESG_ATTR_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+    ret = H5Pclose(fcpl_id);
+    CHECK_I(ret, "H5Pclose");
 
-    sohm_attr_helper(fcpl_id);
+    /* One shared message index
+     */
+    for (i=0; i < TSOHM_TSA_NFLAGS_1; i++) {
+        fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+        CHECK_I(fcpl_id, "H5Pcreate");
+        ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 0, flags1[i], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
 
+        sohm_attr_helper(fcpl_id);
 
-    /* Try using two indexes */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ATTR_FLAG | H5O_SHMESG_DTYPE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 1, H5O_SHMESG_SDSPACE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pclose(fcpl_id);
+        CHECK_I(ret, "H5Pclose");
+    }
 
-    sohm_attr_helper(fcpl_id);
+    /* two shared message indices
+     */
+    for (i=0; i < TSOHM_TSA_NFLAGS_2; i++) {
+        fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+        CHECK_I(fcpl_id, "H5Pcreate");
+        ret = H5Pset_shared_mesg_nindexes(fcpl_id, 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 0, flags2[i][0], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 1, flags2[i][1], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
 
-    ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_DTYPE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        sohm_attr_helper(fcpl_id);
 
-    sohm_attr_helper(fcpl_id);
+        ret = H5Pclose(fcpl_id);
+        CHECK_I(ret, "H5Pclose");
+    }
 
-    ret = H5Pset_shared_mesg_index(fcpl_id, 1, H5O_SHMESG_ATTR_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+    /* duplicate flags in separate indices causes problems
+     */
+    H5E_BEGIN_TRY {
+        fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+        CHECK_I(fcpl_id, "H5Pcreate");
+        ret = H5Pset_shared_mesg_nindexes(fcpl_id, 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ATTR_FLAG, 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 1, H5O_SHMESG_ATTR_FLAG, 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+
+        ret = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
+        VERIFY(ret, -1, "H5Fcreate");
+
+        ret = H5Pclose(fcpl_id);
+        CHECK_I(ret, "H5Pclose");
+    } H5E_END_TRY;
 
-    sohm_attr_helper(fcpl_id);
+    /* three shared message indices
+     */
+    for (i=0; i < TSOHM_TSA_NFLAGS_3; i++) {
+        fcpl_id = H5Pcreate(H5P_FILE_CREATE);
+        CHECK_I(fcpl_id, "H5Pcreate");
+        ret = H5Pset_shared_mesg_nindexes(fcpl_id, 3);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 0, flags3[i][0], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 1, flags3[i][1], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pset_shared_mesg_index(fcpl_id, 2, flags3[i][2], 2);
+        CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
 
+        sohm_attr_helper(fcpl_id);
 
-    /* One index for each kind of message */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, 3);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-    ret = H5Pset_shared_mesg_index(fcpl_id, 2, H5O_SHMESG_SDSPACE_FLAG, 2);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
+        ret = H5Pclose(fcpl_id);
+        CHECK_I(ret, "H5Pclose");
+    }
 
-    sohm_attr_helper(fcpl_id);
+#undef TSOHM_TSA_NFLAGS_1
+#undef TSOHM_TSA_NFLAGS_2
+#undef TSOHM_TSA_NFLAGS_3
 
+} /* test_sohm_attrs */
 
-    /* Close the FCPL */
-    ret = H5Pclose(fcpl_id);
-    CHECK_I(ret, "H5Pclose");
-}
 
 /*-------------------------------------------------------------------------
  * Function:    size2_verify_plist1
@@ -1233,7 +1339,8 @@ static void test_sohm_attrs(void)
  *
  *-------------------------------------------------------------------------
  */
-static void size2_verify_plist1(hid_t plist)
+static void
+size2_verify_plist1(hid_t plist)
 {
     size_t cd_nelmts;
     unsigned int cd_value;
@@ -1281,7 +1388,8 @@ static void size2_verify_plist1(hid_t plist)
 
     ret = H5Tclose(dtype1_id);
     CHECK_I(ret, "H5Tclose");
-}
+} /* size2_verify_plist1 */
+
 
 /*-------------------------------------------------------------------------
  * Function:    size2_verify_plist2
@@ -1295,7 +1403,8 @@ static void size2_verify_plist1(hid_t plist)
  *
  *-------------------------------------------------------------------------
  */
-static void size2_verify_plist2(hid_t plist)
+static void
+size2_verify_plist2(hid_t plist)
 {
     size_t cd_nelmts;
     unsigned int cd_value;
@@ -1352,7 +1461,7 @@ static void size2_verify_plist2(hid_t plist)
 
     ret = H5Tclose(dtype2_id);
     CHECK_I(ret, "H5Tclose");
-}
+} /* size2_verify_plist2 */
 
 #ifdef NOT_NOW
 
@@ -1382,7 +1491,7 @@ size2_dump_struct(const char *name, size2_helper_struct *sizes)
   printf("   interleaved: %llu \tdelta: %llu\n", (unsigned long long)sizes->interleaved, (unsigned long long)(sizes->interleaved - sizes->dsets2));
   printf("    attributes: %llu \tdelta: %llu\n", (unsigned long long)sizes->attrs1, (unsigned long long)(sizes->attrs1 - sizes->interleaved));
   printf("  attributes 2: %llu \tdelta: %llu\n", (unsigned long long)sizes->attrs2, (unsigned long long)(sizes->attrs2 - sizes->attrs1));
-}
+} /* size2_dump_struct */
 #endif /* NOT_NOW */
 
 
@@ -1573,15 +1682,14 @@ size2_helper(hid_t fcpl_id, int test_file_closing, size2_helper_struct *ret_size
     ret_sizes->dsets1 = h5_get_file_size(FILENAME, H5P_DEFAULT);
 
 
-    /* Now create a new group filled with datasets that use all different messages */
+    /* Create new group filled with datasets that use all different messages */
     file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
     CHECK_I(file_id, "H5Fopen");
     group_id = H5Gcreate2(file_id, "group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     CHECK_I(group_id, "H5Gcreate2");
 
     /* Create NUM_DATASETS datasets in the new group */
-    for(x=0; x<NUM_DATASETS; ++x)
-    {
+    for(x=0; x<NUM_DATASETS; ++x) {
         dset_id = H5Dcreate2(group_id, DSETNAME[x], dtype2_id, dspace2_id, H5P_DEFAULT, dcpl2_id, H5P_DEFAULT);
         CHECK_I(dset_id, "H5Dcreate2");
 
@@ -1768,7 +1876,7 @@ size2_helper(hid_t fcpl_id, int test_file_closing, size2_helper_struct *ret_size
     CHECK_I(ret, "H5Pclose");
 
     return 0;
-}
+} /* size2_helper */
 
 
 /*-------------------------------------------------------------------------
@@ -1785,7 +1893,8 @@ size2_helper(hid_t fcpl_id, int test_file_closing, size2_helper_struct *ret_size
  *
  *-------------------------------------------------------------------------
  */
-static void size2_verify(void)
+static void
+size2_verify(void)
 {
     hid_t file_id = -1;
     hid_t dset_id=-1;
@@ -1968,7 +2077,7 @@ static void size2_verify(void)
     CHECK_I(ret, "H5Gclose");
     ret = H5Fclose(file_id);
     CHECK_I(ret, "H5Fclose");
-}
+} /* size2_verify */
 
 
 /*-------------------------------------------------------------------------
@@ -1993,7 +2102,8 @@ static void size2_verify(void)
  *
  *-------------------------------------------------------------------------
  */
-static void test_sohm_size2(int close_reopen)
+static void
+test_sohm_size2(int close_reopen)
 {
     hid_t       fcpl_id = -1;
     /* Sizes for file with no shared messages at all */
@@ -2585,7 +2695,7 @@ static void test_sohm_size2(int close_reopen)
         VERIFY(0, 1, "h5_get_file_size");
     if((h5_stat_size_t)((float)share_tiny_index.attrs2 * OVERHEAD_ALLOWED) < type_space_index.attrs2)
         VERIFY(0, 1, "h5_get_file_size");
-} /* end test_sohm_size2() */
+} /* test_sohm_size2 */
 
 
 /*-------------------------------------------------------------------------
@@ -2601,27 +2711,22 @@ static void test_sohm_size2(int close_reopen)
  *
  *-------------------------------------------------------------------------
  */
-static void delete_helper_write(hid_t file_id, hid_t *dspace_id, hid_t *dcpl_id, int x)
+static void
+delete_helper_write(hid_t file_id, hid_t *dspace_id, hid_t *dcpl_id, int x)
 {
-    hid_t dset_id = -1;
-    hid_t attr_id = -1;
-    char wdata;
+    hid_t  dset_id = -1;
+    hid_t  attr_id = -1;
+    char   wdata;
     herr_t ret;
 
-    /* Create dataset */
     dset_id = H5Dcreate2(file_id, DSETNAME[x], H5T_NATIVE_CHAR, dspace_id[x], H5P_DEFAULT, dcpl_id[x], H5P_DEFAULT);
     CHECK_I(dset_id, "H5Dcreate2");
-
-    /* Write data to dataset */
     wdata = (char)(x + 'a');
     ret = H5Dwrite(dset_id, H5T_NATIVE_CHAR, dspace_id[x], dspace_id[x], H5P_DEFAULT, &wdata);
     CHECK_I(ret, "H5Dwrite");
 
-    /* Create an attribute on the dataset. */
     attr_id = H5Acreate2(dset_id, "attr_name", H5T_NATIVE_CHAR, dspace_id[x], H5P_DEFAULT, H5P_DEFAULT);
     CHECK_I(attr_id, "H5Acreate2");
-
-    /* Write to attribute */
     ret = H5Awrite(attr_id, H5T_NATIVE_CHAR, &wdata);
     CHECK_I(ret, "H5Awrite");
 
@@ -2629,7 +2734,7 @@ static void delete_helper_write(hid_t file_id, hid_t *dspace_id, hid_t *dcpl_id,
     CHECK_I(ret, "H5Aclose");
     ret = H5Dclose(dset_id);
     CHECK_I(ret, "H5Dclose");
-}
+} /* delete_helper_write */
 
 
 /*-------------------------------------------------------------------------
@@ -2645,39 +2750,33 @@ static void delete_helper_write(hid_t file_id, hid_t *dspace_id, hid_t *dcpl_id,
  *
  *-------------------------------------------------------------------------
  */
-static void delete_helper_read(hid_t file_id, hid_t *dspace_id, int x)
+static void
+delete_helper_read(hid_t file_id, hid_t *dspace_id, int x)
 {
     hid_t dset_id = -1;
     hid_t attr_id = -1;
     char rdata;
     herr_t ret;
 
-    /* Open dataset */
     dset_id = H5Dopen2(file_id, DSETNAME[x], H5P_DEFAULT);
     CHECK_I(dset_id, "H5Dopen2");
-
-    /* Read */
     rdata = '\0';
     ret = H5Dread(dset_id, H5T_NATIVE_CHAR, dspace_id[x], dspace_id[x], H5P_DEFAULT, &rdata);
     CHECK_I(ret, "H5Dread");
     VERIFY(rdata, (x + 'a'), "H5Dread");
 
-    /* Open attribute */
     attr_id = H5Aopen(dset_id, "attr_name", H5P_DEFAULT);
     CHECK_I(attr_id, "H5Aopen");
-
-    /* Read */
     rdata = '\0';
     ret = H5Aread(attr_id, H5T_NATIVE_CHAR, &rdata);
     CHECK_I(ret, "H5Dread");
     VERIFY(rdata, (x + 'a'), "H5Dread");
 
-    /* Cleanup */
     ret = H5Aclose(attr_id);
     CHECK_I(ret, "H5Aclose");
     ret = H5Dclose(dset_id);
     CHECK_I(ret, "H5Dclose");
-}
+} /* delete_helper_read */
 
 
 /*-------------------------------------------------------------------------
@@ -2701,7 +2800,8 @@ static void delete_helper_read(hid_t file_id, hid_t *dspace_id, int x)
  *
  *-------------------------------------------------------------------------
  */
-static void delete_helper(hid_t fcpl_id, hid_t *dspace_id, hid_t *dcpl_id)
+static void
+delete_helper(hid_t fcpl_id, hid_t *dspace_id, hid_t *dcpl_id)
 {
     hid_t file_id=-1;
     int x;
@@ -2765,7 +2865,7 @@ static void delete_helper(hid_t fcpl_id, hid_t *dspace_id, hid_t *dcpl_id)
         VERIFY(norm_filesize, deleted_filesize, "h5_get_file_size");
     if(deleted_filesize > (h5_stat_size_t)((float)norm_filesize * OVERHEAD_ALLOWED))
         VERIFY(deleted_filesize, norm_filesize, "h5_get_file_size");
-}
+} /* delete_helper */
 
 
 /*-------------------------------------------------------------------------
@@ -2799,6 +2899,8 @@ test_sohm_delete(void)
     hsize_t dims[] = DELETE_DIMS;
     herr_t ret;
 
+    MESSAGE(5, ("Testing deletion of SOHMs\n"));
+
     /* Create a number of different dataspaces.
      * For simplicity, each dataspace has only one element.
      */
@@ -2910,17 +3012,18 @@ test_sohm_delete(void)
         ret = H5Pclose(dcpl_id[x]);
         CHECK_I(ret, "H5Pclose");
     } /* end for */
-} /* end test_sohm_delete() */
+} /* test_sohm_delete */
 
 
 /*-------------------------------------------------------------------------
- * Function:    test_sohm_delete_revert_helper
+ * Function:    verify_dset_create_and_delete_does_not_grow_file
  *
  * Purpose:     Tests that shared object header message deletion returns
  *              the file to its previous state using the supplied FCPL.
  *
- *              Creates shared messages and then deletes them.  Ensures
- *              that the file has not grown in size.
+ *              Creates a file according to the supplied FCPL,
+ *              then creates datasets and deletes them.
+ *              Done in two passes: once with one dataset, once with two.
  *
  * Programmer:  James Laird
  *              Wednesday, January 3, 2007
@@ -2930,7 +3033,7 @@ test_sohm_delete(void)
  *-------------------------------------------------------------------------
  */
 static int
-test_sohm_delete_revert_helper(hid_t fcpl_id)
+verify_dset_create_and_delete_does_not_grow_file(hid_t fcpl_id)
 {
     hid_t file_id;
     hid_t dspace_id;
@@ -3017,13 +3120,14 @@ test_sohm_delete_revert_helper(hid_t fcpl_id)
         return(0);
     else
         return(-1);
-} /* test_sohm_delete_revert_helper() */
+} /* verify_dset_create_and_delete_does_not_grow_file */
 
 
 /*-------------------------------------------------------------------------
  * Function:    test_sohm_delete_revert
  *
- * Purpose:     Calls test_sohm_delete_revert_helper with different FCPLs.
+ * Purpose:     Verifies that creation and deletion of datasets with shared
+ *              message headers will not increase file size.
  *
  * Programmer:  James Laird
  *              Wednesday, January 3, 2007
@@ -3038,6 +3142,8 @@ test_sohm_delete_revert(void)
     hid_t fcpl_id;
     herr_t ret;
 
+    MESSAGE(5, ("Testing that file reverts to original size on SOHM deletion\n"));
+
     /* Create an fcpl with messages in two indexes */
     fcpl_id = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl_id, "H5Pcreate");
@@ -3049,14 +3155,14 @@ test_sohm_delete_revert(void)
     CHECK_I(ret, "H5Pset_shared_mesg_index");
 
     /* Call the helper function to test this FCPL. */
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
     /* Try using B-trees */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
 
     /* Try sharing all messages */
@@ -3067,14 +3173,14 @@ test_sohm_delete_revert(void)
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 10, 5);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
     /* Try using B-trees */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
     /* There should be at least two messages in the test (datatype and
      * dataspace).  Use an index that will transition from a list to
@@ -3082,8 +3188,8 @@ test_sohm_delete_revert(void)
      */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 1, 2);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
 
     /* Try with shared messages enabled, but when messages are too big
@@ -3091,16 +3197,16 @@ test_sohm_delete_revert(void)
      */
     ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ALL_FLAG, 35);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
-    ret = test_sohm_delete_revert_helper(fcpl_id);
-    CHECK_I(ret, "test_sohm_delete_revert_helper");
+    ret = verify_dset_create_and_delete_does_not_grow_file(fcpl_id);
+    CHECK_I(ret, "verify_dset_create_and_delete_does_not_grow_file");
 
     ret = H5Pclose(fcpl_id);
     CHECK_I(ret, "H5Pclose");
-}
+} /* test_sohm_delete_revert */
 
 
 /*-------------------------------------------------------------------------
- * Function:    test_sohm_extlink_helper
+ * Function:    verify_dset_create_and_open_through_extlink_with_sohm
  *
  * Purpose:     Tests that a dataset created through an external link can
  *              be opened (that shared messages were created or not and
@@ -3113,7 +3219,8 @@ test_sohm_delete_revert(void)
  *
  *-------------------------------------------------------------------------
  */
-static void test_sohm_extlink_helper(hid_t src_fcpl_id, hid_t dst_fcpl_id)
+static void
+verify_dset_create_and_open_through_extlink_with_sohm(hid_t src_fcpl_id, hid_t dst_fcpl_id)
 {
     hid_t src_file_id = -1;
     hid_t dst_file_id = -1;
@@ -3164,7 +3271,7 @@ static void test_sohm_extlink_helper(hid_t src_fcpl_id, hid_t dst_fcpl_id)
     CHECK_I(ret, "H5Dclose");
     ret = H5Fclose(dst_file_id);
     CHECK_I(ret, "H5Fclose");
-}
+} /* verify_dset_create_and_open_through_extlink_with_sohm */
 
 
 /*-------------------------------------------------------------------------
@@ -3186,7 +3293,8 @@ test_sohm_extlink(void)
     hid_t fcpl_id = -1;
     herr_t ret;
 
-    /* Create fcpl */
+    MESSAGE(5, ("Testing SOHM creation through external links\n"));
+
     fcpl_id = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl_id, "H5Pcreate");
     ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1);
@@ -3194,20 +3302,17 @@ test_sohm_extlink(void)
     ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ALL_FLAG, 16);
     CHECK_I(ret, "H5Pset_shared_mesg_index");
 
-    /* Test using external links when the source or destination file uses
-     * shared messages
-     */
-    test_sohm_extlink_helper(fcpl_id, H5P_DEFAULT);
-    test_sohm_extlink_helper(H5P_DEFAULT, fcpl_id);
-    test_sohm_extlink_helper(fcpl_id, fcpl_id);
+    verify_dset_create_and_open_through_extlink_with_sohm(fcpl_id, H5P_DEFAULT);
+    verify_dset_create_and_open_through_extlink_with_sohm(H5P_DEFAULT, fcpl_id);
+    verify_dset_create_and_open_through_extlink_with_sohm(fcpl_id, fcpl_id);
 
     ret = H5Pclose(fcpl_id);
     CHECK_I(ret, "H5Pclose");
-}
+} /* test_sohm_extlink */
 
 
 /*-------------------------------------------------------------------------
- * Function:    test_sohm_extend_dset_helper
+ * Function:    verify_dataset_extension
  *
  * Purpose:     Tests extending a dataset's dataspace when sharing is
  *              enabled.
@@ -3223,7 +3328,7 @@ test_sohm_extlink(void)
  *-------------------------------------------------------------------------
  */
 static int
-test_sohm_extend_dset_helper(hid_t fcpl_id, hbool_t close_reopen)
+verify_dataset_extension(hid_t fcpl_id, hbool_t close_reopen)
 {
     hid_t file_id = -1;
     hid_t orig_space_id = -1;
@@ -3236,13 +3341,98 @@ test_sohm_extend_dset_helper(hid_t fcpl_id, hbool_t close_reopen)
     hsize_t out_dims[2];
     hsize_t out_maxdims[2];
     int x;
-    int old_nerrs;              /* Number of errors when entering this routine */
+    int old_nerrs;           /* Number of errors when entering this routine */
     herr_t ret;
 
-    /* Retrieve the current # of reported errors */
+    hsize_t *space_dims[3];
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ * Macro:      TSOHM_VDE_VERIFY_SPACES
+ *
+ * Purpose:    Encapsulate a common pattern
+ *             Open, read-verify, and close the dataspaces for datasets 1-3
+ *
+ * Programmer: Jacob Smith
+ *             2018 November 5
+ * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ */
+#define TSOHM_VDE_VERIFY_SPACES(dims)                                     \
+{                                                                         \
+    /* Open dataspaces                                                    \
+     */                                                                   \
+    space1_id = H5Dget_space(dset1_id);                                   \
+    CHECK_I(space1_id, "H5Dget_space");                                   \
+    space2_id = H5Dget_space(dset2_id);                                   \
+    CHECK_I(space2_id, "H5Dget_space");                                   \
+    space3_id = H5Dget_space(dset3_id);                                   \
+    CHECK_I(space3_id, "H5Dget_space");                                   \
+    /* Verify dataspaces                                                  \
+     */                                                                   \
+    ret = H5Sget_simple_extent_dims(space1_id, out_dims, out_maxdims);    \
+    CHECK_I(ret, "H5Sget_simple_extent_dims");                            \
+    for(x=0; x<EXTEND_NDIMS; ++x) {                                       \
+        VERIFY(out_dims[x], (dims)[0][x], "H5Sget_simple_extent_dims");   \
+        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims"); \
+    }                                                                     \
+    ret = H5Sget_simple_extent_dims(space2_id, out_dims, out_maxdims);    \
+    CHECK_I(ret, "H5Sget_simple_extent_dims");                            \
+    for(x=0; x<EXTEND_NDIMS; ++x) {                                       \
+        VERIFY(out_dims[x], (dims)[1][x], "H5Sget_simple_extent_dims");   \
+        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims"); \
+    }                                                                     \
+    ret = H5Sget_simple_extent_dims(space3_id, out_dims, out_maxdims);    \
+    CHECK_I(ret, "H5Sget_simple_extent_dims");                            \
+    for(x=0; x<EXTEND_NDIMS; ++x) {                                       \
+        VERIFY(out_dims[x], (dims)[2][x], "H5Sget_simple_extent_dims");   \
+        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims"); \
+    }                                                                     \
+    /* Close dataspaces                                                   \
+     */                                                                   \
+    CHECK_I(H5Sclose(space1_id), "H5Sclose");                             \
+    CHECK_I(H5Sclose(space2_id), "H5Sclose");                             \
+    CHECK_I(H5Sclose(space3_id), "H5Sclose");                             \
+} /* define TSOHM_VDE_VERIFY_SPACES */
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ * Macro:      TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS()
+ *
+ * Purpose:    Encapsulate a common pattern
+ *             Wrapper to close and reopen file and datasets:
+ *                + "dataset" (dset_id)
+ *                + if n > 1 then include "dataset2" (dset_id2)
+ *                + if n > 2 then include "dataset3" (dset_id3)
+ *                + file (file_id)
+ *
+ * Programmer: Jacob Smith
+ *             2018 November 5
+ * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ */
+#define TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(n)               \
+{                                                              \
+    CHECK_I(H5Dclose(dset1_id), "H5Dclose");                   \
+    if ((n) > 1)                                               \
+        CHECK_I(H5Dclose(dset2_id), "H5Dclose");               \
+    if ((n) > 2)                                               \
+        CHECK_I(H5Dclose(dset3_id), "H5Dclose");               \
+    CHECK_I(H5Fclose(file_id), "H5Fclose");                    \
+                                                               \
+    file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);    \
+    CHECK_I(file_id, "H5Fopen");                               \
+    dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);      \
+    CHECK_I(dset1_id, "H5Dopen2");                             \
+    if ((n) > 1) {                                             \
+        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT); \
+        CHECK_I(dset2_id, "H5Dopen2");                         \
+    }                                                          \
+    if ((n) > 2) {                                             \
+        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT); \
+        CHECK_I(dset3_id, "H5Dopen2");                         \
+    }                                                          \
+} /* define TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS */
+
+    /* Remember the current # of reported errors */
     old_nerrs = GetTestNumErrs();
 
-    /* Create file */
     file_id = H5Fcreate(FILENAME, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT);
     CHECK_I(file_id, "H5Fcreate");
 
@@ -3257,251 +3447,49 @@ test_sohm_extend_dset_helper(hid_t fcpl_id, hbool_t close_reopen)
     CHECK_I(orig_space_id, "H5Screate_simple");
     dset1_id = H5Dcreate2(file_id, "dataset", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset1_id, "H5Dcreate2");
-
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-    }
+    if(close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(1);
 
     /* Create another dataset starting with the same dataspace */
     dset2_id = H5Dcreate2(file_id, "dataset2", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset2_id, "H5Dcreate2");
-
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(2);
 
     /* Create a third dataset with the same dataspace */
     dset3_id = H5Dcreate2(file_id, "dataset3", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset3_id, "H5Dcreate2");
-
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
     /* Extend the first dataset */
     ret = H5Dset_extent(dset1_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
-    /* Get the dataspaces from the datasets */
-    space1_id = H5Dget_space(dset1_id);
-    CHECK_I(space1_id, "H5Dget_space");
-    space2_id = H5Dget_space(dset2_id);
-    CHECK_I(space2_id, "H5Dget_space");
-    space3_id = H5Dget_space(dset3_id);
-    CHECK_I(space3_id, "H5Dget_space");
-
-    /* Verify the dataspaces */
-    ret = H5Sget_simple_extent_dims(space1_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space2_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims1[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space3_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims1[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    /* Close all three dataspaces */
-    ret = H5Sclose(space1_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space2_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space3_id);
-    CHECK_I(ret, "H5Sclose");
+    space_dims[0] = dims2;
+    space_dims[1] = dims1;
+    space_dims[2] = dims1;
+    TSOHM_VDE_VERIFY_SPACES(space_dims);
 
     /* Extend the second dataset */
     ret = H5Dset_extent(dset2_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
-
-    /* Get the dataspaces from the datasets */
-    space1_id = H5Dget_space(dset1_id);
-    CHECK_I(space1_id, "H5Dget_space");
-    space2_id = H5Dget_space(dset2_id);
-    CHECK_I(space2_id, "H5Dget_space");
-    space3_id = H5Dget_space(dset3_id);
-    CHECK_I(space3_id, "H5Dget_space");
-
-    /* Verify the dataspaces */
-    ret = H5Sget_simple_extent_dims(space1_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space2_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
+    if(close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
-    ret = H5Sget_simple_extent_dims(space3_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims1[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    /* Close all three dataspaces */
-    ret = H5Sclose(space1_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space2_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space3_id);
-    CHECK_I(ret, "H5Sclose");
+    space_dims[1] = dims2;
+    TSOHM_VDE_VERIFY_SPACES(space_dims);
 
     /* Extend the third dataset */
     ret = H5Dset_extent(dset3_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
-
-    /* Get the dataspaces from the datasets */
-    space1_id = H5Dget_space(dset1_id);
-    CHECK_I(space1_id, "H5Dget_space");
-    space2_id = H5Dget_space(dset2_id);
-    CHECK_I(space2_id, "H5Dget_space");
-    space3_id = H5Dget_space(dset3_id);
-    CHECK_I(space3_id, "H5Dget_space");
-
-    /* Verify the dataspaces */
-    ret = H5Sget_simple_extent_dims(space1_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space2_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space3_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
+    if(close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
-    /* Close all three dataspaces */
-    ret = H5Sclose(space1_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space2_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space3_id);
-    CHECK_I(ret, "H5Sclose");
+    space_dims[2] = dims2;
+    TSOHM_VDE_VERIFY_SPACES(space_dims);
 
     /* Close the datasets and file */
     ret = H5Dclose(dset1_id);
@@ -3523,164 +3511,44 @@ test_sohm_extend_dset_helper(hid_t fcpl_id, hbool_t close_reopen)
     CHECK_I(file_id, "H5Fcreate");
     dset1_id = H5Dcreate2(file_id, "dataset", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset1_id, "H5Dcreate2");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(1);
 
     /* Extend the first dataset */
     ret = H5Dset_extent(dset1_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(1);
 
     /* Create the second dataset.  Its dataspace will be unshared and then
      * become shared when extended.
      */
     dset2_id = H5Dcreate2(file_id, "dataset2", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset2_id, "H5Dcreate2");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(2);
 
     /* Extend the second dataset */
     ret = H5Dset_extent(dset2_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-    }
+    if (close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(2);
 
     /* Create the third dataset.  Its dataspace will be unshared and then
      * become shared when extended.
      */
     dset3_id = H5Dcreate2(file_id, "dataset3", H5T_NATIVE_LONG, orig_space_id, H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
     CHECK_I(dset3_id, "H5Dcreate2");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
+    if(close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
     /* Extend the third dataset */
     ret = H5Dset_extent(dset3_id, dims2);
     CHECK_I(ret, "H5Dset_extent");
-    if(close_reopen) {
-        /* If requested, close all open IDs and reopen them */
-        ret = H5Dclose(dset1_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset2_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Dclose(dset3_id);
-        CHECK_I(ret, "H5Dclose");
-        ret = H5Fclose(file_id);
-        CHECK_I(ret, "H5Fclose");
-
-        file_id = H5Fopen(FILENAME, H5F_ACC_RDWR, H5P_DEFAULT);
-        CHECK_I(file_id, "H5Fopen");
-        dset1_id = H5Dopen2(file_id, "dataset", H5P_DEFAULT);
-        CHECK_I(dset1_id, "H5Dopen2");
-        dset2_id = H5Dopen2(file_id, "dataset2", H5P_DEFAULT);
-        CHECK_I(dset2_id, "H5Dopen2");
-        dset3_id = H5Dopen2(file_id, "dataset3", H5P_DEFAULT);
-        CHECK_I(dset3_id, "H5Dopen2");
-    }
+    if(close_reopen)
+        TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS(3);
 
-    /* Get the dataspaces from the datasets */
-    space1_id = H5Dget_space(dset1_id);
-    CHECK_I(space1_id, "H5Dget_space");
-    space2_id = H5Dget_space(dset2_id);
-    CHECK_I(space2_id, "H5Dget_space");
-    space3_id = H5Dget_space(dset3_id);
-    CHECK_I(space3_id, "H5Dget_space");
-
-    /* Verify the dataspaces */
-    ret = H5Sget_simple_extent_dims(space1_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space2_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    ret = H5Sget_simple_extent_dims(space3_id, out_dims, out_maxdims);
-    CHECK_I(ret, "H5Sget_simple_extent_dims");
-    for(x=0; x<EXTEND_NDIMS; ++x) {
-        VERIFY(out_dims[x], dims2[x], "H5Sget_simple_extent_dims");
-        VERIFY(out_maxdims[x], max_dims[x], "H5Sget_simple_extent_dims");
-    }
-
-    /* Close all three dataspaces */
-    ret = H5Sclose(space1_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space2_id);
-    CHECK_I(ret, "H5Sclose");
-    ret = H5Sclose(space3_id);
-    CHECK_I(ret, "H5Sclose");
+    TSOHM_VDE_VERIFY_SPACES(space_dims);
 
     /* Close the datasets and file */
     ret = H5Dclose(dset1_id);
@@ -3698,12 +3566,15 @@ test_sohm_extend_dset_helper(hid_t fcpl_id, hbool_t close_reopen)
     ret = H5Pclose(dcpl_id);
     CHECK_I(ret, "H5Pclose");
 
-    /* Retrieve current # of errors */
+    /* Complain if this test generated errors */
     if(old_nerrs == GetTestNumErrs())
         return(0);
     else
         return(-1);
-} /* end test_sohm_extend_dset_helper() */
+/* macros are exclusive to this function */
+#undef TSOHM_VDE_CLOSE_REOPEN_FILE_AND_DSETS
+#undef TSOHM_VDE_VERIFY_SPACES
+} /* verify_dataset_extension */
 
 
 /*-------------------------------------------------------------------------
@@ -3726,74 +3597,71 @@ test_sohm_extend_dset(void)
     hid_t fcpl_id = -1;
     herr_t ret;
 
-    /* Create fcpl */
+    MESSAGE(5, ("Testing extending shared dataspaces\n"));
+
     fcpl_id = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl_id, "H5Pcreate");
-
-    /* Test extending datasets with different FCPLs */
     ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1);
     CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
 
     /* No shared messages */
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
 
     /* Only dataspaces */
     ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_SDSPACE_FLAG, 16);
     CHECK_I(ret, "H5Pset_shared_mesg_index");
 
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
     /* All messages */
-    ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1);
-    CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
     ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_SHMESG_ALL_FLAG, 16);
     CHECK_I(ret, "H5Pset_shared_mesg_index");
 
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
 
     /* All messages in lists */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 100, 50);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
 
     /* All messages in lists converted to B-trees */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 1, 0);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
 
     /* All messages in B-trees */
     ret = H5Pset_shared_mesg_phase_change(fcpl_id, 0, 0);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    ret = test_sohm_extend_dset_helper(fcpl_id, FALSE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
-    ret = test_sohm_extend_dset_helper(fcpl_id, TRUE);
-    CHECK_I(ret, "test_sohm_extend_dset_helper");
+    ret = verify_dataset_extension(fcpl_id, FALSE);
+    CHECK_I(ret, "verify_dataset_extension");
+    ret = verify_dataset_extension(fcpl_id, TRUE);
+    CHECK_I(ret, "verify_dataset_extension");
 
     ret = H5Pclose(fcpl_id);
     CHECK_I(ret, "H5Pclose");
-}
+} /* test_sohm_extend_dset */
 
 
 /*-------------------------------------------------------------------------
@@ -3827,37 +3695,31 @@ test_sohm_external_dtype(void)
     unsigned x, i;
     herr_t ret;
 
+    MESSAGE(5, ("Testing shared external datatype\n"));
+
     fcpl = H5Pcreate(H5P_FILE_CREATE);
     CHECK_I(fcpl, "H5Pcreate");
-
-    /* Set up index values for sohm */
     ret = H5Pset_shared_mesg_nindexes(fcpl, TEST_NUM_INDEXES);
     CHECK_I(ret, "H5Pset_shared_mesg_nindexes");
-
-    for(x=0; x<TEST_NUM_INDEXES; ++x)
-    {
+    for(x=0; x<TEST_NUM_INDEXES; ++x) {
         ret = H5Pset_shared_mesg_index(fcpl, x, test_type_flags[x], test_minsizes[x]);
         CHECK_I(ret, "H5Pset_shared_mesg_index");
     }
-
     ret = H5Pset_shared_mesg_phase_change(fcpl, TEST_L2B, TEST_B2L);
     CHECK_I(ret, "H5Pset_shared_mesg_phase_change");
 
-    /* Create the data space */
     space = H5Screate_simple(2, dims, NULL);
     CHECK_I(space, "H5Screate_simple");
 
-    /* Create a data type for s1_t */
     s1_tid = H5Tcreate(H5T_COMPOUND, sizeof(s1_t));
     CHECK_I(s1_tid, "H5Tcreate");
-
     ret = H5Tinsert(s1_tid, "a", HOFFSET(s1_t,a), H5T_NATIVE_INT);
     CHECK_I(ret, "H5Tinsert");
-
     ret = H5Tinsert (s1_tid, "b", HOFFSET(s1_t,b), H5T_NATIVE_INT);
     CHECK_I(ret, "H5Tinsert");
 
-    /* Create the first file for this test */
+    /* Set up dataset in first file
+     */
     file1 = H5Fcreate(FILENAME_SRC, H5F_ACC_TRUNC, fcpl, H5P_DEFAULT);
     CHECK_I(file1, "H5Fcreate");
 
@@ -3866,7 +3728,6 @@ test_sohm_external_dtype(void)
     CHECK(ret, FAIL, "H5F__get_sohm_mesg_count_test");
     VERIFY(dmsg_count, 0, "H5F__get_sohm_mesg_count_test");
 
-    /* Create data set */
     dataset1 = H5Dcreate2(file1, "dataset_1", s1_tid, space, H5P_DEFAULT, H5P_DEFAULT,
         H5P_DEFAULT);
     CHECK_I(dataset1, "H5Dcreate2");
@@ -3876,26 +3737,26 @@ test_sohm_external_dtype(void)
     CHECK(ret, FAIL, "H5F__get_sohm_mesg_count_test");
     VERIFY(dmsg_count, 1, "H5F__get_sohm_mesg_count_test");
 
-    /* Retieve the dataset's datatype */
     dset1_tid = H5Dget_type(dataset1);
     CHECK_I(dset1_tid, "H5Dget_type");
 
     /* Allocate space and initialize data */
     orig = (s1_t*)HDmalloc(NX * NY * sizeof(s1_t));
+    if (orig == NULL)
+        CHECK_I(-1, "HDmalloc");
     for(i=0; i<NX*NY; i++) {
         s_ptr = (s1_t*)orig + i;
         s_ptr->a = (int)(i * 3 + 1);
         s_ptr->b = (int)(i * 3 + 2);
     }
 
-    /* Write the data to the dataset1 */
     ret = H5Dwrite(dataset1, s1_tid, H5S_ALL, H5S_ALL, H5P_DEFAULT, orig);
     CHECK_I(ret, "H5Dwrite");
-
     ret = H5Dclose(dataset1);
     CHECK_I(ret, "H5Dclose");
 
-    /* Create the second file for this test */
+    /* Create dataset in second file using datatype from dataset in the first file
+     */
     file2 = H5Fcreate(FILENAME_DST, H5F_ACC_TRUNC, fcpl, H5P_DEFAULT);
     CHECK_I(file2, "H5Fcreate");
 
@@ -3904,7 +3765,6 @@ test_sohm_external_dtype(void)
     CHECK(ret, FAIL, "H5F__get_sohm_mesg_count_test");
     VERIFY(dmsg_count, 0, "H5F__get_sohm_mesg_count_test");
 
-    /* Create a data set using the datatype of the dataset in the first file. */
     dataset2 = H5Dcreate2(file2, "dataset_2", dset1_tid, space, H5P_DEFAULT, H5P_DEFAULT,
         H5P_DEFAULT);
     CHECK_I(dataset2, "H5Dcreate2");
@@ -3914,54 +3774,44 @@ test_sohm_external_dtype(void)
     CHECK(ret, FAIL, "H5F__get_sohm_mesg_count_test");
     VERIFY(dmsg_count, 1, "H5F__get_sohm_mesg_count_test");
 
-    /* Write the data to the dataset2 */
     ret = H5Dwrite(dataset2, s1_tid, H5S_ALL, H5S_ALL, H5P_DEFAULT, orig);
     CHECK_I(ret, "H5Dwrite");
 
+    /* Close references to the first file */
     ret = H5Dclose(dataset2);
     CHECK_I(ret, "H5Dclose");
-
-    /* Close file 1 and the dataset's datatype in file 1.  Verify that the datatype in
-     * file 2 is still accessible. */
     ret = H5Tclose(dset1_tid);
     CHECK_I(ret, "H5Tclose");
-
     ret = H5Fclose(file1);
     CHECK_I(ret, "H5Fclose");
 
-    /* Open the dataset in file 2 */
+    /* Verify that datatype details are still accessible by second file
+     */
     dataset2 = H5Dopen2(file2, "dataset_2", H5P_DEFAULT);
     CHECK_I(dataset2, "H5Dopen2");
 
-    /* Retieve the dataset's datatype */
     dset2_tid = H5Dget_type(dataset2);
     CHECK_I(dset2_tid, "H5Dget_type");
 
-    /* Verify the datatype is compound */
     dtype_class = H5Tget_class(dset2_tid);
     VERIFY(dtype_class, H5T_COMPOUND, "H5Tget_class");
 
+    /* Cleanup
+     */
     ret = H5Tclose(dset2_tid);
     CHECK_I(ret, "H5Tclose");
-
     ret = H5Dclose(dataset2);
     CHECK_I(ret, "H5Dclose");
-
-    /* Finishing test and release resources */
     ret = H5Sclose(space);
     CHECK_I(ret, "H5Sclose");
-
     ret = H5Tclose(s1_tid);
     CHECK_I(ret, "H5Tclose");
-
     ret = H5Pclose(fcpl);
     CHECK_I(ret, "H5Pclose");
-
     ret = H5Fclose(file2);
     CHECK_I(ret, "H5Fclose");
-
     HDfree(orig);
-}
+} /* test_sohm_external_dtype */
 
 
 /****************************************************************
@@ -3972,11 +3822,14 @@ test_sohm_external_dtype(void)
 void
 test_sohm(void)
 {
-    /* Output message about test being performed */
     MESSAGE(5, ("Testing Shared Object Header Messages\n"));
 
-    test_sohm_fcpl();		/* Test SOHMs and file creation plists */
+    test_sohm_fcpl();           /* Test SOHMs and file creation plists */
+    test_sohm_fcpl_errors();    /* Bogus H5P* calls for SOHMs */
     test_sohm_size1();          /* Tests the sizes of files with one SOHM */
+#if 0 /* TODO: REVEALS BUG TO BE FIXED - SEE JIRA HDFFV-10645 */
+    test_sohm_size_consistency_open_create();
+#endif /* Jira HDFFV-10645 */
     test_sohm_attrs();          /* Tests shared messages in attributes */
     test_sohm_size2(0);         /* Tests the sizes of files with multiple SOHMs */
     test_sohm_size2(1);         /* Tests the sizes of files with multiple
@@ -3989,17 +3842,17 @@ test_sohm(void)
 
     test_sohm_extend_dset();    /* Test extending shared datasets */
     test_sohm_external_dtype(); /* Test using datatype in another file */
-} /* test_sohm() */
+} /* test_sohm */
 
 
 /*-------------------------------------------------------------------------
- * Function:	cleanup_sohm
+ * Function:    cleanup_sohm
  *
- * Purpose:	Cleanup temporary test files
+ * Purpose:     Cleanup temporary test files
  *
- * Return:	none
+ * Return:      none
  *
- * Programmer:	James Laird
+ * Programmer:  James Laird
  *              October 9, 2006
  *
  * Modifications:
@@ -4012,5 +3865,5 @@ cleanup_sohm(void)
     remove(FILENAME);
     remove(FILENAME_SRC);
     remove(FILENAME_DST);
-}
+} /* cleanup_sohm */
 
diff --git a/test/vol_plugin.c b/test/vol_plugin.c
new file mode 100644
index 0000000..236a67e
--- /dev/null
+++ b/test/vol_plugin.c
@@ -0,0 +1,291 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Purpose:     Tests basic VOL plugin operations (registration, etc.).
+ *              Uses the null VOL connector (built with the testing code)
+ *              which is loaded as a dynamic plugin.
+ *
+ * TO DO:       Adapt the null VOL connector to do something interesting with
+ *              the property list.
+ */
+
+#include "h5test.h"
+
+#include "null_vol_connector.h"
+
+
+/*-------------------------------------------------------------------------
+ * Function:    test_registration_by_value()
+ *
+ * Purpose:     Tests if we can load, register, and close a VOL
+ *              connector by value.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+test_registration_by_value(void)
+{
+    htri_t  is_registered   = FAIL;
+    hid_t   vol_id          = H5I_INVALID_HID;
+
+    TESTING("VOL registration by value");
+
+    /* The null VOL connector should not be registered at the start of the test */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    /* Register the connector by value */
+    if((vol_id = H5VLregister_connector_by_value(NULL_VOL_CONNECTOR_VALUE, H5P_DEFAULT)) < 0)
+        TEST_ERROR;
+
+    /* The connector should be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(FALSE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector was not registered");
+
+    /* Unregister the connector */
+    if(H5VLunregister_connector(vol_id) < 0)
+        TEST_ERROR;
+
+    /* The connector should not be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    PASSED();
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        H5VLunregister_connector(vol_id);
+    } H5E_END_TRY;
+    return FAIL;
+
+} /* end test_registration_by_value() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    test_registration_by_name()
+ *
+ * Purpose:     Tests if we can load, register, and close a VOL
+ *              connector by name.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+test_registration_by_name(void)
+{
+    htri_t  is_registered   = FAIL;
+    hid_t   vol_id          = H5I_INVALID_HID;
+
+    TESTING("VOL registration by name");
+
+    /* The null VOL connector should not be registered at the start of the test */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    /* Register the connector by name */
+    if((vol_id = H5VLregister_connector_by_name(NULL_VOL_CONNECTOR_NAME, H5P_DEFAULT)) < 0)
+        TEST_ERROR;
+
+    /* The connector should be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(FALSE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector was not registered");
+
+    /* Unregister the connector */
+    if(H5VLunregister_connector(vol_id) < 0)
+        TEST_ERROR;
+
+    /* The connector should not be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    PASSED();
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        H5VLunregister_connector(vol_id);
+    } H5E_END_TRY;
+    return FAIL;
+
+} /* end test_registration_by_name() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    test_multiple_registration()
+ *
+ * Purpose:     Tests if we can register a VOL connector multiple times.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+#define N_REGISTRATIONS 10
+static herr_t
+test_multiple_registration(void)
+{
+    htri_t  is_registered   = FAIL;
+    hid_t   vol_ids[N_REGISTRATIONS];
+    int     i;
+
+    TESTING("registering a VOL connector multiple times");
+
+    /* The null VOL connector should not be registered at the start of the test */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    /* Register the connector multiple times */
+    for(i = 0; i < N_REGISTRATIONS; i++) {
+        if((vol_ids[i] = H5VLregister_connector_by_name(NULL_VOL_CONNECTOR_NAME, H5P_DEFAULT)) < 0)
+            TEST_ERROR;
+    }
+
+    /* The connector should be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(FALSE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector was not registered");
+
+    /* Unregister the connector */
+    for(i = 0; i < N_REGISTRATIONS; i++) {
+        if(H5VLunregister_connector(vol_ids[i]) < 0)
+            TEST_ERROR;
+        /* Also test close on some of the IDs. This call currently works
+         * identically to unregister.
+         */
+        i++;
+        if(H5VLclose(vol_ids[i]) < 0)
+            TEST_ERROR;
+    }
+
+    /* The connector should not be registered now */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    PASSED();
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        for(i = 0; i < N_REGISTRATIONS; i++)
+            H5VLunregister_connector(vol_ids[i]);
+    } H5E_END_TRY;
+    return FAIL;
+
+} /* end test_multiple_registration() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    test_getters()
+ *
+ * Purpose:     Tests H5VL getters
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+test_getters(void)
+{
+    htri_t  is_registered   = FAIL;
+    hid_t   vol_id          = H5I_INVALID_HID;
+    hid_t   vol_id_out      = H5I_INVALID_HID;
+
+    TESTING("VOL getters");
+
+    /* The null VOL connector should not be registered at the start of the test */
+    if((is_registered = H5VLis_connector_registered(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(TRUE == is_registered)
+        FAIL_PUTS_ERROR("NULL VOL connector is inappropriately registered");
+
+    /* Register the connector by name */
+    if((vol_id = H5VLregister_connector_by_name(NULL_VOL_CONNECTOR_NAME, H5P_DEFAULT)) < 0)
+        TEST_ERROR;
+
+    /* Get the connector's ID */
+    if((vol_id_out = H5VLget_connector_id(NULL_VOL_CONNECTOR_NAME)) < 0)
+        TEST_ERROR;
+    if(vol_id != vol_id_out)
+        FAIL_PUTS_ERROR("VOL connector IDs don't match");
+
+    /* Unregister the connector */
+    if(H5VLunregister_connector(vol_id) < 0)
+        TEST_ERROR;
+
+    PASSED();
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        H5VLunregister_connector(vol_id);
+    } H5E_END_TRY;
+    return FAIL;
+
+} /* end test_getters() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    main
+ *
+ * Purpose:     Tests VOL connector plugin operations
+ *
+ * Return:      EXIT_SUCCESS/EXIT_FAILURE
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+main(void)
+{
+    int nerrors = 0;
+
+    h5_reset();
+
+    HDputs("Testing VOL connector plugin functionality.");
+
+    nerrors += test_registration_by_name() < 0          ? 1 : 0;
+    nerrors += test_registration_by_value() < 0         ? 1 : 0;
+    nerrors += test_multiple_registration() < 0         ? 1 : 0;
+    nerrors += test_getters() < 0                       ? 1 : 0;
+
+    if(nerrors) {
+        HDprintf("***** %d VOL connector plugin TEST%s FAILED! *****\n",
+            nerrors, nerrors > 1 ? "S" : "");
+        HDexit(EXIT_FAILURE);
+    }
+
+    HDputs("All VOL connector plugin tests passed.");
+
+    HDexit(EXIT_SUCCESS);
+
+} /* end main() */
+
diff --git a/testpar/Makefile.am b/testpar/Makefile.am
index 7262ca6..a11099d 100644
--- a/testpar/Makefile.am
+++ b/testpar/Makefile.am
@@ -21,11 +21,19 @@ include $(top_srcdir)/config/commence.am
 
 AM_CPPFLAGS+=-I$(top_srcdir)/src -I$(top_srcdir)/test
 
+# Test scripts--
+#       testpflush.sh:
+TEST_SCRIPT_PARA = testpflush.sh
+SCRIPT_DEPEND = t_pflush1$(EXEEXT) t_pflush2$(EXEEXT) 
+
+check_SCRIPTS = $(TEST_SCRIPT_PARA)
+
 # Test programs.  These are our main targets.
 #
-TEST_PROG_PARA=t_mpi t_bigio testphdf5 t_cache t_cache_image t_pflush1 t_pflush2 t_pread t_pshutdown t_prestart t_init_term t_shapesame t_filters_parallel
+TEST_PROG_PARA=t_mpi t_bigio testphdf5 t_cache t_cache_image t_pread t_pshutdown t_prestart t_init_term t_shapesame t_filters_parallel
 
-check_PROGRAMS = $(TEST_PROG_PARA)
+# t_pflush1 and t_pflush2 are used by testpflush.sh
+check_PROGRAMS = $(TEST_PROG_PARA) t_pflush1 t_pflush2
 
 testphdf5_SOURCES=testphdf5.c t_dset.c t_file.c t_file_image.c t_mdset.c \
 	t_ph5basic.c t_coll_chunk.c t_span_tree.c t_chunk_alloc.c t_filter_read.c \
diff --git a/testpar/testpflush.sh.in b/testpar/testpflush.sh.in
new file mode 100644
index 0000000..02f0e26
--- /dev/null
+++ b/testpar/testpflush.sh.in
@@ -0,0 +1,64 @@
+#! /bin/sh
+#
+# Copyright by The HDF Group.
+# Copyright by the Board of Trustees of the University of Illinois.
+# All rights reserved.
+#
+# This file is part of HDF5.  The full HDF5 copyright notice, including
+# terms governing use, modification, and redistribution, is contained in
+# the COPYING file, which can be found at the root of the source code
+# distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.
+# If you do not have access to either file, you may request a copy from
+# help@hdfgroup.org.
+#
+#
+# Test script for the parallel flush test
+#
+# The parallel flush test uses two programs to test flush operations
+# in parallel HDF5. The first program purposely exits without calling
+# MPI_Finalize(), which is an error under the MPI standard and mpiexec
+# in some implementations will return an error code even though all
+# processes exit successfully. This script lets us swallow the error
+# from the first program.
+#
+# True errors in the first program will be detected as errors in the
+# second program, so watch out for that.
+#
+# Programmer:   Dana Robinson
+#               Fall 2018
+
+# The build (current) directory might be different than the source directory.
+if test -z "$srcdir"; then
+   srcdir=.
+fi
+
+# Turn the $$ we use to avoid Autotools munging into $
+#
+# Allowing $$ to substitute in both the RUNPARALLEL string and the
+# regexp is intentional. There doesn't seem to be a way around
+# this using quote shenanigans. The downside is that there is a remote
+# chance that the shell's pid will match a number in the RUNPARALLEL
+# variable, but that seems less likely to cause problems than expecting
+# library builders to specify two almost identical versions of the
+# RUNPARALLEL command, one for use in scripts and one via Makefiles.
+RUNPARALLELSCRIPT=`echo "@RUNPARALLEL@" | sed "s/$$/\$/g"`
+
+# ==========================================
+# Run the first parallel flush test program
+# (note that we ignore any errors here)
+# ==========================================
+echo "*** NOTE ***********************************************************"
+echo "You may see complaints from mpiexec et al. that not all processes"
+echo "called MPI_Finalize(). This is an intended characteristic of the"
+echo "test and should not be considered an  error."
+echo "********************************************************************"
+eval ${RUNPARALLELSCRIPT} ./t_pflush1
+
+
+# ===========================================
+# Run the second parallel flush test program
+# The return code of this call is the return
+# code of the script.
+# ===========================================
+eval ${RUNPARALLELSCRIPT} ./t_pflush2
+
diff --git a/tools/test/h5jam/tellub.c b/tools/test/h5jam/tellub.c
index aa779b3..559c677 100644
--- a/tools/test/h5jam/tellub.c
+++ b/tools/test/h5jam/tellub.c
@@ -53,7 +53,7 @@ usage (const char *prog)
 /*-------------------------------------------------------------------------
  * Function:    parse_command_line
  *
- * Purpose:     Parse the command line for the h5dumper.
+ * Purpose:     Parse the command line.
  *
  * Return:      Success:    void
  *              Failure:    Exits program with EXIT_FAILURE value.
@@ -89,7 +89,7 @@ parse_command_line (int argc, const char *argv[])
 /*-------------------------------------------------------------------------
  * Function:    main
  *
- * Purpose:     HDF5 user block unjammer
+ * Purpose:     HDF5 user block tell size
  *
  * Return:      EXIT_SUCCESS/EXIT_FAILURE
  *-------------------------------------------------------------------------