/EXPORT_SYMBOLS=(OPTIONS_FILE=<name>
    [,EXCLUDE=<list of images>]
    [,export_option]
    [,NOTEMPLATES]) (I64 only)

    Creating OpenVMS shareable images that contain C++ code has long
    been a problem for users. When building a shareable image, you
    must specify a list of exported global symbols. For C++ code,
    determining this list can be very difficult for the following
    reasons:

    o  Required C++ name mangling makes it difficult to know the name
       of the external symbol created for a C++ name.

    o  OpenVMS CRC encoding (to 31 characters) further complicates
       mapping source names to object names.

    o  Certain C++ constructs require compiler-generated names to be
       created and exported.

    To help solve the problem, the HP C++ compiler provides the
    /EXPORT_SYMBOLS qualifier and __declspec(dllexport) declaration
    modifier.

    The default file extension for the OPTIONS_FILE <name> is .OPT.

    If the file exists, the compiler appends to it. If the file does
    not exist, the compiler creates it.

    The output for the compilation is:

          !
          ! Entries added for <module>
          !
          <symbol vector>
          <symbol vector>
          .
          .
          .

    The output file is suitable input to a linker options file that
    can be used to build a shareable image containing the compiled
    object.

    The format of each <symbol vector> is:

       SYMBOL_VECTOR=(<global name>={DATA | PROCEDURE}) ! <comment field>

    The <comment field> format is:

       <unmangled name> [<promoted static flag>] [<class information>]

    The <promoted static flag> is one of the following:

       *PSDM* - for promoted static data members
       *PTSDM* - for promoted template static data members

    The <promoted static flag> is output whenever the symbol is a
    promoted local static or a promoted template static data member.
    This is important because these variables, while declared static,
    actually become global symbols when compiled.

    The <class information> field is present if the symbol is a
    member of a class. It contains the name of the class.

                                  NOTES

       o  When /EXPORT_SYMBOLS is specified, an object file must
          also be generated. So /EXPORT_SYMBOLS cannot be used with
          /NOOBJ, /PREPROCESS_ONLY, or any other qualifier that
          prevents the creation of an object file.

       o  When the options file already exists, the compiler reads
          all the symbols that are listed there. If the current
          compilation also defines one of those symbols, that
          symbol will not be added to the options file. This is
          necessary to prevent SYMVALRDEF warnings from the linker.

       o  When the compiler reads the existing file, it treats
          SYMBOL_VECTOR directives that are in comments (of the
          form !SYMBOL_VECTOR...) as if they were not commented.
          In this way, if a user does not want to export a symbol,
          placing it in comments will prevent the compiler from
          emitting a directive for that symbol when it compiles
          other sources that might also define the symbol.

       o  The symbols placed in the options file are a subset
          of the symbols defined in the output object file. The
          export_option value controls exactly which symbols are
          placed there. There are three choices:

          Export_
          option
          Value     Usage

          ALL       Place all symbols suitable for placement in
                    a sharable image into the options file. The
                    compiler knows that certain symbols are not
                    suited for placement in a shareable image
                    and excludes them from the options file.
                    Some examples are certain compiler-generated
                    constructor/destructor jackets and symbols in
                    the unnamed namespace.
          EXPLICIT  Place only those symbols marked with the
                    __declspec(dllexport) declaration modifier
                    into the options file.
          AUTOMATIC(If the compiler processes a
                    __declspec(dllexport), then act as if EXPLICIT
                    was specified. If the compiler does not
                    process a __declspec(dllexport), then act
                    as if ALL was specified.

       o  The EXCLUDE option of the /EXPORT_SYMBOLS qualifier
          can be used to specify a list of shareable images. The
          compiler searches these images for any symbols that it
          might want to place in the output options file. If it
          finds the symbol in the image, then that symbol will not
          be put into the options file.

       o  The NOTEMPLATES option can be used to control
          the emission of symbols associated with template
          instantiations. Specifying this option causes the
          compiler to suppress symbols created by template
          instantiation. This includes instantiations of class
          templates, its data members and member functions, and
          instantiations of function templates. This option could
          be used to avoid multiple definition diagnostics from the
          linker if multiple sharable images might be instantiating
          (and exporting) the same template symbols. Symbols
          marked with __declspec(dllexport) still get exported.
          This option has no effect on symbols from template
          specializations. Note that while this option might
          make the sharable images smaller by not exporting the
          template symbols, the executable image that links with
          these sharable images might be larger because it will
          contain the instantiated template symbols.

    Because shareable images almost always contain a number of
    objects, the commands for creating the options file the first
    time might be:

    $ DELETE options_file.OPT;*
    $ CXX SOURCE1/EXPORT_SYMBOLS=OPTIONS_FILE=options_file
    $ CXX SOURCE2/EXPORT_SYMBOLS=OPTIONS_FILE=options_file
    $ CXX SOURCE3/EXPORT_SYMBOLS=OPTIONS_FILE=options_file
       .
       .
       .
    $ CXX SOURCEn/EXPORT_SYMBOLS=OPTIONS_FILE=options_file

    Where SOURCE1 - SOURCEn are the sources for the shareable. After
    the compilations, the options_file.OPT will contain correct
    symbol vector information for the shareable.

    The first time this options file is created, it can be considered
    a candidate options file. It contains all the symbol vector
    entries for all the C++ globals that make sense to export from
    the C++ language point of view. A user can then edit this file to
    exclude (by commenting out) entries that should not be exported,
    based on the design of the library.

    Once an options file is created, it should be maintained for
    input to subsequent compilations. In this way, any new symbols
    caused by a change in the source will be added to the end of the
    compilation. Any existing symbols will not be added, as described
    in the NOTES section above. This technique ensures that the order
    of symbols remains unchanged, and that future shared libraries
    are compatible with existing ones.