Message        Identifier "<id>" is reserved by the
                <C89|C99|C2010...> standard and will be mapped to
                "<name>" although it is not available in the CRTL
                available to the compiler.

 Description    The specified identifier is reserved for use as an
                identifer with external lingage in the specified
                version of the C standard.  But according to the CRTL
                mapping table available to the compiler, that
                identifier is not defined in the CRTL you expect to
                link against.  This may be because the function or
                object is not yet implemented in the current
                DECC$SHR, or because you have used logical
                DECC$CRTLMAP to specify a CRTL mapping table for a
                version of the CRTL that does not implement it.

 User Action    If you intended to use the identifier as defined by
                the C standard, and you have not defined the logical
                DECC$CRTLMAP, then the identifier is not defined in
                the DECC$SHR available to the compiler.  If this is
                the latest released DECC$SHR, then the identifier is
                not yet implemented and you need to consider
                workarounds; otherwise you should upgrade to the
                latest available CRTL that does implement it.  If you
                did not intend to use the identifier as defined by
                the C standard (i.e.  it is an identifier you
                expected to be defined by your application), then you
                have a name clash with the specified version of the
                standard and you should change the spelling of the
                identifier; alternatively, you could disable
                prefixing for it using /PREFIX=EXCEPT=, or specify an
                older version of the standard with either /PREFIX= or
                /STANDARD=.