/sys$common/syshlp/helplib.hlb CC, Messages, BADDCL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        The name "<name>" cannot be undefined.

 Description    The code has tried to #undef a macro that is
                predefined by the C standard.  This is not allowed.
                The #undef will be ignored.

 User Action    Remove the #undef directive.