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

 Message        Macro redefined.

 Description    A #define preprocessing directive has redefined a
                macro whose previous definition contained an error or
                warning.  Normally, the compiler will issue a warning
                if a macro is redefined to something other than the
                previous definition.  However, if the previous
                definition caused a warning or error to be generated,
                this informational message is output instead.

 User Action    Do not redefine a macro without first undefining it.