VMS Help CC, Messages, MACROREDEF  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        The redefinition of the macro "<name>" conflicts with
                a current definition because <reason>.  The
                redefinition is now in effect.

 Description    A macro has been redefined with either different
                formal parameters and/or a different body than a
                previous definition of the macro.

 User Action    Either make all definitions of the same macro
                identical, or undefine the macro using the #undef
                preprocessing directive before it is redefined.