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

 Message        <Context> relaxed struct or union type compatibility
                is a language extension.

 Description    In certain modes, the compiler will allow assignments
                or comparisons between structs or unions of different
                types if their sizes are the same.  This is an
                extension to standard C.  Other C compilers might not
                successfully compile a program that uses this
                extension.

 User Action    Recode the operation to use one of the memxxx
                run-time library functions.