VMS Help CC, Messages, ARGLISGTR255  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        <Context> the function call specifies an argument
                list whose length exceeds maximum specified by the
                calling standard.  Any use of va_count by the called
                function will be wrong.

 Description    The OpenVMS calling standard uses a byte-sized field
                to specify the size of the argument list.  The
                argument list to this function call requires more
                storage than can be represented in this size.  As a
                result, any use of va_count in the called function
                will return inaccurate information.

 User Action    Either reduce the size of the argument list, or do
                not use va_count in the called function.