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

 Message        <Context> this argument to <function name> contains a
                bad conversion specification "<incorrect conversion>"
                that will cause unpredictable behavior.

 Description    The compiler has detected an illformed conversion
                specification (flags, width, precision, length
                modifier) or an unknown conversion specifier (not
                diouxefgcspn...) that will cause unpredictable
                behavior.  This might not have been what you
                intended.

 User Action    Review the documentation for this function and modify
                the conversion specification as appropriate.