VMS Help CC, Messages, QUESTCOMPARE2  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        <Context> the unsigned expression "<expr>" is being
                tested to see if it is greater than zero.  This might
                not be what you intended.

 Description    An ordered comparison between an unsigned value and a
                constant that is zero may indicate a programming
                error.  Often C programmers do not realize that an
                expression has an unsigned type.  If the code is
                correct, the comparison could be more clearly coded
                by testing for equality with zero.

 User Action    Cast (or otherwise rewrite) one of the operands of
                the compare to match the signedness of the other
                operand, or compare for equality with zero.