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

 Message        <Context> "<name>" is not constant, but occurs in a
                context that requires a constant expression.

 Description    An expression that must evaluate to a compile-time is
                not a constant.

 User Action    Modify the constant expression so that it will
                evaluate as a compile-time constant.