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

 Message        <Context> "<expression1>" and "<expression2>" cannot
                be compared for equality or inequality.

 Description    Because of their types, the two expressions cannot be
                compared for equality or inequality.  The rules for
                which types can be compared are rather complicated
                and differ based upon the compiler mode.  Refer to
                the language documentation for a complete list of
                valid combinations.

 User Action    Modify the comparison to use valid types.  This can
                often be done by casting one of the expressions to
                the type of the other.