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

 Message        Invalid optimization level <number>, defaulted to
                <number>.

 Description    An optimization level that is outside the range of
                valid optimization levels has been specified.  The
                compiler will default to the stated level.

 User Action    Supply a valid optimization level on the command
                line.