Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide

Suppress messages (/C)

Syntax:/C

This option suppresses display of the NMAKE sign-on banner, nonfatal error messages, and warning messages. To suppress the sign-on banner without suppressing other messages, use the /NOLOGO option.

Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide