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

Directives example

!INCLUDE <infrules.txt>
!CMDSWITCHES +D
winner.exe:winner.obj
!IFDEF DEBUG
! IF "$(DEBUG)"=="y"
     ilink /de winner.obj;
! ELSE
     ilink winner.obj;
! ENDIF
!ELSE
! ERROR Macro named DEBUG is not defined.
!ENDIF

The directives in this example do the following:

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