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

.SUFFIXES Pseudotarget

Syntax: .SUFFIXES : extensions...

This pseudotarget defines file extensions to try when NMAKE needs to build a target file for which no dependents are specified. NMAKE searches the current directory for a file with the same name as the target file and an extension in <extensions...>. If NMAKE finds such a file, and if an inference rule applies to the file, NMAKE treats the file as a dependent of the target.

The .SUFFIXES pseudotarget is predefined as

.SUFFIXES : .obj .exe .c .asm

To add extensions to the list, specify .SUFFIXES : followed by the new extensions. For example, the following would enable you to write interence rules for PL/I source files.

.SUFFIXES: .pli

To clear the list, specify

.SUFFIXES:

Only those extensions specified in .SUFFIXES can have inference rules. NMAKE ignores inference rules unless the extensions have been specified in a .SUFFIXES list.

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