Syntax: .SUFFIXES : extensions...
This pseudotarget defines file extensions to try when NMAKE needs to build a target file for which no dependent files 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. To clear the list, specify
.SUFFIXES:
Note: Only those extensions specified in .SUFFIXES can have inference rules. NMAKE ignores inference rules unless the extensions have been specified in a .SUFFIXES list.