Convert a sub-make file to make file?

I need to convert sub-make files into make-files, namely Windows C# sub-make files.

The sub-make files look like:

include Windows.def 

solution = someSolution.sln

Can I just save the sub-make file as ".make?" I apologize if I'm vague, but I've googled the subject and don't have much information.

Thanks

I assume you are talking about "nmake" makefiles? I imagine you must first modify it to use an exclamation point preceding the include statement:

!include Windows.def