What's with “#ifdef _MAC” in Windows header files?

Question

I was browsing through Windows\'s Platform SDK header files (what a life, right?), and I noticed many places contained references to the preprocessor symbol _MAC. F

Answer 1

I assume it is/was used for compiling Microsoft software (Office, IE, Windows Media Player) for MacOS. I know that IE and WMP for Solaris included a subset of Windows itself (e.g. libwinnt.so, libkernel32.so) as a direct replacement for the corresponding Windows DLLs.