The __W macro is needed because the token-pasting operator binds to the macro's argument immediately;  Having WCHAR(y) expand to __W(y) means that __W is passed WCHAR's argument after it's been macro-expanded.  Without the intermediate step, WCHAR(VERSION) becomes LVERSION.

As for the name - I have no objection to reasonable name changes.  I picked WCHAR because it converts its argument to a wchar_t *.

Finally - I am aware that the HP/UX C compiler is broken.  Unfortunately, I am required to work with it, and can neither replace it nor ignore it.