Declaring Win32 stuff for Bmax?

Ok, thanks, so it works with @12 appended, but why do I need that, what is it, and where do I find it for other functions I need?

Also why does GetWindowThreadProcessId work perfectly without the need for the @8 but GetClassName doesn't work without the @12?

Pub.Win32 doesn't contain much of what I need, and Birdie's TWin32 mod is no longer distributed in the samples, it would seem.