"Do you mean win32?"
Nope. All my windows apps were written for the 16-bit version of Windows. That they still run perfectly in XP, but were written for Windows 3.1 is amazing to me. There's no reason that XP should be expected to run 16-bit Windows software, but it does, and perfectly.
My software makes many calls to old .dll libraries. It also does stuff that is completely different in XP, such as font installation and getting font information. Yet, .dlls I wrote to do font stuff still work just fine.
It's amazing. And it's another example of why the XP source code is going to be virtually impossible to decipher for anyone not intimately involved in its creation.
Doesn't that also make the transition to the legendary Longhorn unlikely? Except for cosmetic touches?