https://bugs.winehq.org/show_bug.cgi?id=42162
--- Comment #8 from Christian Costa titan.costa@gmail.com --- (In reply to winetest from comment #7)
But is it still used and if its for what? And is it publicly documented?
It's hard to development anything without clear instructions.
Only very old games use it. There are some resources at http://www.falconfly.de/reference.htm. The spec is at www.falconfly.de/downloads/3dfx-glide-programming-guide-rel018.zip