This TEXTURES entry is scaled by 2 (making it 2x smaller in the game world) and is being used on the midtexture of a 64-unit-long linedef. The front side of the linedef is completely ordinary, but I gave the backside's midtexture a scale of -1 so that it would appear flipped on the other side. This line is manipulated via ACS to scroll rightwards upon activation and then after a delay, stops the scrolling and adjusts the texture x offset to the x offset it had when it stopped scrolling.
Curiously, the effect the scale has on the back side's scroll direction is desireable. It scrolls left on the back side instead, most likely due to its back midtexture having a scale of -1. However, this behavior is only present in the Doom Software renderer. The SoftPoly renderer scrolls at twice the speed (and the door jamb textures are misaligned among other things) and the OpenGL renderer exhibits some oddities too. I'll let these videos speak for themselves:
Doom Software renderer (intended behavior)
SoftPoly renderer
OpenGL renderer
For personal reasons, I'd rather not publicly release the archive as it is but I can easily PM someone with the .pk3 so that they may test it themselves.
