Support for Quake-Style Luma Textures
This type of texture can be found in the original Quake maps—they are the luminescent areas of the texture. This trick owes its existence to the specifics of Quake’s palette, so the engine enables it only for those textures whose palette is identical to Quake or Quake 2. This palette is preserved well when textures are converted from WAD2 to WAD3; an example can be found in the "qstyle" map by Scrama.