nontrans trans - Two values: the first is used by all non-transparent shadowfaces, the second by all TRANS33 or TRANS66 shadowfaces.
By default, non-transparent faces cast black shadows, and transparent faces project their textures. Use the following values to set the indicated shadow styles:
1 - Black shadows.
2 - Single-color shadows (uses reflectivity color).
3 - Projects the face's texture.
The TRANS33 surface property makes shadows 33% opaque, while TRANS66 makes them 66%. If the texture has an alpha mask, it will always be projected with the shadow. Alpha depends on the texture format: .TGA & .M32 use their alpha channel, .WAL & .PCX make the last palette color fully transparent.
The original Quake2.exe only renders .WAL palette transparency on TRANS* faces. Several engine-mods offer a workaround: setting both TRANS33 & TRANS66 will render the face fully opaque, but also with palette transparency. ArghRad supports this feature by treating that combination as non-transparent.