Look at those textures to either side closely and you'll see that they actually have a stipple pattern in them, with palette entry 255 alternating with the regular texture pattern.
Now turn r_drawentities off and you'll see lots of little particle effects going on behind them; these things were clearly meant to be seen through, but unfortunately (or perhaps fortunately) they never worked, not even in software Quake.
Is it worth supporting these properly in an engine I wonder? If a hack never even worked properly to begin with, is it a feature that must be fixed?
