These are just images, not yet made in Quake 2 .wal format. The images have a transparent color, which in Quake 2 DoD will translate as being holes in signs, like in a cast iron stencil. Every medieval game may have signs as to know what type of building you are in. Simple as may look, they deliver a message.
Here you see a Dawn of Darkness ingame .wal 256 color texture and a .png image comparison. I have made the texture first with
Wood Workshop, in conjunction with Paint Shop Pro 7 and Wally. Below is the link to the program.