Transparency maps make parts of the figure, clothing, or whatever invisible. For example, if you paint the bottom of a dress black and apply it as a transparency map (as Ghost and JKeller explained), what you have painted black will disappear (in this case, the dress would appear shorter). If you paint a figure's arm black and apply that as a transmap, his arm will vanish. To better understand what we mean, download any clothing texture that contains a texture and a transparency map. The maps (layout) will be the same, but the transparency map will only be black and white. Everything black will be hidden when you render and everything white will appear. Hope that helps a little, if not let me know. :) Take care! SnowS Hoping his pictures are worth 1001 words.

my DeviantArt page: http://snowsultan.deviantart.com/

 

I do not speak as a representative of DAZ, I speak only as a long-time member here. Be nice (and quit lying about DAZ) and I'll be nice too.