Incidently, hobo signs are not that much different from Thief's magic Glyphs. I am going to guess that modifying a bump-map into an alternate would suffice for an etching along an otherwise common texture. I dunno about anything else technically. It might be possible to have decals which only show up when specific lights are active...ie Wall in shadow due to boxes, which are illuminated with moonlight; move boxes message revealed which does not show up under lamp/candle/torch light. Oh look hidden blood-spill shows up under blacklights. I will investigate, and will stop posting demanding nonsense.