Added this bit about tattoos from the Ray of Matar Chronicle:
Parts of the face are reserved for the clan tattoos and the shoulders are reserved for the rank tattoos, which show the occupation and status of the person
, a sentence about war tattoos, and this clarification / FAQ about voluval marks:
There are no official reference catalogues OOC for the Marks, so for roleplay purposes you basically get to invent your own: a physical description of the. mark, its name, and what it means to the local clan/tribe is what you need.