G'day
The only place I see xicht_a.paa is in the wounds section but if you look closer you'll see that every face is listed so I guess the game has certain defaults it uses or whatever. Anyway,I believe faces are defined in the description.ext file
face="face 1" (which is xicht_a.paa btw)
Look under CfgFaces in the config.cpp for more
hope this helps
L8R