I have a pk3 file named "hud_magc.pk3"
"/" contains:
"ui" - folder
"magc_hud.cfg" - a file you can execute in game to set the hud. It is the exact same thing as typing '/cg_hudfiles ui/magc_hud.cfg' in the console.
"readme.txt" - a redundant readme file
"/ui/" contains:
"assets" - folder
"magc_alien_hud_general.cfg" - general alien hud menuDef file
"magc_hud.cfg" - contents found in my above post on January 30, 2008, 07:04:25 PM
"magc_human_hud.cfg" - human hud menuDef file
"/ui/assets/" contains:
"human" - folder
"/ui/assets/human/" contains:
"magc.tga" - a static test image (works)
"stamina.tga" - a replacement for the existing stamina images (works)
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I don't know too much about how the pk3's get included in the game as far as their scope. From observation, I assume that when loaded, data from one pk3 can see data inside another pk3 that is loaded in the game, as well as see the resources in the data-1.1.0.pk3.