Tremulous supports a limited number of File Extensions (Or Formats)
Images; JPEG (.jpg), TARGA (.tga)
Audio; WAVE (.wav)
Maps; BSP (.bsp)
Models; MD3 (.md3)
Scripts; Arena (.arena), Shader (.shader), Particle (.particle), Trail (.trail), Menu (.menu), Config (.cfg)
Other; QVM (.qvm), Pk3 (.pk3)