i know that cob files refer to nx3 files, so maybe a cob file describe an entity like a human character and his skeletal animation where bones meshes are in nx3 files, also in obj.tml in cob_version_12 or something like this there is information about the sex, id, animation, shadow, lighting (not sure) so it might be a format used to describe animated bodies.
cob object files has sex, id, and some other information so i think either it's a format to represent human or animals
naf files contain DIFKNIBK
nx3 files contain BTRF
cob files contain BTRF (some cob files contain DIFKNIBK)
cob BTRF files contain reference to nx3, naf and dds files and DIFKNIBK contain reference to spt files
naf seems to contain animation information as their names are like xxx_attack_xxx.naf, xxxx_cast_xxx.naf ....
nx3 files contain reference to (not always) tga/dds files, UV texture coords, particules info
i think that cob DIFKNIBK are old files as they have reference to spt files which seems to be old rappler creer files and BTRF may be an description of an object which has bones, mesh, animation info, textures
naf are skeletal animation information and nx3 would be mesh or 3d entity (might be a mesh or particules)
tml have references but not exactly what we wanted
ive thinked on truespace too monts ago..but in the end was a closed road.. a freware is a limited one...so i doubt they used it....
im sure they used entirerly xsi in production of model/animation even paint (probably for new hairdie used zbrush..just a think)