I found this at a description for a V4 product:
10 full character MORs
1 reset MOR
1 Main texture MAT
1 Tattoo partial MAT
3 Eye partial MATs
4 Makeup partial MATs:
I dont know what MOR means or what it is good for.
MOR is an unofficial abbreviation for Morph File. A MAT applies the textures. A MOR applies the morphs. There’s no real standardization for what’s in the file. It could:
Set the values of preset morphs.
Inject new morphs and set their values
Contain entirely new deformations
Any combination of the above.
There’s also no standardization of the use of the term. Some people call them MORs, others don’t. Sometimes they’re the same as INJ files.