For those of you that are fairly new to modding CF ID is Cyber Face ID #. This is the ID number assigned to a player's appearance (skin textures and 3D model) in game.
An example is Lebron's CF ID is 1013. That means we can manipulate and mod (modify) files face1013.iff and png1013.iff to change lebron's look. There may also be more files associated with a players CF ID like the hair and facial hair files.
2K's art team has quietly done some nice work with the file structure of art assets
I have noticed that players can have multiple facial textures, I think this can be assigned through the appearance_info.RDAT file.
Example is CF ID 7855 is used for a set of twins (Cody and Caleb Martin - both on the Hornets) .
Here are all the face.iff assigned to 7855
Face file #1 - face7855.iff
Face file #2 - face7855_facialhair_ponytail.iff
Face file #3 - face7855_hair_ponytail.iff
same thing with Marquese Chris - CF ID is 7210
Face file #1 - face7210.iff
Face file #2 - face7210_facialhair_01.iff
Face file #3 - face7210_hair_braids.iff
EDIT:
This means we can assign multiple looks to a player using the same CF ID.
If you have ever noticed that sometimes players have different looks with a headband and without (DLo Russell) or has a haircut in edit player but braids in game (Russell Westbrook at beginning of the year.
This would be great for retro rosters and draft classes if we can figure this out.