ANI
Not to be confused with AIN.
ANI is an optional file format that stores animation data for models. It is only created during compilation if $animblocksize
is set.
Internally, it begins with a normal MDL 408-byte header, but zeroed out only having its length field set, and the id is IDAG instead of IDST. The header is then immediately followed by the animation block data.
The block data is indexed into from the associated .mdl file. (mstudioanimblock_t, numanimblocks, animblockindex)