Every ANI file consists of an array, used for making in-game animation.
HSTA-0.ANI is an array of frame index. So the first frame of the 5th animation is given by _indexes[5]. Then the others frames are given in the HFRA-0.ANI array. Single elements of frames are given by HELE-0.ANI.
All ANI files have different formats - elements of the arrays they store are different in every file. Anyway all of them were reworked and are fully explained in libSyndicate.
Reworked ANI files: data\hele-0.ani data\hfra-0.ani data\hsta-0.ani