ASE Rotation Animation

I had found out how 3ds max exports rotation animation in ASE file. In spite of translations are described the coordinate from original position, but rotations are described the angle as difference from last frame. I found that during I made a lot of simple examples of animation. Other trick is that frames are interpolated as spline curve, and each delta are slight different. So it's very hard to find out the parameters are delta. Anyway, I found another documentation about ASE file in http://cs.felk.cvut.cz/~sporkaa/doc/3dsnd/thesis.pdf.