The angle representation for Dof


I’m confused about the angle representation for DoF’s position. From most of the documents, for a revolute joint, the angle representation might likely be euler angle if we define the joint frame along the coordinate. For a revolute joint with 3 Dof, namely spherical/ball joint, Isaac gym seems directly take the exp_map(sometime name rotvec or axis angle) rather than the ‘xyz’ euler angle. While in most situations, this two representations of the same angle are different by value.

So I wonder how Isaac gym work on this? Does it recognize the spherical joint with 3Dof and use another representation automatically? Or it has other logics?