In the mesh there aren't skeleton, only bone name and the vertices percentage of assignment, so is impossible know the position and relationship about bones. This data are stored in the cas file, in fact at the start and end of file there are the relationship and local positions, also Knight Errant use a skelexport files to store this type of data.
In max, with my script, where aren't relations about skeleton and skin modifier. When you export a mesh the script read only all bone in the scene, and read the skin modifier, DONT BUILD THE SKELETON, in fact if you use "Use Skeleton" or not is the same thing.
The skeleton are use ONLY TO BUILD CORRECTLY animations.
When importing a mesh the script import only bone name but if you utilize the options "Use Skeleton" it try to build also skeleton, but isn't necessary for mesh files, it's only a useful option to work more correct when editing animations.