There is only one file type that uses the .XMM extension:
3ds Max XML Animation Map File
XML file used by 3ds Max, a three-dimensional animation and modeling program; defines how the loaded animation data from an .XAF file is assigned to objects in a scene; allows motion data to be merged into a 3D scene.
|Autodesk 3ds Max||Commercial|
Updated: May 15, 2011