An XAF file is most commonly an XML-based animation format used in 3D workflows, often as a 3ds Max or Cal3D XML animation file, and its role is to store motion data rather than full characters or scenes, so opening it in a text editor like Notepad shows structured tags and numbers that define keyframes, timing, and bone transforms without actually "playing," meaning it holds the choreography of animation tracks but does not include meshes, textures, materials, lights, or cameras and assumes a compatible rig already exists.

"Opening" an XAF file most often requires importing it into the correct 3D workflow—such as bringing it into Autodesk 3ds Max through its animation tools or loading it into a Cal3D-compatible pipeline—and mismatches in bone names, hierarchy, or proportions can cause the motion to fail, appear twisted, or shift incorrectly, so checking the file in a text editor for hints like "Cal3D" or references to 3ds Max/Biped/CAT helps identify which software should import it and what matching rig you’ll need.

An XAF file centers on animation data rather than complete character assets, typically holding timelines, keyframes, and tracks that drive bone rotations or other transforms tied to specific bone names or IDs, often with interpolation curves for smooth motion, and depending on the pipeline it may store one animation or many while always defining skeletal movement over time.

An XAF file usually omits everything required to display a finished animation, offering no geometry, materials, textures, lights, or cameras and often not providing a full rig definition, instead assuming you already have the proper skeleton loaded, so by itself it’s just choreography without a performer, and importing it onto mismatched rigs—those with different bone names, structures, orientations, or proportions—can break the animation or distort it with twists and offsets.

To determine the XAF’s origin, the fastest move is to inspect it like a clue file by opening it in Notepad or Notepad++ and checking whether it’s readable XML, because structured tags imply an XML animation format while random symbols may be binary, and if readable, scanning the header or using Ctrl+F for Max, Biped, CAT, Autodesk, or familiar bone names can highlight a 3ds Max–style animation pipeline.

If the file contains "Cal3D" markers or XML attributes that look like Cal3D animation tracks, it’s probably a Cal3D-format XML expecting the correct skeleton/mesh pair, while detailed per-bone transform data and rig-style identifiers are more typical of 3ds Max workflows, and a compact game-oriented clip layout leans toward Cal3D, with surrounding files offering hints and the header lines giving the clearest indication of the exporter.