Three-dimensional materials file created in the Cal3D binary materials format; stores references to the graphics that are overlaid on 3D meshes to provide the model's surface appearance; also stores ambient, diffuse, specular, and shininess lighting properties.
CRF files are the binary version of .XRF format, which stores the material references and properties in an XML format.
You can open CRF files with several different programs in Windows, which includes Cal3dViewer and Cal3d2ogre.
You can also use Short Fuze Limited Moviestorm to open CRF files but the program only supports Windows XP, Vista, 7, and 8 and macOS Tiger, Leopard, Snow Leopard, and Lion.
NOTE: Cal3D is an open source 3D character animation library written in C++.