The HTR (Hierarchical Translation Rotation) file type was developed by the Motion Analysis Corporation as the native format for its skeleton generating software. Motion Analysis is one of the industry leaders when it comes to manufacturing optical instrumentation systems and 3D optical motion capture hardware and software.

The HTR File format contains everything necessary for effective motion capture and also comes with excellent data type flexibility and a thorough basis pose specification that includes starting points for both rotation and translation.

HTR files are well structured and contain multiple sections such as header, hierarchy and segment names, base position and motion sections. They're structured in this exact same order and are identified by keywords placed in square brackets. HTR files also offer support for comments which are marked with the number sign "#" and can be placed anywhere in the line, not just at the beginning.