The XMF Specification defines a file format containing one or more other files – such as Standard MIDI Files, Downloadable Sound (DLS) instrument files, WAV files, or other digital audio files, etc. – to create a collection of all the resources needed to present a musical piece.

Mobile XMF (XMF Type 2) is an audio format that bundles a Scalable-Polyphony MIDI (SP-MIDI) file, custom instrument samples (Mobile DLS), and copyright information all in one deliverable package (designed for mobile phones).