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).
The Mobile DLS Specification defines a wavetable instrument representation format optimized for use in mobile applications. Mobile DLS is intended for use with Mobile XMF file for a complete musical performance.
The Scalable Polyphony MIDI Specification defines how to produce content that plays back according to the available polyphony of the playback device. It was conceived as a solution for "3G" mobile applications and systems.