XMF (Extensible Music Format) is a tree-based digital container format used to bundle music-oriented content, such as a MIDI file and optionally the sounds it uses, liner notes or other content grouped by language-codes. There are currently five XMF File Types defined. The latest of which is XMF File Type 4 (counted from zero) and is called Interactive XMF (iXMF). The specifications for the XMF were first published in 2001 by the MMA.