High Quality Content by WIKIPEDIA articles! Music Markup Language (MML) is an XML application to describe music objects and events, using different modules and markup. MML can be delivered in different formats, such as text, block bars or piano roll, Common Western Notation or MIDI-devices. Since MML can be employed in such simple and accessible formats, it`s possible to sequence music without resorting to expensive software. MML compositions can, for instance, be rendered via a simple Java plug-in.