A communiqué from Leo Montgomery describes current development of 4ML for music representation: "4ML is an XML-compliant Music and Lyrics Markup Language; development is supported on the SourceForge forum 'fourml', which provides a collection of example applications using the 4ML language." The design goal is to create "a single, flexible, platform-independant way to describe music and lyrics that can be used by musicians and programmers alike." 4ML is formally specified in an XML DTD. The developers envision a range of applications that might make use of music encoded in 4ML, for example: "(1) A song could be written on a standard musical staff; (2) The lyrics to a song, with accompanying simplified guitar chords, could be the output; (3) The song could be played over a speaker; (4) A MIDI file could be produced; (5) A song could be written as guitar tablature; (6) The lyrics could be shown on the screen, with a kareoke-syle bouncing ball." The developers welcome reviewer feedback on this XML application.

Notation: "4ML can be written in a verbose, XML (HTML-like) style or a compact style. Many combinations of the two styles are possible. You can view 'Mary Had A Little Lamb' in verbose (XML) style or curt style. Verbose refers to writing 4ML as XML and is the recommended format for compatibility with XML browsers that are not specifically meant as mullers. Curt form may be easier for some people to write quickly, and yields a smaller file; as such, it takes less disk space and is faster to transfer. These are the same language, but curt is a sort of shorthand. For example, in verbose form, the way to play a D in octave 2, you would use this XML-style tag: <NOTE pitch="D:2" />... Currently [2001-03] it is not possible to play outside the eight-toned even-tempered scale of the Western Tradition; that's one of the options we will be working on in a later version of 4ML..."

"The authors of 4ML envision a wide community of song writers and composers who can work together on musical projects. Two composers on opposite sides of the globe could exchange musical ideas using a standard format as easily as if they were in the same room. Once a song is completed, it could be distributed using the 4ML language, and could then be converted into a potentially infinite number of formats with the press of a button. The versatility of 4ML as both a design and a distribution vehicle is what makes it so exciting to work with."

Benefits: "One of the hopes of the 4ML project is to make it a widely recognized format for music description, due to its advantages over other formats; or to promote at least its advantages to get them incorporated into whatever does become a widely recognized standard. As an XML language, basic parsing of a 4ML document is identical to parsing of any other XML document; a problem which has been solved numerous times and in almost all major programming languages. this makes it easier to write applications which use 4ML as their file format. XML is also extensible -- we can add other attributes later without worry too much about backward comaptibility; a well-formed valid 4ML file will alway sbe a well-formed valid 4ML file. Flexibility: Many music and sound mark-up languages are abstractions of sheet music, which is an abstraction of the music or even, more often, and abstraction of the operation of the equipment to produce the sounds. Since every level of abstraction removes you a step from the sounds and music themselves, it seems potentially more efficient to abstract the sound directly; fewer lossess in translation. Also, fewer limitations; western-tradition staff lines are fairly useless for abstracting many eastern traditions of music, or alternate tuning styles such as Harry Partch's 43-tone scale. 4ML intends not to be so limited..."