Notated music forms the basic source material for musicology. It is the basis of most musical performance, especially in classical Western art music. It is also often used to record and describe performed music not based on a notated text. Notated music has been produced in the West for more than one thousand years. A vast quantity of notated scores, in both printed and manuscript forms, is stored in the world's libraries. However, only a small portion of this music is available in digital form, and usually as image files. An even smaller portion is available digitally in a machine-readable form that represents the structural and semantic information contained in written or printed scores and that would facilitate computer-assisted research.
A commonly accepted digital, symbolic representation of music is necessary in order to move musicology into the modern era; that is, to make it possible to carry out the same kinds of operations that are commonly performed on electronic textual sources, for example, compiling musical corpora, data interchange, and comparative analysis. Also, because music research routinely combines the study of manuscript sources, printed music editions and time-based media, an encoding mechanism that facilitates the creation and management of relationships between components of digital versions of these materials will lead to improvements in research efficiency.
Seeing the need for a comprehensive markup language in the music community, in 1999, Perry Roland of the University of Virginia set about creating an XML schema (DTD) for the representation of music notation. Eventually this DTD became known as MEI because it was influenced by the same principles that guided the creation of the Text Encoding Initiative (TEI).
The Music Encoding Initiative (MEI) DTD is an XML DTD for the representation and exchange of music information. It is designed to be comprehensive, that is, it provides ways to encode data from all the separate domains, i.e. logical, visual, gestural (performance), and analytical, commonly associated with music. In addition, the DTD accommodates bibliographic description that is required for archival uses. It also addresses relationships between elements, cooperative creation and editing of music markup, navigation within the music structure as well as to external multimedia entities, the inclusion of custom symbols, etc. Unlike other music representation schemes, MEI can record the scholarly textual apparatus frequently found in modern editions of music.