1. A computer-implemented method of distributing digital sheet music to a plurality of users via a network, wherein a server operated by a distributing party receives requests from the plurality of users, comprising: receiving, by the server from a first user over the network, first digital sheet music data representative of a song arrangement for a predetermined instrument, the first digital sheet music data encoded in a predetermined format and comprising a first data portion, a second data portion, and a notation parameter portion, the first data portion including at least one set of predetermined notation data selected from the group consisting of musical notes, tablature symbols, chords, and song text that are musical elements of the song arrangement, the second data portion including at least one set of first supplemental notation data that is supplemental to the musical elements of the song arrangement, the first supplemental notation data selected from the group consisting of fingering information, a translation into another language of song text, textual or audible pronunciations of song text, editorial markings, supplemental tablature symbols, alternate pitches or parts, page turn information, version comparison information, and hyperlinks to information relevant to the song arrangement, and the notation parameter portion indicative of at least one customizable notation parameter within the first supplemental notation data; receiving, by the server from a second user over the network, a first request for second digital sheet music data representative of the song arrangement for the predetermined instrument; processing, by the server, the first request; generating, by the server, the second digital sheet music data, the second digital sheet music data encoded in a predetermined format and comprising the first data portion and a fourth data portion including at least one set of second supplemental notation data that is supplemental to the musical elements of the song arrangement and differs at least in part from the first supplemental notation data, the second supplemental notation data selected from the group consisting of fingering information, a translation into another language of song text, textual or audible pronunciations of song text, editorial markings, supplemental tablature symbols, alternate pitches or parts, page turn information, version comparison information, and hyperlinks to information relevant to the song arrangement; wherein the server generates the fourth data portion by executing instructions comprising, receiving profile information associated with the second user, selecting at least one customizable notation parameter among those indicated by the notation parameter portion, and based at least in part on the profile information, modifying at least one parameter value of the first supplemental notation data that corresponds to the selected customizable notation parameter, thereby generating supplemental notation data that is customized for the second user; and providing, by the server, the second digital sheet music data to the second user.