Sheet music for musical theatre has a special vocabulary:
Vocal Scores contain all the songs for a musical, arranged for piano accompaniment, sometimes with cues before the songs. The songs will be in the original keys. These will be the editions used by performers to prepare for stage performance.
Vocal Selections contain the most important songs from a musical, arranged for piano accompaniment. The songs are sometimes edited or transposed to different keys. Sometimes these are the only published songbooks for a musical, especially a recent musical.
Anthologies contain songs from a variety of musicals, usually for a specific voice type or songs by a single composer. The most important series is the Singers Musical Theatre Anthology, which has several volumes for each voice type, volumes for teens and collections of audition excerpts, plus CDs of the accompaniment. Another anthology is The Contemporary Singing Actor (divided into men's, women's and duets volumes)
Bracken Library uses the Library of Congress system for numbering books on the shelves. The following numbers apply to scores (sheet music) for musical theatre:
M 1503 Vocal score of operas, operettas or musicals (complete songs in original keys, with piano accompaniment
M 1507 Anthologies of vocal music, inlcuding musical theatre anthologies
M 1508 Vocal selections of a single musical (may be transposed)
M 1527 Songs from motion pictures or television shows
M 1630.18 Song books devoted to a single composer, singer or topic