This is a Special Purpose Artist. Musical theatre soundtrack releases should generally be attributed to the songwriter(s)/author(s) per Musical Soundtrack Style. Only use this SPA if you really cannot identify either the songwriter(s) (or in the case of tracks/recordings, the performers, if the printed tracklists so indicate them). This SPA is particularly meant for unnamed ensembles (groups of unnamed performers), which in musical theatre recordings are often described typically as, eg. “Company”, “Ensemble”, “Chorus”, etc, with those descriptions or other character roles applied as the artist credit. (In the case of unnamed individual artists, the use of the unknown SPA is more suitable.) More details at Musical Soundtrack Style.
Use this SPA sparingly; often you can get by without using it even when unnamed ensembles are included in the track/recording credits. Unless those ensembles are the only credits, or are the first in sequence to be named in the credits followed by others, you may include such 'credits' with just intermediate or trailing phrases, without resorting to using this SPA. eg: see this tracklist.