Antiphonals are music manuscripts which contain the sung portions of the Divine Office. Regularly used in religious services, antiphonals were usually large in format so the entire choir could sing from a single volume. Singers were guided by the black neumes, written on four staves, which indicate the melodies and repetition of the music. This manuscript was created for the Order of the Most Holy Saviour, also known as the Bridgettines, a monastic order of Augustinian nuns. The decorated initial (one of two within this particular manuscript) marks the beginning of the services for the canonical hours on folio 45r.