This Codex comprises the oldest complete surviving neumed mass
antiphonary; it includes assorted appendices (such as Alleluia
verses, Antiphons and Psalm verses for the Communion Antiphons).
Because the mass antiphonary is complete, the manuscript remains
important to this day as a resource for Gregorian chant research.
The second part of the codex contains the Libyer Ymnorum, the
Sequences of Notker of St. Gall. Recent research has established
that the codex was written in Einsiedeln itself (in about 960-970),
most likely for the third abbot of the cloister, Gregor the
Englishman.