The index follows the Arabic folio numbers in the upper right-hand corner of each recto, although damage to the codex has often obscured them. These numbers were added after two groups of folios had been bound out of order in the Sanctorale section: the table below records their correct sequence.
1-200: Temporale and Sanctorale to Agatha
217-224: Agatha to Phillip and James
201-216: Phillip and James to Peter
225-273: Peter to Common of Apostles
No folios appear to have been lost due to this mistake; however, there is a remarkable and unexplained absence of the Sanctorale in the manuscript during the month of July, indicated by the leap from the single antiphon for St. Mustiola (July 3) to St. Laurence (August 10) on f. 231r.
The confusion caused by the binding error is compounded by the manuscript's occasionally unusual liturgical ordering. For example, music for the Exaltation of the Cross (September 14) appears in two locations: f. 202v, following the Finding of the Cross (May 3); and f. 246r, in its expected position. A similar arrangement occurs for music for the feast of the Assumption (August 15): in the expected position for this feast (f. 235r), the invitatory and series of responsories appear to be of northern Italian provenance (with concordances only with Hesbert's Ivrea and Verona manuscripts in CAO); more widely disseminated chants are included as alternates for the Matins of Assumption but in an unexpected location, following the Nativity of Mary (f. 244r).
Some of the peculiar arrangements in the Temporale seem to reflect a relaxed approach to the liturgical assignment of chants or series of chants. For example, antiphons presumably for the psalms of Lauds following the Octave of Easter (f. 116v), but not assigned to any particular day, are followed by a list of antiphons "in evangelio" for the five Paschal Sundays following the Octave (f. 117r), including the Sunday after Ascension.
These lists of antiphons are succeeded by two series of Paschal responsories (beginning on f. 120v and f. 123r), separated only by a single antiphon. The only rubric which gives any indication of the liturgical function of these chants precedes the first set of responsories and indicates that some of their texts are taken from the book of Revelations. These responsories are then followed by the feast of the Ascension (f. 125v). (The Common of Paschal Martyrs, it should be noted, has been included within the Sanctorale, f. 221v.)
Lack of adequate rubrics makes the assignment of chants to a particular liturgical occasion difficult in other cases, as well. Clusters of antiphons and responsories during the pre-Lenten penitential season are given no rubrics at all: their assignment by the indexers to Septuagesima, Sexagesima, or Quinquagesima is somewhat arbitrary. The same is true for a series of antiphons presumably intended for Eastertide memorials to the True Cross (f. 107r). In order to reflect the manuscript's lack of specificity, some fields in the index (liturgical occasion, Office, and position) have been assigned very general designations.
Unfortunately, water and other damage have rendered many of the folios largely, if not completely, illegible. Faint or invisible musical notation has led the indexers to indicate uncertain modal or differentia assignments by question marks. However, the only folios actually missing from the manuscript are at the end. Some information concerning the missing Common of Martyrs may be reconstructed from incipits listed as alternate chants on the feast of the Holy Innocents (ff. 185v-187v).
Differentiae have been numbered arbitrarily, and all chants not found in CAO have been assigned numbers prefixed by "mza".