Liber misticus (type of book containing chants, readings and prayers for the cathedral ordo) for Eastertide and the Post-Pentecost time until the day of Saints Justo and Pastor (6 August). Some of its folios are lost, including the initial and final ones. This is why it begins in the middle of the readings of the mass for the Monday of the Easter Octave and ends before the end of the mass of Saints Just and Pastor. Most of its chants lack musical notation even though their texts were laid out to bear musical notation.
Date: early-tenth century (Millares Carlo, 1961); tenth century (García Villada, 1923; Pinell, 1965; Brockett, 1968); mid-tenth century (Díaz y Díaz, 1983); mid-tenth to early-eleventh century (following Mundó, 1965: Zapke, 2007; Gros, 1978; Janini and Gonzálvez, 1977; Fernández de la Cuesta, 1980; Millares Carlo, 1999); first half of the eleventh century (Férotin, 1912; Clark, 1920); eleventh century (Riaño, 1887; Rojo and Prado, 1929); tenth century and Mundó date (Randel, 1973; Gómez Muntané, 2001); tenth to twelfth century (Pinell, 1975).
Provenance: this manuscript has been at Toledo from at least the fifteenth century, so several scholars believe that it could have been copied in Toledo (e.g. Mundó, 1965). Its notated chants use Old Hispanic vertical notation, unlike all the late manuscripts that are associated with Toledo (which use horizontal notation). This has led certain scholars to propose a provenance for this manuscript outside Toledo. E.g. Díaz y Díaz (1983) proposed León, and Brockett (1968) proposed the north of Spain. Certain fragments of chant manuscripts employed as flyleaves of late Toledan manuscripts (e.g. those in E-Mn MSS/10001) also have vertical notation, so this kind of script might reflect a given period (i.e. before the late 11th century) rather than a given provenance.