Liber misticus (type of manuscript with chants, readings and prayers for the Hispanic rite's cathedral ordo). It contains the public liturgy for St Martin (ff. 1r-51v), St Aemilian (ff. 52r-88v), and for the Assumption of the Virgin Mary (ff. 88v-99v, in its largest extant version). The readings for the liturgy of these days includes Saint Martin's vita by Sulpicius Severus and St Aemilian's vita by Braulio of Zaragoza. Its notation is vertical but there are some chants using Aquitanian notation added to the margins of ff. 1r y 51v-52r; there are also diagrams using alphabetic notation added on ff. 98v-99r in the late twelfth or early thirteenth century.

Date: mid-eleventh century or second quarter of the eleventh century (Boynton, 2011, 2007 and 2002); mid-eleventh century (Mundó, 1965); eleventh century (Fernández de la Cuesta, 1983; Clark, 1920; Férotin, 1912); tenth century or, following Mundó, mid-eleventh century (Gómez Muntané, 2001; Randel, 1973 and 1969); tenth century (Pinell, 1965 and 1957; Brou, 1955) 2013-15; Millares Carlo et al., 1999; Rojo y Prado, 1929; Férotin, 1912); twelfth century (Riaño, 1887, though he also lists this manuscript under the heading for eleventh and twelfth century manuscripts).

Provenance: Monastery of San Millán de la Cogolla (proposed by Boynton, 2011, 2007 and 2002, because it contains the only extant long version of the Hispanic rite office of St Aemilian, including a prayer that mentions him as a patron – though this Saint was a patron of many churches in Northern Spain – and because she finds similiarities between its musical notation and that in E-Mah Cod. 56); possibly northern Spain (Randel, 1973 and 1969, based on its notation and melodic characteristics). Boynton (2002) indicates that there was a Vita of St Aemilian listed in a thirteenth century catalogue of Silos, which could refer to this misticus, and notes that the inventories of the Chapter Library of Toledo's Cathedral do not mention any codex that could be identified with this one until the thirteenth 1455, and thus proposes that it arrived in Toledo in the fifteenth century. Francisco Santiago de Palomares made copies of some folios of this manuscript when he was working for Burriel in Toledo Cathedral. In 1869 Don Críspulo Avecilla did some other copies of this manuscript for Barbieri. Riaño also made copies for Barbieri, but the place where the manuscript was held at that time is unknown. Archer Huntington (1870-1955), founder of the Hispanic Society of America, acquired this manuscript sometime between 1895 and 1914 (Boyton, 2009) and the scholarly community ignored that it was held in the Library of this Society until Boynton found it there in 2001.

Liturgical tradition: A

Randel responsorial tone tradition: La Rioja