Liber ordinum, i.e. book containing the material necessary for administering sacraments and votive rituals, as well as prayers and blessings for a variety of special objects and occasions. The type of ordinum of this manuscript is "maior vel aepiscopalis", i.e. "major or for a bishop". This liber ordinum maior has three parts. It includes a calendar (ff. 1r-3v, not ff. 1r-6v, as stated by Vives and Fábrega, 1949, because they describe by mistake E-SI MS 3 as E-SI MS 4, and by Janini, 1977, and González Barrionuevo, 1992, very likely following Vives and Fábrega); an index for the material included in the rest of the manuscript (ff. 4r-8v); and two main sections, a first section with the liturgical material for ministering sacraments and special rituals of Holy Week (ff. 9r-165v), and a second section with a collection of votive masses (ff. 166r-344v).

Date: 18 May 1052 (f. 332r: "ERA TLXLA XV K[a]L[endas] I[unia]s").

Origin: depending on the interpretation of the colophon (in ff. 331v-332r: "exaratum est hunc ordinem libru[m] per Iussione[m] dom[i]no d[omi]nicus presb[yt]er qui et abba ex cenobio s[an]c[t]i prudentii amminiculante [sic, it should be "adminiculante"] santio garzeiz de monte albos"...] different authors have ascribed it to either the monastery of San Prudencio Laturce in La Rioja, or to the monastery of San Martín of Albelda in Huesca.

Scribe: presbyter Bartholomeus, according to colophon "Ego bartolom[eu]s licet indign[u]s pr[e]sb[y]ter" (f. 331v).

Liturgical tradition: A.

Randel responsorial tone melodic tradition: La Rioja, but "not entirely free of León symptoms", according to Randel, 1969, p. 67.