Description from the library online database:
[Musiktheoretischer Sammelband]
Entstehungsort: vermutl. im süddeutschen Raum
Entstehungszeit: 1200-1250
Provenienz: Die Pergament- und Papierhandschrift stammte aus dem Besitz des Schweizer Humanisten und Universalgelehrten Heinrich Loriti Glareanus (1488-1563) und enthält zahlreiche Glossen und Kolumnentitel aus seiner Feder. Glareans Bibliothek erwarb der spätere Augsburger Bischof Johann Egolph von Knöringen (1537-1575) während seiner Freiburger Studienzeit; er vermachte seine über 6.000 Bände zählende Bibliothek als Stiftung 1573 der UB Ingolstadt.

[Translated:
Volume of collected writings on music theory
Place of origin: presumably southern Germany
Date of origin: 1200-1250
Provenance: This parchment and paper manuscript came from the possession of the Swiss humanist and polymath Heinrich Loriti Glareanus (1488-1563) and contains numerous commentaries and headings by him. Glareanus's library was bought by the later bishop of Augsburg, Johann Egolph von Knöringen (1537-1575), during his time as a student in Freiburg; in 1573, he bequeathed his library of more than 6000 volumes to the University Library of Ingolstadt as an endowment.].

A two-voice Gloria is found on folio 15r.

Differentiated black neumes; letters 'c' and 'f' used for clefs; flat sign preceding a note.

6 red and black lines alternating with two clefs (c and f) and the music written in score apparently using the top three lines for the upper (c) part and the lower three lines for the f-clef part. One flat is written on the line.

Full inventory of the music pieces provided by Jos Haring (2021), including both the folio numbers and the manuscript's page numbers. Haring also notes that the titles of the musical exercises at the beginning, up to fol. 5v, were written in later by Glareanus:

Textless music exercises from "De Musica" by Joannis de Affligem 3v Deductio ex Γ (p. 4)
3v Deductio ex Cfaut (p. 4)
4r Deductio ex Ffaut (p. 5)
4v Deductio ex G. (p. 6)
5r Deductio ex csolfa (p. 7)
5r Deductio ex ffami (p. 7)
5v Deductio ex g (p. 8)
6r Terterni sunt modi quibus omnis canta (p. 9)
7r Amen (p. 11)
15r Gloria a 2 (p. 25)
15v Music examples (from "De Musica" by Joannis de Affligem) (p. 26)
22r Quos fecissti veritatis lumen agnoscere (p. 39)
22r Hodie precessit ad ortum (p. 39)
22r Maria ave risolis mater libera (p. 39-40)
22v Vox clamantis in deserto (p. 40)
22v Hunc ius celso veniens olimpho (p. 40)
23v Collegerunt pontifices per pharisei concilium (p. 42)
24v Resp.: Ego propter roga in petre (p. 44)
25r Bethleem civitas dominator (p. 45)
25r Pro ego nesciebam (p. 45)
25r Die sollempnitatis (p. 45)
25v Sapienciam per rei facit sunt incogitationibus (p. 46)
25v Oravi deum meum (p. 46)
25v Domus mea domus orationis (p. 46)
26v Ancilla cristi sum ideo (p. 48)
27r Laudate dominum de celis a 2 (p. 45)
33r Ter tria iunctorum sunt intervalla sonorum (p. 61–62)
35r Seculorum Amen examples (p. 65–69)
37v Qui sunt ut quales cuiusque modi speciales (p. 70)
38r Possidet antiphonas primo (p. 71)
38r Tercius hic modus (p. 71)
38r Conveniunt quarto (p. 71)
38v Sic quinti sedes proprias (p. 72)
38v Sextus (ht) varias sibi (p. 72)
38v Septimus his fruitur (p. 72)
39r Iure sub octavi resonant (p. 73)
39r Cognita gradatim omnium intensione (p. 73)
39v Protus finit inlicanosipaton (p. 74)
39v Deuterus finit mypatemeson(p. 74)
40r Tritus finit inparipatemeson (p. 75)
40r Tetrardus finit inlicaonsineson (p. 75)
40r Plagis tetrardi remititur (p. 75)
40r E voces unisonas equat .s. semitonis distantiam (p. 75)
40v Unus deus est trinitas (p. 76)
41r Benedicens ergo deus (p. 77)
42r Quamuis mille modis (p. 80)

Examples from Micrologus by Guido of Arezzo

45r Summi Regis archangele Michael (Musical gloss by Glareanus) (p. 85)
47r Tercia dies est quo hec facta sunt (p. 89)
47v Primum querite regnum dei (p. 90)
50r Sancte Iohannes (?a 2) (p. 95)
50v Linguam refrenans temperet (p. 96)
51r Miserere mei deus (diaphonia a 2) (p. 97)
52r Ipsi soli servo fidem (organum a 2) (p. 99)
52r Homo erat in Iherusalem (organum a 2) (p. 99)
52r Veni ad docendum (organum a 2) (p. 99)
52v a. Sexta hora sedit super paterum (organum a 2) (p. 100)
52v b. Sexta hora sedit super paterum (organum a 2) (p. 100)
52v Victor ascendit celos (organum a 2) (p. 100)
52v Venite ad oremus (organum a 2) (p. 100)
55v Spera in domino (p. 106)
55v Sancti spiritus adsit nobis gracia (p. 106)
60v UT queant laxis REsonare fibris MIra gestorum FAmuli (p. 110)
61r Alme recor mores nobis (p. 117)
61r Salus nostra honor noster esto deus
61r Tibi totus servuit mundus une deus
61r Summe pater servus tuis miserere
61v Deus iudex iustus fortis et patiens (p. 118)
61v Stabuire vista ante deum semper ieri
61v Domino laudes omnis creatura dicat
62v Tu patris sempiternus et filius (parallel organum a 4) (p. 120)
62v Primum querite regnum dei
62v Secundum autem simile est huic
63v Spera in domino et fac bonitatem
64r Spiritus alme illustrator hominum (p. 123)
64r Spiritus domini replevit orbem terrarum alleluia
76v Primi toni melodiuam psallas indirectum (p. 148)
76v Secundum autem in fine & in medio
76v Tercium suspendit in medio & in fine
76v Quartus gradatis ascendit
76v Quinti medietas secundo similis
76v Sextus ut primus imponteur
76v Septimus quartum in medio respicit
76v Octavus quinto respondens
76v explanation of neume types

Dominique Gatté, 2019