Oxford, Bodleian Library, e Mus. 100
From Clavis Canonum
The three volumes that are today Oxford, Bodleian Library, e Mus. 101, 100, and 102 (= Summary Catalogue nos. 3687, 3686, and 3688) are parts of the same manuscript, the only known copy of the Collectio Iustelliana.
For details, see Oxford, Bodleian Library, e Mus. 101.