Many manuscripts acquired by the University Library before the middle of the nineteenth century either originated as or were made up into bound volumes, and were classified alongside printed material. Most carry what is known as a 'two-letter' reference, running (for western manuscripts) from Dd.1.1 through to Oo.7.60. They comprise mainly medieval and early modern manuscripts. This catalogue is based on entries for western post-medieval manuscripts in the 5-volume Catalogue of the Manuscripts preserved in the Library of the University of Cambridge (Cambridge, 1856-1867). Manuscripts that are wholly or largely in Greek script are not included. For finding aids for medieval and non-Western manuscripts in the two-letter class, see 'Other finding aids'. After the mid nineteenth century, the two-letter class was superceded by the Add. (Additional) class.