W. M. Lindsay, An Introduction to Latin Textual Emendation

1 In the “scriptorium” of every monastery there was an official, known as the “corrector,” whose duty was to revise a MS. as soon as it had been written, and collate it with its original or with some other MS. of the same work. The “corrector” of the first eight plays in B I believe to have used in his revision not the actual original from which B (as well as D) was copied, but the archetype itself, the original of the original of BD (see p. 7 above). In the same way the Laurentian MS. of Nonius has had valuable readings introduced into its text by a “corrector,” who may have used for this purpose the actual archetype of all our MSS. (Class. Rev. x. 16). “Mixed” texts, which cannot be referred to one or other of two “families” of MSS., are to be explained by the supposition that a text copied from an original of one family has been corrected, either at the moment of its production or later, from a MS. of another family.

2 In B these omissions are indicated by a small d (for deest) in the margin. The letter has usually been erased by the “corrector” when he added the word required (e.g. Cas. 361), but traces of it sometimes remain (e.g. Cas. 64, 347).