5. Work Letters. For different editions published in the same year, assign a work letter B-Y after the date. (The work letter A is reserved locally for photocopies; Z for incomplete dates).
6. Photocopies. (Local practice) Photocopies always have a date in the call number; the date is always followed by capital A, e.g. 1893A. The call number date of a photocopy is always the original date of publication, not the date of publication of the photocopy edition. A book originally published by Princeton University Press in 1954 and reprinted as a photocopy by University Microfilms in 1984 would have the call number date 1954A.
For added copies, current practice is to create a separate bibliographic record for the photocopy if the bibliographic record for the first copy is for the original and the copy to be added to the collection is a photocopy. All subsequent photocopies should be recorded as MFHDs linked to the bibliographic record for the photocopy. LC call numbers for copies linked to the photocopy record should have A following the date.
Former practice permitted adding of photocopy MFHDs to a record for the original if the added copy was for the same location. In that case, the date in the call number did not get an A.
Photocopies are generally issued "on-demand" primarily by UMI/Proquest or prepared locally by Yale Preservation. Do not confuse photocopy numbers with call numbers for reprint editions, where a different publisher reissues a set of copies using the same typeface as the original, often including a reproduction of the title page. Reprint edition call numbers take the date of publication (without A), not the date of the original. Rule of thumb: for photocopies, the actual publisher is identified in the 533 field and the original publisher is identified in the 260 field; for reprint editions, the actual publisher is identified in the 260 field and the original publisher is identified in a 500 or 534 field.