Early modern and bibliographical scholars use several different abbreviation systems for quickly and succinctly referring to the library that holds a specific rare book. These systems are often arcane, as unique identifiers for every major repository are quite difficult to craft. The two major systems in use today are MARC code list for organizations, and Short Title Catalogue location codes. MARC, or “MAchine Readable Cataloging” is a set of standards developed by the Library of Congress in the 1960s to facilitate the sharing of library records. The Library of Congress hosts a “search by code” site, for those who ever wondered what DFo was (It’s the Folger Shakespeare Library, which is in the District of Columbia). The basic pattern for MARC codes is the first letter of the state, followed by the first letter(s) of the repository. Subunits of an institution are then added, if needed: so Harvard, in Massachusetts, may be referred to generally as MH, while the Houghton is MH-H.
The Short Title Catalogue location codes are similar in theory, but different in application. Taken from A. W. Pollard, G. R. Redgrave, W. A. Jackson, F. S. Ferguson, and Katharine F. Pantzer, eds., A Short-Title Catalogue of Books Printed in England, Scotland, & Ireland and of English Books Printed Abroad, 1475-1640 (STC), 2nd edition, 3 vols. (London: Bibliographical Society, 1976-91), the STC location codes typically go with the first letter of the city the repository is in (London has 49), or an abbreviation of the repository’s name. Because it is not wholly consistent, it’s difficult to guess. The Folger is F not W, and Harvard is HD. Size trumps the pattern, perhaps? When STC information was transferred online to the ESTC, these idiosyncratic codes were replaced behind the scenes with a modified MARC code for North American holdings. The “library code” field prefaces the MARC code with a continental disambiguator: n = North America, e = Europe. In a possibly prescient move well before Brexit, Britain was not considered part of Europe for these purposes, and its libraries are prefaced with a “b”.
So it is currently possible to search the ESTC for items using MARC codes, but not the location codes familiar from the STC, which as noted in both the Folger and Harvard examples can vary quite considerably. I have taken the liberty to expand county names and some other abbreviations, and the current list repeats some information, such as place names when used in conjunction with ambiguous library names (e.g. “Public Library”). Where possible, I’ve cross-referenced against the ESTC library codes.
STC code, STC library name, any notes, ESTC code