The library occasionally acquires or decides to re-process collections that have been previously cataloged with a distinct numbering system. If the archivist identifies such a numbering system in the course of surveying a collection, it is important to note this and consult with the Manuscript Unit Head, Head of Processing, and the curator about its significance and current importance.
In some cases, the existing numbering system is firmly established in the scholarly community, and may even be published in authoritative bibliographies or indices (e.g., the “Pottle” numbers in the Boswell collection, or the “McKay” numbers in the Stevenson collection). If the archivist determines that the existing system is so well known that their omission from the new finding aid would cause confusion among researchers and access services staff, references should be included as folder notes in the finding aid or in an appended concordance. Appropriate explanatory notes can be included in the front matter. For an example, see the Boswell Collection (GEN MSS 89).
Former call numbers are also recorded in the Processing Notes field of the finding aid.