Accession number (cultural property)
In galleries, libraries, archives, and museums, an accession number or catalogue number, or various other terms, is a unique identifier assigned to each object in a collection for its identification and recording. Assignment of accession numbers typically occurs at the point of accessioning, when the object enters the collection, or sometimes in later cataloging.
Source: Wikipedia — Accession number (cultural property) (CC BY-SA 4.0)