A unique combination of letters and numbers used to identify an item and to facilitate storage and retrieval.
'Call number' is used more commonly in libraries than in archives. A call number frequently consists of a class and a shelf number. (Shelf numbers are also called cutter numbers, book numbers, or author numbers.) For example, the call number TR 15 .P43 consists of the Library of Congress classification for photographic collections (TR 15) and a shelf number (.P43) to give the work a unique number.