Collection IDs

There are three types of Collection Identifiers (CIDs): standard, library, and gallery.  Each of these types has its own unique prefix identifier. The structure of a CID is PRE.SEQ - where "PRE" defines the Prefix and "SEQ" defines the Sequence.

Simple document collections may be a mix of internal and external materials and will use a four-digit year as their prefix.  This year corresponds to the date the collection was created and is, in turn, defined as a series.  The sequence is an integer that increases on each collection creation.

Standard libraries will always be external and use "LIB" to denote that they are, in fact, standard library listings.  They do not have a series on their own and are rolled up within the general Library series.  The sequence, like the simple collection will be an integer that increases on each collection creation.

Standard galleries will always be internal and use "GAL" to denote that they are, in fact, standard gallery listings.  They, like standard libraries, do not have their own series and are grouped in the general Gallery series.  Also like the other two types of collections, their sequence number is an integer that increases on each new collection creation.

Within each collection, items are numbered in sequential order from the time that the collection was created.  These numbers increase from 1 to 1,000,000.  This is only true in simple document collections.  LIB and GAL use a different numbering system altogether, and may use external numbering systems such as DoD Publishing numbers, NARA identifiers, or other national or international standard.