The abstract library system model defines basic components and structure of circulation and catalogs. A particularly interesting component is the ARMS database system . Presently the circulation component of the abstract model is the most well defined. Circulation A circulation control system at the most primitive level is made up of a set of items called the collection and a set of locations and describes the relationship and rules of behavior between these two sets. A location is an abstraction that represents any entity that can possess an item or indicate the state of an item.
Locations can be tangible things like borrowers or the library itself.
A location can contain anywhere from 0 items to the total number of items in the collection. The relationship between the collection of items and locations can be expressed in a 2D matrix, or table, with items along one axis and locations on the other axis. Otherwise there is a 0. Such a table is called a Charge Transaction Matrix . A charge will move an item from the home location to any specified location.