A name given to a collection of business functions, entities, programs, and tables that can be further described by system documentation of various forms. It is typically used to describe a unit of related work such as in a project, subsystem, or data subject area. The status of an application system may change (e.g. it may be frozen), and new versions may be created. It is also a unit of access control to the collection of elements that it contains. Elements may be shared between application systems.