Group of data elements comprising a code or identifier and a phrase or pointer indicating a list or source of an authoritative list of values Code, URI or identifier Direction to a definitive list of values within which an identifier or code is unique such as a URL or URN Phrase indicating a definitive list of values within which an identifier or code is unique such as a URL or URN Group of data elements identifying a bibliographic resource that is wanted by a requester. Authoritative source of bibliographic information used to identify or locate an item. Group of data elements estimating the ease of locating and obtaining a copy of a particular bibliographic resource. Code indicating or estimating whether or not a bibliographic work or manifestation is currently available through its normal distribution channels. In Print Out of print other unknown Text string indicating or estimating whether a bibliographic work or manifestation is protected by copyright law and optionally indicating the current owner of copyright. Text string indicating or estimating how difficult it is to locate a copy of a bibliographic work including known institutions possessing a copy within a geographic area.