This document defines and promotes the use of a standard code (ISSN) for the unique identification of serials and other continuing resources. Each International Standard Serial Number (ISSN) is a unique identifier for a specific serial or other continuing resource in a defined medium whether print or electronic. This document also allows for grouping related resources into clusters identified by specific ISSNs. ISSNs are applicable to serials and to other continuing resources, whatever the medium of production and irrespective of whether the serial is from the past, the present or is planned for the foreseeable future. Continuing resources include: – serials such as newspapers, periodicals, journals, e-journals, magazines, continuing monographic series, annual reports, and, – ongoing integrating resources in print or electronic medium that are continually updated like loose-leaf publications, websites, ongoing directories and databases. Individual monographs, sound and video recordings, printed music publications, audiovisual works and musical works have their own numbering systems and are not specifically mentioned in this document. Such items may carry an ISSN in addition to their own standard numbers when they are part of a continuing resource. More detailed operational guidance is provided in the ISSN Manual available from the Registration authority for this document (see Clause 11 and Annex D).