However, ISSNs, contrary to ISBNs, contain no information whatsoever as to the publisher or its location. They are just "dumb" numbers assigned to a standardized version of a serial title. For this reason, a new ISSN is assigned to a publication each time it undergoes any major title change.
ISSNs are assigned by a network of ISSN National Centres, usually located at National Libraries and coordinated by an International Centre based in Paris. the ISSN International Centre is an intergovernmental organization created in 1974 in the framework of an agreement between Unesco and the French Government.
The ISSN International Centre maintains a database of all ISSNs assigned worlwide, associated to records describing the publications thus identified. The ISSN Register contains more than one million entries for periodicals.