http://www.rfc-editor.org/rfc/rfc3044.txt
RFC 3044: Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace, S. Rozenfeld2001-01-01T23:00:00-00:00This document presents how the ISSN - International Standard Serial Number - which is a persistent number for unique identification of serials widely recognised and used in the bibliographic world, can be supported within the Uniform Resource Name (URN) framework as a specific URN namespace identifier. This memo provides information for the Internet community.