1. Introduction

   As part of the validation process for the development of URNs the
   IETF working group agreed that it is important to demonstrate that
   the current URN syntax proposal can accommodate existing identifiers
   from well established namespaces.  One such infrastructure for
   assigning and managing names comes from the bibliographic community.
   Bibliographic identifiers function as names for objects that exist
   both in print and, increasingly, in electronic formats.  RFC 2288
   [Lynch] investigated the feasibility of using three identifiers
   (ISBN, ISSN and SICI) as URNs.

   This document will analyse the usage of national bibliography numbers
   (NBNs) as URNs.  The need to extend analysis to new identifier
   systems was briefly discussed in RFC 2288 as well, with the following
   summary: "The issues involved in supporting those additional
   identifiers are anticipated to be broadly similar to those involved
   in supporting ISBNs, ISSNs, and SICIs".

   A registration request for acquiring a Namespace Identifier (NID)
   "NBN" for national bibliography numbers has been written by the
   National Library of Finland on the request of the Conference of
   Directors of National Libraries (CDNL) and the Conference of the
   European National Librarians (CENL).  Chapter 5 contains a URN
   namespace registration request modeled according to the template in
   RFC 2611(-> 3406).

   The document at hand is part of a global co-operation of the national
   libraries to foster identification of electronic documents in general
   and utilisation of URNs in particular.  Some national libraries,
   including the national libraries of Finland, Norway and Sweden, are
   already assigning NBN-based URNs for electronic resources.

   We have used the URN Namespace Identifier "NBN" for the national
   bibliographic numbers in examples below.