On Wed, 15 Oct 1997, Graham Barr <graham@DRA.COM> wrote:
> Let's say that a periodical is published simultaneously in paper format
> and in microform.  Would this periodical have one ISSN or two different
> ISSN's (one for each format)?  I'm assuming it would have two
> bibliographic records (one for each format)

Separate ISSN are assigned to separate physical formats, including
electronic (online, CD-ROM).  There is one exception to this policy and
that is for reproductions by a secondary publisher.  Examples of this
exception would be microforms of print serials reproduced by University
Microfilms, or serials in projects such as JSTOR.  Policies for how many
bibliographic records are needed are governed by cataloging rules, by
local practice, and by other policies such as those of the CONSER program
and may not always equate to how many ISSN are issued.

Regina  R. Reynolds                     email: rrey@loc.gov
Head, National Serials Data Program     voice: (202) 707-6379
Library of Congress                     fax    (202) 707-6333
101 Independence Avenue, S.E.           ISSN Web page: lcweb.loc.gov/issn/
Washington, D.C. 20540-4160