e at a convenient time. So in 1991 UNIMARC/Authorities was
published."

The Permanent UNIMARC Committee, charged with regularly supervising the
development of the format, came into being that year, as users realized that
continuous maintenance - not just the occasional rewriting of manuals - was
needed. In maintaining the format, care is taken to make changes upwardly
compatible.

In the context of MARC harmonization, The British Library (using UKMARC), the
Library of Congress (using USMARC) and the National Library of Canada (using
CAN/MARC) are in the process of harmonizing their national MARC formats. A
three-year program to achieve a common MARC format was agreed on by the three
libraries in December 1995.

Other organizations recommend the use of SGML (standard generalized markup
language) as a common format for the bibliographic records and the corresponding
hypertextual and multimedia documents.

As most of the publishers use the SGML format to store their documents, a
convergence between MARC and SGML is expected to occur. The Library of Congress
set up the DTD (definition of type of document, which defines its logical
structure) for the USMARC format, because it will probably sell more and more
data both in SGML and in USMARC. A DTD for the UNIMARC format has also been
developed within the European Union. In his study L'acces aux catalogues des
bibliotheques par Internet (The Access to Library Catalogs through the
Internet), Thierry Samain specifies that some libraries choose the SGML format
to encode their bibliographic data. In the Belgian Union Catalog, for example,
the use of SGML allows one first to add descriptive elements stemming from the
MARC format and other formats, and second to facilitate the production of the
annual CD-ROM.

The libraries also have to adapt their thesauri and their key-word lists. In
international bibliographic databases like the OCLC Online Union Catalog, the
absence of a universal thesaurus is a real problem when you try to find
documents using the search by subjects. In Europe, each country uses thesauri or
key-word lists in its own language, whereas multilingual thesauri would be
essential.

Another problem is the harmonization of software. From January to December 1997,
ONE (OPAC Network in Europe) was a collaborative project involving 15
organizations in eight European countries. This project provided library users
with better ways to access library OPACs (online public