I think this discussion began on the Autocat list as a discussion of
whether you could identify records for full-text electronic resources in
the catalog. The original questioner pointed to the lack of an
unambiguous method of identifying full-text links as a shortcoming of
MARC and our cataloging practices. I don't disagree, but maybe nobody
needed the information badly enough before to propose a change to the
format.
Respondents claimed on that list and this one that various combinations
of the 2nd indicator and the presence or absence of subfield $3 could be
used to identify full-text resources, but I think that's not only
complicated, but also unreliable. We have seen that people don't agree
on what the indicators mean and when they should be used. A reading of
the MARC 21 Format for Bibliographic Data makes it seem pretty clear
that the distinction between values "0" and "1" of the 2nd indicator
depends on whether the bibliographic record describes the electronic
resource or a non-electronic version. It's not a question of whether
the bib record describes the "constituent unit" such as a table of
contents, since this would be unlikely and would render the subfield $3
meaningless.
The MARC format gives an example of 2nd indicator "0" with subfield $3
for a table of contents, but it's hard to think under what circumstances
this would make sense. Either the location in the 856 is for the same
resource described in the bib record or it's not.
The examples in the format as well as a plain reading of the text make
it clear that if a book, for example, has a table of contents that is
also posted on the Web, that online TOC is a constituent unit of a
version of the resource described in the bib record, so 2nd indicator
"1" would be used along with subfield $3.
An argument could be made that any 856 with 2nd indicator "0" as well as
any with 2nd indicator "1" and lacking subfield $3 should point to a
full-text version of the resource, but an algorithm that relies on the
absence of something as well as a multitude of catalogers understanding
these complex definitions in the same way seems very unreliable. It
would be much more straightforward to define an indicator or a subfield
to indicate full text, if that's what people need to know.
___________________________________________________________
John Hostage Authorities Librarian
Langdell Hall [log in to unmask]
Harvard Law School Library (617) 495-3974 (voice)
Cambridge, MA 02138 (617) 496-4409 (fax)
http://www.law.harvard.edu/library/
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