In December I asked the question in the subject on the Libraries and
Information Science StackExchange:

"In many MODS records harvested from several sources, I see
<mods:publisher>s.n.</mods:publisher> or something similar (worst I
have seen: 000NOPUBLISHER000) to indicate the publisher is unknown or
that there is no 'official' publisher. For unknown information, I
think leaving elements out makes sense. However, for information known
to be missing, something else may work better.

Are there special field values (perhaps "unknown") or structural
elements (perhaps 'unknown="true"') to indicate 'this value is known
to be missing'?"


But later I realised this list is more appropriate for my question. I
think I read most of the guidelines and I searched the recent archives
and found Thomas Scheffler's question and following discussion on "et
al." and "and others" and a quote by Nathan Humpal "... using s.l., or
any <place> element at all, if the place name is not known is advised
against". There was an exchange in July 2003 about qualifiers for
'knownness' of elements like names and dates, but it seems they (e.g.
@qualifier="unknown") have not made it to the schema definitions.

Can I say that in general, there is no way of saying part of a record
is unknown other than by leaving it out and perhaps making a mods:note
of it? And (if it is indeed semantically different) if some
information is known to be missing (e.g. the 'et al.' case)?

Thanks in advance. (Perhaps I should add that I'm not a cataloguer or
librarian in general. :-))

Ben Companjen

P.S. Feel free to answer or comment on the LIS SE.