I would think most users would expect a unique hit, yeah, the
expectation is generally that a link like that is an 'identifier'
representing a single record. That's even kind of implied by the word
"permalink" to me, my assumption is that a "permalink" is a link to a
particular record, rather than to "search results".
The most inconvenient case is going to be when there are two (or more)
hits for a given LCCN, and one of them represents a correct match, and
one a cancelled/invalid match. The client software in question may end
up using the 'wrong' hit.
It's not a problem unless an 010$z on one record has not been re-used as
an 010$a on a different record. But it's not entirely clear to me in
what cases this may occur.
Perhaps the documentation could discuss this issue, and make it clear
that multiple record can come back from a permalink, and give some
examples of cases where this might occur, especially cases where an
010$z on one (or more) record is also an 010$a on one (and only ever
one, I think? There can't be the same 010$a on two different records can
there?) record.
On 9/7/2011 5:27 PM, Della Porta, Ann wrote:
Jonathan,
When LC first released the LCCN Permalink service in 2008, we considered
whether to index the canceled LCCNs -- and decided yes, we needed to provide
access to both 010a and 010z. Here's the rational: LCCNs are an identifier
that dates back to 1898. Most cancelled LCCNs represent a record that was
previously distributed by LC's Catalog Distribution Service.
For bibliographic records, sometimes these older LCCN appeared on printed
cards -- and newer versions of the record have been assigned a different LCCN.
LC has to assume that other libraries may have entered these older (and now
cancelled) LCCNs into their catalog records in the 010a field. In other cases,
publishers and others print invalid or cancelled LCCNs in their CIP data
(sometimes a publisher may apply for both PCN and CIP data for the same
content; sometimes the same LCCN is simply used on different titles). In
addition, there are rare cases where the same LCCN has inadvertently been
assigned to two records (an error LC corrects as soon as we are aware of the
situation).
For authority records, we face an additional issue. There are times when
records for the same heading enter the master name authority file from multiple
nodes on the same day. In this case, one record is retained and the duplicate
cancelled. For subject authorities, we have situations where one heading is
split into two or more separate headings. In this case, the split records
receive new LCCNs and the older LCCN is entered as an 010z on the new heading
records. In addition, we have situations where a name authority might be moved
to subjects or vice versa; in this case, the original LCCN is again often
retained in 010z.
We still assume that some folks want to be able to retrieve something.
Therefore, for the LCCN Permalink service, LC decided to cast the LCCN net more
broadly than the 010a. In the infrequent situation where multiple records are
retrieved, all hits will be displayed on the LCCN Permalink presentations for
that identifier.
Do you think that most users expect a "unique" hit?
Ann
-----Original Message-----
From: Jonathan Rochkind [mailto:[email protected]]
Sent: Wednesday, September 07, 2011 2:16 PM
To: Next generation catalogs for libraries
Cc: Della Porta, Ann; Code for Libraries
Subject: Re: [NGC4LIB] Permalink service for authority data now available at LC
Very nice, thanks.
I wonder the rationale behind searching both valid and cancelled LCCNs.
This has caused me trouble in the past in similar systems, because a cancelled
LCCN seems in some cases to duplicate a different valid LCCN, so you search on
an LCCN, and get, in this case, both the correct record and and an incorrect
record -- the requirement that software take account of this and look into the
records to see which is the valid one adds significant complexity to the
software, and is also a detail likely to be overlooked in client software
implementation.
I wonder if any alternatives were considered. I'm not exactly sure what the
solution is though -- if it wasn't for the _collision_ issue, then we could say
requesting a permalink for a cancelled LCCN should result in an HTTP redirect
to the permalink for the correct LCCN. But a cancelled LCCN on one record can
be identical to a correct LCCN on another, or theoretically the same cancelled
LCCN could exist on more than one record -- making it unclear what design could
be better.
On 9/7/2011 1:55 PM, Della Porta, Ann wrote:
Apologies for cross posting.
The Library of Congress is pleased to announce an expansion of its LCCN Permalink
Service for the Library's name and subject authority records. These persistent URLs
are based on the Library of Congress Control Number (LCCN). As with bibliographic
records, LCCN Permalinks are displayed on authority record entries in LC
Authorities<http://authorities.loc.gov>.
Create an LCCN Permalink
Simply begin your URL with the LCCN Permalink domain name --
http://lccn.loc.gov/ -- then add an LCCN.
Examples: http://lccn.loc.gov/n79018774 or
http://lccn.loc.gov/sh85026371
LCCNs should be formatted according to the
info:lccn<http://info-uri.info/registry/OAIHandler?verb=GetRecord&metadataPrefix=reg&identifier=info:lccn/>
URI specification. Instructions are also available in the LCCN Permalink
FAQ<http://lccn.loc.gov/lccnperm-faq.html>.
How LCCN Permalink Works
An LCCN Permalink retrieves a MARCXML-formatted record using the Z39.50/SRU protocol. Both valid and
cancelled LCCNs (MARC 21 fields 010a and 010z) are searched. Authority record displays for LCCN
Permalink follow the labeled display found in LC Authorities. MARCXML and MADS versions of the records
are also available. Displays link to entries in LC Authorities<http://authorities.loc.gov> and
the LC Online Catalog<http://catalog.loc.gov> -- and, where appropriate, to entries in the
Virtual International Authority File<http://viaf.org> and LC Authorities and
Vocabularies<http://id.loc.gov/>.
More Information
Additional information on this service is available on the LCCN Permalink
FAQ<http://lccn.loc.gov/lccnperm-faq.html>. Specific questions can also be sent to
the Library of Congress through
Ask-A-Librarian<http://www.loc.gov/rr/askalib/ask-digital.html>.
Ann Della Porta
Chief, Integrated Library System Program Office Library of Congress
Washington, DC 20540-4010 [email protected]
