Question: What does an authority record's 010 field contain?
The 010 field contains a number called the Library of Congress Control Number (LCCN). Each authority record distributed by the Library of Congress is assigned an LCCN. It provides a unique identifier that can be used by all systems. When our Systems Office loads authority records into Orbis, the LCCN serves as the match point for record overlays.
Although the Library of Congress is the distributor for these authority records, many of the records are actually created by catalogers at other libraries. These libraries contribute authority records to LC through the Name Authorities Cooperative Program (NACO). Yale is a participant in the NACO program.
NACO participants generally contribute authority records to LC using either RLIN or OCLC. If you look carefully at the LCCN in an authority record, you can identify where the record was originally created simply by looking at the number's alphabetic prefix:
n = Library of Congress created the record
nr = NACO participant created the record in RLIN
no = NACO participant created the record in OCLC
nb = NACO participant at the British Library created the record
sh = Library of Congress subject heading
So, an authority record with an LCCN in the form "nb2003012487" means
the record was contributed through NACO by the British Library. The next four digits mean the record was created in the year 2003.
Sometimes the 010 field will have two LCCNs, one in subfield $a and one in subfield $z. This means that at some point in the past, duplicate authority records were discovered and one of them was deleted. The LCCN from the deleted authority record was coded subfield $z and added to the LCCN of the authority record that was kept.
Finally, you will sometimes come across an authority record in Orbis WITHOUT an 010 field. This is a "locally created" authority record. Before the Library was a member of the NACO program, Yale catalogers only created authority records in our local catalog and did not share them with other libraries. These "locally-created" authority records will always have an 035 field containing a NOTIS system number that begins with the letter "Y".
As NACO catalogers encounter these locally-created authority records in Orbis, they are supposed to recreate them as NACO records and then delete the locally-created authority records. In time, we hope to eliminate all of the locally-created authority records that currently exist in Orbis.