# - Undefined
# - Undefined
|$a - LC control number (NR)
$z - Canceled/invalid LC control number (R)
|$8 - Field link and sequence number (R)
Unique number assigned to a MARC record by the Library of Congress.
The control number for MARC records distributed by LC is referred to as an LC control number (LCCN).
The LC control number is carried in field 001 (Control Number) in records distributed by LC's Cataloging Distribution Service and in field 010 subfield $a. An organization using LC records may remove the LC control number from field 001 and use field 001 for its own system control number.
An LC record may contain field 010 with a canceled or invalid control number of a previously-distributed record. A record may be canceled because it is a duplicate record for the same item. The structure of the canceled/invalid control number is the same as that used by LC in field 001.
The basic control number has been fixed in length at 12 characters used. The prefix, year, and serial number are the basic elements required to make an LCCN unique.
|Name of Element||Number of characters||Character position in field|
Alphabetic prefix - Prefixes are carried in a MARC record as lowercase alphabetic characters and serve to differentiate between different series of LC control numbers. Prefixes are left justified and unused positions contain blanks. If no prefix is present, the prefix portion contains blanks.
Year - For control numbers assigned under the LCCN structure, the year portion consists of four digits. In most numbers, the year portion reflects the year in which the LC control number was assigned to the record.
Serial number - The serial number portion consists of one to six digits. Serial numbers of less than six digits are right justified and unused positions contains zeros. The hyphen which separates the year and the serial number on LC printed products is not carried in the MARC record. For example, the serial number 2001-2 would be carried as 2001000002 in a record.