Library of Congress >> MARC >> Classification >> 01X-084 >> 010

010 - Library of Congress Control Number (NR)

MARC 21 Classification - Full
January 2000

First Indicator
# - Undefined

Second Indicator
# - Undefined

Subfield Codes
$a - LC control number (NR)
$z - Canceled/invalid LC control number (R)
$8 - Field link and sequence number (R)


Unique number assigned to a classification record by the Library of Congress.

LC control number is carried in field 001 (Control Number) in records distributed by LC's Cataloging Distribution Service. It may also be carried in field 010$a.

A 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 and represents the same classification data represented by another record. The structure of the canceled or invalid control number is the same as that used by LC in field 001. Field 010 may or may not contain a subfield $a with the valid control number from the 001 field.




$a - LC control number
Valid LC control number (see explanation of structure of this number given below).
010 ##$acf#90000001#
$z - Canceled/invalid LC control number
Includes invalid NUCMC numbers.
010 ##$acf#80022124#$zcf#80014241#
$8 - Field link and sequence number
See the description of this subfield in Appendix A: Control Subfields.


Agency Information - Field 010 is an agency-assigned field; it may be used only for an LC control number.
Punctuation - Field 010 does not end in a mark of punctuation.
Capitalization - Prefixes are always input as lowercase alphabetic characters.


The LC control numbering system used with classification records has the same basic structure as that used in control numbers for Library of Congress bibliographic (LCCN structure A), authority, and holdings data records. On January 1, 2001, a structural change will occur (LCCN structure B). The basic control number has been fixed in length at 12 characters and will remain that length. Under LCCN structure B the location of element parts is slightly altered to accommodate a four digit year. Under both structures, the prefix, year, and serial number are the basic elements required to make an LCCN unique.

LCCN Structure A (1978-2000)

Name of Element Number of characters Character position in field
Alphabetic prefix 3 00-02
Year 2 03-04
Serial number 6 05-10

LCCN Structure B (2001- )

Name of Element Number of characters Character position in field
Alphabetic prefix 2 00-01
Year 4 02-05
Serial number 6 06-11

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.

010 ##$acf#97051955#
[LCCN structure A; cf97-51955]
010 ##$acf2001050268
[LCCN structure B; cf2001-50268]

Year - For control numbers assigned under LCCN structure A, the year portion consists of two digits representing the year the control number was assigned. For control numbers assigned under the LCCN structure B beginning with the year 2001, the year portion consists of four digits.

Serial number - The serial number portion consists of one to six digits. Serial numbers of less than six digits are right justified and each unused position contains a zero. The hyphen separating the year and the serial number in LC printed products is not carried in the MARC record. For example, the serial number in control number 85-2 is carried as 85000002.

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