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010 - Library of Congress Control Number (NR)


First Indicator
# - Undefined
Second Indicator
# - Undefined

Subfield Codes
$a - LC control number (NR)
$b - NUCMC control number (R) 
$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. Valid MARC prefixes for LC control numbers are published in MARC 21 Format for Bibliographic Data.
The control number for MARC records distributed by LC is 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$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.



  • Both indicator positions are undefined; each contains a blank (#).


$a - LC control number
Valid LC control number (see explanation of structure of this number given below).
$b - NUCMC control number
Valid entry number for the item being described as found in National Union Catalog of Manuscript Collections (NUCMC). The number begins with the prefix ms.
$z - Canceled/invalid LC control number
Canceled or invalid LC control number, including invalid NUCMC numbers.
$8 - Field link and sequence number
See description of this subfield in Appendix A: Control Subfields.


Classes of LCCNs - LCCNs may be valid, canceled, or invalid (structurally or application) for the record. The following conventions are followed to select the appropriate subfield for an LCCN.
Valid LCCN: - A valid LCCN for a record is the one that appears in the 001 when the record is distributed by LC. It has correct length and structure.
Canceled LCCN: - A record, hence its LCCN, may be canceled for a variety of reasons, very often because it is a duplicate record for the same manifestation of a resource. An LCCN is considered to be canceled when LC designates it as such.
Structurally invalid LCCN: - An LCCN is considered structurally invalid when its length or structure is incorrect according to the practices of the Library of Congress.
Application invalid LCCN: - An LCCN is invalid in application when it appears on the item being cataloged but it is not the LCCN of the record for the item, e.g. the LCCN assigned to the record for one edition is also printed in another, different edition which has its own record and LCCN.
Punctuation - Field 010 does not end in a mark of punctuation. A slash is used to separate revision information from the control number and any suffix. Multiple suffixes are also separated by a slash.
Capitalization - Prefixes are always input as lowercase alphabetic characters. Suffixes and alphabetic identifiers added to the end of the LC control number are input as uppercase alphabetic characters.


The LC control numbering system has had the same basic structure since its initial use to control Library of Congress bibliographic information in card form beginning in 1898 (LCCN structure A). On January 1, 2001, a structural change occurred (LCCN structure B). The basic control number has been fixed in length at 12 characters and will remain that length, although under LCCN structure A suffixes were occasionally used and 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 (1898-2000)
Name of ElementNumber of charactersCharacter position in field
Alphabetic prefix300-02
Serial number605-10
Supplement number111
Suffix and/or Revision Datevariable12-n
LCCN Structure B (2001- )
Name of ElementNumber of charactersCharacter position in field
Alphabetic prefix200-01
Serial number606-11
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.
[LCCN structure A; number on printed card: 68-4897]
[LCCN structure B; number in print form: 2001-45944]
Prior to the existence of MARC records, prefixes of various lengths were used on printed cards with combinations of uppercase or lowercase letters and numbers. For MARC records, equivalents have been defined by the Library of Congress for some of these early prefixes, including those that were longer than two or three characters. All other prefixes are input as found but in lowercase. The first column in the list below gives prefixes found on printed cards not printed from machine-readable records and shows how they are to be input into a MARC version of the record. The list also includes some MARC prefixes not found only on MARC records. Only prefixes which have a MARC form noted below should be recorded in machine-readable records. (The alphabetic prefix for the Library of Congress control number is an authoritative-agency data element, maintained by the Library of Congress.)
Since the prefixes were used in records before 2001, they are found in the LCCN Structure A only.
LCCN Prefix Table
Note: In the first column, an asterisked (*) item indicates the form in which the prefix appears on the card.
Prefix on cardMARC PrefixExplanation of usage
AaCataloging provided to LC by an American library, 1909-
ACacCataloging for foreign materials provided to LC by cooperating libraries under the auspices of the ALA Committee on Cooperative Cataloging, 1932-1942
ACacAnnotated cards for juvenile books, 1966-
AFafCataloging for foreign acquisitions provided to LC by other American libraries, 1946-1950
AFLMaflNo explanation available
AgragrU.S. Department of Agriculture cataloging, 1902-
biHandbook of Latin American Studies record
BRbrLibrary of Congress, Division for the Blind, braille book
BSbsU.S. Bureau of Standards cataloging, 1913-1938
CcU.S. Interstate Commerce Commission cataloging, 1915-1916
CcLibrary of Congress, Chinese entries, 1949-
C-245 or 245*cLC card numbers for June-August 1898; year prefix “98" added when input into MARC
CAcaLC temporary entries for books in the general classified collections, 1905-1937
CA DuplcadLC temporary entries for books in the general classified collections, 1905-1937
CDcdLC analytical entries for sets and series prepared by the Card Division, 1916-1940
CDcdCataloging prepared for LC card sales
clcCollection level cataloging; PREMARC record
CScsCataloging prepared by the LC Cooperative Cataloging and Classification Service, 1934-1939
CXcxCross reference cards used in LC catalogs for Chinese entries, 1958-
cyFederal Cylinder Project, Oct. 1980
1-D-245 or D-245dLC card numbers for May-December 1901; year prefix “01" added when input into MARC
DOdoU.S. Superintendent of Docs. cataloging, 1913-1916
EeU.S. Office of Education cataloging, 1908-1958
ESesU.S. Engineers School cataloging, 1913-1935
FfU.S. Bureau of Fisheries cataloging, 1910-1940
1-F-245 or F-245fLC card numbers for May-December 1901; year prefix “01" added when input into MARC
FifiFilms cataloged by LC, 1951-
FiAfiaCataloging provided by film producers, 1951-
FiEfieCataloging provided by the Visual Education Service of the Office of Education, and other government agencies, 1951-
1-G-245 or G-245*gLC card numbers for May-December 1901; year prefix “01" added when input into MARC
GMgmMaps cataloged by LC, 1968-1972
GSgsU.S. Geological Survey cataloging, 1904-
HhU.S. National Institute of Health cataloging, 1914-1921
HAhaU.S. Housing Authority cataloging, 1940-
HEheHebrew entries cataloged by LC, 1964-
HEWhewU.S. Dept. of Health, Ed., and Welfare cataloging, 1958-
HEXhexCross reference cards used for Hebrew entries, 1964-
1-I-245 or It-245*itLC card numbers for May-December 1901; year prefix “01" added when input into MARC
IntintU.S. Department of the Interior cataloging, 1959
JjLC cataloging for Japanese materials 1949-
JAjaCataloging for Japanese materials provided to LC by other American libraries, 1951
JXjxCross reference cards used for Japanese entries, 1958-
KkKorean entries cataloged by LC, 1951-
KXkxCross reference cards used for Korean entries, 1958-
LlU.S. Dept. of Labor cataloging, 1911-
llhIndex to Hispanic Legislation cataloging
ltfLess-than-full cataloging; PREMARC record
MmSheet music cataloged by LC, 1953-1962
MAmaSheet music for which copy was supplied by another American library, 1953-1961
MapmapAtlases in the Maps Division of LC, 1901-
1-Map-50 or Map-50mapLC card numbers for maps for period May-December 1901; year prefix “01" added when input into MARC
MedmedU.S. Armed Forces Medical Library cataloging, 1946-1948
MicmicMicrofilms cataloged by LC, 1949-
MicAmidMicrofilms for which cataloging was provided by another American library, 1946-
MicpmieMicrocards and microprints cataloged by LC, 1953-
MicpAmifMicrocards and microprints for which cataloging was provided by another American library, 1953-
mmLibrary of Congress Manuscripts Division
mpEarly films cataloged by LC, 1970s
MPAmpaPan American Union cataloging for sheet music, 1956-
MSmsManuscripts cataloged by LC, 1959-
1-Music-245 or Music-245*musLC card numbers for music for May-December 1901; year prefix “01" added when input into MARC
ncnNitrate Film Service cataloging
NEneMaterials published in the Near East or in the languages of those countries, 1961-
NEXnexCross reference cards used for books published in the Near East or in the languages of those countries, 1961-
NOnoU.S. Naval Observatory cataloging, 1930-1940
ntcNational Translation Center cataloging
nucRecords printed in theNational Union Catalogfor which no LC card number is available
orOrder Division cataloging
PApaPan American Union cataloging, 1930-
PhophoCataloging provided by other libraries for photographic reproductions of books, 1927-
PhoMphpCataloging provided by Card Division for photographic facsimiles issued by the Modern Language Association of America, 1927-1938
PhomAphqCataloging provided by other libraries for Modern Language Association of America photographic facsimiles
POpoU.S. Patent Office cataloging, 1917-1953
ppPrints and Photographs videodisc system, March 1984
RrPhonograph records cataloged by LC, 1953-
RAraCataloging provided by other American libraries for phonographs, 1955-
1-Rc-245 or Rc-245*rcLC card numbers for May-December 1901. Year prefix “01" added when input into MARC
reCataloging for commercial ethnic sound recordings produced in the U.S. project, 1981
ruCataloging from the Russian Book Chamber, 1988-
SsSmithsonian Institution cataloging, 1913-
SAsaCataloging for materials published in Southeast Asia or in the languages of those countries, 1961-
SAXsaxCross reference cards used for materials published in Southeast Asia or in the languages of those countries, 1961-
scSerials, CONSER item not in LC
SDsdU.S. Dept. of State cataloging, 1914-
sfSerials form card or Minimal Level Cataloging or classed separately monographic series
SGsgSurgeon General’s Library, U.S. Army cataloging, 1916-
snSerials, CONSER; item may or may not be in LC
suSplit manuscripts records
SSssSocial Security Administration cataloging, 1944-1958
TBtbTalking Books program cataloging
tmpTemporary cataloging from PREMARC
umUnion map; an outside map record input by the Geography and Map Division for NUC use but residing in the G&M database
unkCard for which no LC card number was available; PREMARC
WwDistrict of Columbia Public Library cataloging, 1905-1942
WarwarU.S. Army, War College cataloging, 1907-1932
XxCross reference cards used in LC catalogs, January 1941-
1-Z-245 or Z-245*zLC card numbers for May-December 1901; year prefix “01" added when input into MARC
For control numbers assigned under LCCN structure A, the year portion consists of two digits normally representing the year the record was created. For control numbers assigned under LCCN structure B beginning with the year 2001, 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 for the bibliographic item. During the 1969-1972 period, a 7-series year number was assigned. In these numbers the initial digit of 7 was followed by a modulus-ll check digit. The year in which the card number was assigned can be approximated from the year portion of the Date entered on file (008/00-05). With the re-institution of the year series number in 1972, provisions were made to skip those individual card numbers which could have been assigned previously as a 7-series number. Note: 7-series numbers were not used for non-book map material. The prefix gm was used from 1968 through 1972.
For LC control numbers with two-digit years, the century may be determined according to the following table:
2-digit yearSequential numberCenturySequential numberCentury
98Less than 3000183000 or greater19
99Less than 6000186000 or greater19
00Less than 8000198000 or greater20
Serial number
Serial number portion consists of one to six digits. Serial numbers of less than six digits are right justified and unused positions contain 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 number 85-2 is carried as 85000002 in a record.
Supplement number (LCCN structure A only)
This character position was originally defined to carry a supplement number for dashed-on supplement entries in bibliographic records. Use of the supplement number was not implemented, therefore this position contains a blank. Supplements and similar materials are now cataloged separately by LC and are carried as separate records with their own LC control number. In some older records, information about supplements and similar materials is given in a 500 note field.
Suffix/Alphabetic Identifier (LCCN structure A only)
Older LC control numbers sometimes include suffixes or alphabetic identifiers carried as variable length data following the Supplement number. A single slash (/) introduces the suffix/alphabetic identifier. Multiple occurrences of either suffixes or alphabetic identifiers are separated one from the other by a slash. Suffixes and alphabetic identifiers do not affect the uniqueness of the control number.
All suffixes and alphabetic identifiers, except the revision date, appear in the MARC record as uppercase alphabetic characters. On printed card copy, suffixes appear after the LC control number separated by a slash. Suffixes have not been assigned since 1969 and they will be deleted from Library of Congress files in 1999. Alphabetic identifiers appear on printed card copy as uppercase alphabetic characters beneath the LC card number in the lower right hand corner of the card. Alphabetic identifiers were first assigned in 1969 and were used as distribution information for card copy by LC. Alphabetic identifiers will be deleted from the Library of Congress files in 1999.
[Printed number is 79-139101 with AC MN printed below the number.]
[Printed number is 65-77628 with MN printed below the number.]
Suffix/alphabetic identifiers
ACused on records included in the "Annotated Card" program
AMused for works in Amharic
ACNused for works in Chinese
AJused for works in Japanese
AKused for works in Korean
Fused for records created by the Audiovisual Section, Special Materials Cataloging Division for motion pictures, filmstrips, sets of slides and transparencies, video recordings, etc.
HEused for works published in the Hebrew alphabet, regardless of language
Mused for works classed in M
MAPused for atlases
MNused for works classed in ML and MT
MPused for records created by the Motion Picture, Broadcasting and Recorded Sound Division
NEused for works in Armenian, Arabic, Georgian, Ottoman Turkish, Persian, Pashto, and Turkish, as well as any non-Slavic language of Central Asia written in the Cyrillic alphabet
PPused for records created by the Prints and Photographs Division
Rused for all sound recordings
Revision Date (LCCN structure A only)
Revision dates associated with LC control numbers specify the latest date that the bibliographic data in a record underwent a change. Revision data do not affect the uniqueness of the control number. To account for the number of times significant changes have been made to a record beyond the first such change, a number was added as the last character of the revision date. The date a record was originally created is the Date entered on file (field 008/00-05).
A revision date such as “r73" means that the record was changed in 1973. The revision date “r743" means that significant changes have been made to the record three times, the last being made in 1974.
[Number 75-425165 revised in 1975.]
[Number 73-2284 with (r75)rev 2 printed revision information.]
[Printed number is 58-62665 rev*. (The * was represented on the printed product by a double dagger and indicated limited cataloging; it was carried in the MARC record as an L. When the LC control number was printed from the MARC record, the L printed as Lim beneath the control number.)]
Revision date was used as an indication of the degree of importance of a change made to a record. A significant change to a record at the Library of Congress was defined as one important enough to warrant, among other things, redistribution of cards to LC's own catalogs. A significant change included changes to content designation, to an access point (fields 020, $a or $z, 028, $a, 050, 051, 082, 1XX, 240, 245$a, 4XX (excluding 490), 6XX, 7XX, 8XX), a change to the extent of an item (300$a), a change to the publication date (260$c), a change to the record control number (field 001), or a change to Leader/18 (Descriptive cataloging form).
Revision information was separated from a suffix or an alphabetic identifier by one slash (/). If no suffixes or alphabetic identifiers are present, revision information was separated from the Supplement number by two slashes (//). The inclusion of revision data was discontinued in 1999 and will be deleted from all records in the Library of Congress files.

  • This article is a Stub. It will be expanded to achieve the level of a proper encyclopedia article. 

  1. Library of Congress. (accessed October 10, 2017)



  • Written: 2017-10-12


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