| First Indicator Undefined # - Undefined |
Second Indicator Undefined # - 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.
| 010 | ##$a###85153773# | ||||||||
| 010 | ##$anuc76039265# | ||||||||
| 010 | ##$a##2001627090 | ||||||||
| 010 | ##$a##2001336783 | ||||||||
| 010 | ##$a###89798632#$bms#89001579# | ||||||||
| 010 | ##$a###76647633#$zsc#76000587# | ||||||||
| 010 | ##$a###81691938#$z###82692384# | ||||||||
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 Element | Number of characters | Character position in field |
| Alphabetic prefix | 3 | 00-02 |
| Year | 2 | 03-04 |
| Serial number | 6 | 05-10 |
| Supplement number | 1 | 11 |
| Suffix and/or Revision Date | variable | 12-n |
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 | ##$a###68004897# [LCCN structure A; number on printed card: 68-4897] |
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| 010 | ##$a##2001045944 [LCCN structure B; number in print form: 2001-45944] |
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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.
Note: In the first column, an asterisked (*) item indicates the form in which the prefix appears on the card.
| Prefix on card | MARC Prefix | Explanation of usage |
| A | a | Cataloging provided to LC by an American library, 1909- |
| AC | ac | Cataloging for foreign materials provided to LC by cooperating libraries under the auspices of the ALA Committee on Cooperative Cataloging, 1932-1942 |
| AC | ac | Annotated cards for juvenile books, 1966- |
| AF | af | Cataloging for foreign acquisitions provided to LC by other American libraries, 1946-1950 |
| AFLM | afl | No explanation available |
| Agr | agr | U.S. Department of Agriculture cataloging, 1902- |
| bi | Handbook of Latin American Studies record | |
| BR | br | Library of Congress, Division for the Blind, braille book |
| BS | bs | U.S. Bureau of Standards cataloging, 1913-1938 |
| C | c | U.S. Interstate Commerce Commission cataloging, 1915-1916 |
| C | c | Library of Congress, Chinese entries, 1949- |
| C-245 or 245* | c | LC card numbers for June-August 1898; year prefix “98" added when input into MARC |
| CA | ca | LC temporary entries for books in the general classified collections, 1905-1937 |
| CA Dupl | cad | LC temporary entries for books in the general classified collections, 1905-1937 |
| CD | cd | LC analytical entries for sets and series prepared by the Card Division, 1916-1940 |
| CD | cd | Cataloging prepared for LC card sales |
| clc | Collection level cataloging; PREMARC record | |
| CS | cs | Cataloging prepared by the LC Cooperative Cataloging and Classification Service, 1934-1939 |
| CX | cx | Cross reference cards used in LC catalogs for Chinese entries, 1958- |
| cy | Federal Cylinder Project, Oct. 1980 | |
| 1-D-245 or D-245 | d | LC card numbers for May-December 1901; year prefix “01" added when input into MARC |
| DO | do | U.S. Superintendent of Docs. cataloging, 1913-1916 |
| E | e | U.S. Office of Education cataloging, 1908-1958 |
| ES | es | U.S. Engineers School cataloging, 1913-1935 |
| F | f | U.S. Bureau of Fisheries cataloging, 1910-1940 |
| 1-F-245 or F-245 | f | LC card numbers for May-December 1901; year prefix “01" added when input into MARC |
| Fi | fi | Films cataloged by LC, 1951- |
| FiA | fia | Cataloging provided by film producers, 1951- |
| FiE | fie | Cataloging provided by the Visual Education Service of the Office of Education, and other government agencies, 1951- |
| 1-G-245 or G-245* | g | LC card numbers for May-December 1901; year prefix “01" added when input into MARC |
| GM | gm | Maps cataloged by LC, 1968-1972 |
| GS | gs | U.S. Geological Survey cataloging, 1904- |
| H | h | U.S. National Institute of Health cataloging, 1914-1921 |
| HA | ha | U.S. Housing Authority cataloging, 1940- |
| HE | he | Hebrew entries cataloged by LC, 1964- |
| HEW | hew | U.S. Dept. of Health, Ed., and Welfare cataloging, 1958- |
| HEX | hex | Cross reference cards used for Hebrew entries, 1964- |
| 1-I-245 or It-245* | it | LC card numbers for May-December 1901; year prefix “01" added when input into MARC |
| Int | int | U.S. Department of the Interior cataloging, 1959 |
| J | j | LC cataloging for Japanese materials 1949- |
| JA | ja | Cataloging for Japanese materials provided to LC by other American libraries, 1951 |
| JX | jx | Cross reference cards used for Japanese entries, 1958- |
| K | k | Korean entries cataloged by LC, 1951- |
| KX | kx | Cross reference cards used for Korean entries, 1958- |
| L | l | U.S. Dept. of Labor cataloging, 1911- |
| llh | Index to Hispanic Legislation cataloging | |
| ltf | Less-than-full cataloging; PREMARC record | |
| M | m | Sheet music cataloged by LC, 1953-1962 |
| MA | ma | Sheet music for which copy was supplied by another American library, 1953-1961 |
| Map | map | Atlases in the Maps Division of LC, 1901- |
| 1-Map-50 or Map-50 | map | LC card numbers for maps for period May-December 1901; year prefix “01" added when input into MARC |
| Med | med | U.S. Armed Forces Medical Library cataloging, 1946-1948 |
| Mic | mic | Microfilms cataloged by LC, 1949- |
| MicA | mid | Microfilms for which cataloging was provided by another American library, 1946- |
| Micp | mie | Microcards and microprints cataloged by LC, 1953- |
| MicpA | mif | Microcards and microprints for which cataloging was provided by another American library, 1953- |
| mm | Library of Congress Manuscripts Division | |
| mp | Early films cataloged by LC, 1970s | |
| MPA | mpa | Pan American Union cataloging for sheet music, 1956- |
| MS | ms | Manuscripts cataloged by LC, 1959- |
| 1-Music-245 or Music-245* | mus | LC card numbers for music for May-December 1901; year prefix “01" added when input into MARC |
| ncn | Nitrate Film Service cataloging | |
| NE | ne | Materials published in the Near East or in the languages of those countries, 1961- |
| NEX | nex | Cross reference cards used for books published in the Near East or in the languages of those countries, 1961- |
| NO | no | U.S. Naval Observatory cataloging, 1930-1940 |
| ntc | National Translation Center cataloging | |
| nuc | Records printed in theNational Union Catalogfor which no LC card number is available | |
| or | Order Division cataloging | |
| PA | pa | Pan American Union cataloging, 1930- |
| Pho | pho | Cataloging provided by other libraries for photographic reproductions of books, 1927- |
| PhoM | php | Cataloging provided by Card Division for photographic facsimiles issued by the Modern Language Association of America, 1927-1938 |
| PhomA | phq | Cataloging provided by other libraries for Modern Language Association of America photographic facsimiles |
| PO | po | U.S. Patent Office cataloging, 1917-1953 |
| pp | Prints and Photographs videodisc system, March 1984 | |
| R | r | Phonograph records cataloged by LC, 1953- |
| RA | ra | Cataloging provided by other American libraries for phonographs, 1955- |
| 1-Rc-245 or Rc-245* | rc | LC card numbers for May-December 1901. Year prefix “01" added when input into MARC |
| re | Cataloging for commercial ethnic sound recordings produced in the U.S. project, 1981 | |
| ru | Cataloging from the Russian Book Chamber, 1988- | |
| S | s | Smithsonian Institution cataloging, 1913- |
| SA | sa | Cataloging for materials published in Southeast Asia or in the languages of those countries, 1961- |
| SAX | sax | Cross reference cards used for materials published in Southeast Asia or in the languages of those countries, 1961- |
| sc | Serials, CONSER item not in LC | |
| SD | sd | U.S. Dept. of State cataloging, 1914- |
| sf | Serials form card or Minimal Level Cataloging or classed separately monographic series | |
| SG | sg | Surgeon General’s Library, U.S. Army cataloging, 1916- |
| sn | Serials, CONSER; item may or may not be in LC | |
| su | Split manuscripts records | |
| SS | ss | Social Security Administration cataloging, 1944-1958 |
| TB | tb | Talking Books program cataloging |
| tmp | Temporary cataloging from PREMARC | |
| um | Union map; an outside map record input by the Geography and Map Division for NUC use but residing in the G&M database | |
| unk | Card for which no LC card number was available; PREMARC | |
| W | w | District of Columbia Public Library cataloging, 1905-1942 |
| War | war | U.S. Army, War College cataloging, 1907-1932 |
| X | x | Cross reference cards used in LC catalogs, January 1941- |
| 1-Z-245 or Z-245* | z | LC card numbers for May-December 1901; year prefix “01" added when input into MARC |
Year
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 year | Sequential number | Century | Sequential number | Century |
| 98 | Less than 3000 | 18 | 3000 or greater | 19 |
| 99 | Less than 6000 | 18 | 6000 or greater | 19 |
| 00 | Less than 8000 | 19 | 8000 or greater | 20 |
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.
| 010 | ##$a###79139101#/AC/MN [Printed number is 79-139101 with AC MN printed below the number.] |
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| 010 | ##$a###65077628#/MN [Printed number is 65-77628 with MN printed below the number.] |
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| Suffix/alphabetic identifiers | |
| AC | used on records included in the "Annotated Card" program |
| AM | used for works in Amharic |
| ACN | used for works in Chinese |
| AJ | used for works in Japanese |
| AK | used for works in Korean |
| F | used for records created by the Audiovisual Section, Special Materials Cataloging Division for motion pictures, filmstrips, sets of slides and transparencies, video recordings, etc. |
| HE | used for works published in the Hebrew alphabet, regardless of language |
| M | used for works classed in M |
| MAP | used for atlases |
| MN | used for works classed in ML and MT |
| MP | used for records created by the Motion Picture, Broadcasting and Recorded Sound Division |
| NE | used 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 |
| PP | used for records created by the Prints and Photographs Division |
| R | used 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.
| 010 | ##$a###75425165#//r75 [Number 75-425165 revised in 1975.] |
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| 010 | ##$a###73002284#//r752 [Number 73-2284 with (r75)rev 2 printed revision information.] |
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| 010 | ##$a###58062665#/L/r58 [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.)] |
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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.
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