First and Second indicators:

#  Undefined


a  LC control number (NR)

b  NUCMC control number  [Not applicable]

z  Canceled/invalid LC control number (R)

8  Field link and sequence number (R)

NOTE:  See MARC 21 Format for Bibliographic Data (010 Library of Congress Control Number) for code definitions not given below.


The LIBRARY OF CONGRESS CONTROL NUMBER is the unique number assigned to an authenticated CONSER record.  It is used to manage the processing of the record at the Library of Congress and is the control number under which the record is distributed by the CDS MARC Distribution Service.

The LC control number (LCCN) is input, displayed, and output by OCLC to LC in field 010 (subfield $a).  The LCCN is distributed by LC in both fields 010 and 001.  LC control numbers are assigned by all CONSER members to records that are originally input, to existing records that were not previously authenticated, and in some cases, to previously authenticated records.

Beginning in 2001, newly assigned LCCNs include a four-digit number representing the year of assignment.  LCCNs assigned previously, from 1898 to 2000, had a two-digit year portion.  Making room for the four-digit year also required changing other portions of the machine-readable LCCN structure, as defined by the MARC 21 Format for Bibliographic Data.  Both formats are valid and are used in CONSER records, as they were originally assigned.  Earlier forms of LCCN found in printed sources are also still valid for retrospective input.  (For instructions, see Appendix P.)

The form required for field 010 input and used for field 010 display of the LCCN (in either format) on the OCLC system is not identical to the MARC-defined LCCN structure or to the form input for LCCN in record control number subfields of linking entry fields.  (For details of the LC control number's structures and their history, see Appendix P.  For instructions on inputting LCCNs in linking entry fields, see Linking Entry Fields--General Information.)

Regular LC control numbers

Beginning in 2000, regular LC control numbers (i.e., unprefixed numbers) are assigned by the Library of Congress and CONSER members to newly input records or first-time authenticated records.  Prior to May 1999, regular LCCNs were also assigned by LC catalogers to previously authenticated CONSER records that had "pseudo" control numbers.  The unprefixed LCCN in field 010 in OCLC consists of a year portion (four-digit or two-digit, as assigned), then a hyphen, and then a consecutively assigned number of one to six digits in length.  (If the consecutively assigned number is less than six digits long, there is no need to input leading zeroes before the number.  If leading zeroes are input, the OCLC system deletes them from the display.)

010 ## 85-645325

010 ## 68-4897

010 ## 2001-239001

010 ## 2001-3292


LC control numbers on records for works cataloged prior to Dec. 1, 1968 may be preceded by alphabetic prefixes.  These prefixes can be from one to three characters in length, and are carried in the machine record as lowercase alphabetic characters.  In field 010 on the OCLC system, the prefix is input directly preceding the year portion of the LCCN, with no spaces between them.  For a complete list of prefixes, see Appendix P.

010 ## a62-2407

010 ## agr17-1177

010 ## ca35-621

010 ## map68-359

Pseudo LC control numbers

Numbers structured like LC control numbers, and identified by a "pseudo" prefix, are used in CONSER records for which no regular LC control number exists at the time of authentication.  The pseudo LC control numbers usually have their own sequential numbering scheme, i.e., the prefix is a significant part of the numbering inasmuch as the numeric portion may also be valid for other prefixed LC control numbers as well as unprefixed LC control numbers.  Input pseudo LCCN prefixes in the same way as other prefixes, as described above.

"sc" prefix.

Used prior to 2000 for records authenticated by LC for titles not held by LC or not cataloged by LC as represented by the record.  If a title is subsequently received by LC, the "sc" number is canceled in favor of a regular control number.

010 ## sc85-106

"sf" prefix.

Used prior to 2000 by LC in originally input or first-time authenticated records when a title is held by LC and given less than full cataloging.  This included form card cataloging, minimal level cataloging, and other forms of cataloging for which no printed card exists.  Prior to May 1999, LC also assigned "sf"-prefixed LCCNs when giving less than full cataloging to previously authenticated CONSER records.

All records containing an "sf"-prefixed control number also have an 050 field.  The information in the field varies.

010 ## sf76-208

050 00 TC1 $b .S45

010 ## sf77-8


010 ## sf93-91310

050 00 WMLC 93/922

010 ## sf85-9857

050 00 Microfilm 85249

"sn" prefix.

Used prior to 2000 in records initially authenticated by NSDP and CONSER members.  (Prior to 1984, "sn" control numbers were also assigned to LC minimal level cataloging records.)  "sn"-prefixed numbers are currently assigned only for LC newspaper cataloging and USNP records.

010 ## sn82-9563

010 ## sn99-1

010 ## sn2001-58302

LAC control numbers

For Library and Archives Canada records batchloaded to OCLC with a 001, OCLC derives a "dummy" LC control number from the Canadian serial number in the 001 field, unless an LC control number is already present in field 010.

For LAC records input online, LAC inputs a pseudo control number unless an LC control number is present.  The pseudo control number carries, respectively, a "ce" or "cf" prefix for the English and French catalog records, for a bilingual publication.  For the single record for a unilingual publication, the prefix "cn" is used.  The "cn", "ce", and "cf" numbers for online records are taken from one sequence of numbers.

NOTE:  If a regular LC control number exists for an English bilingual record, LAC will input the LC control number in subfield $a of field 010 and will input a pseudo control number, preceded by the prefix "ce", in 010, subfield $z.  In the French bilingual record, LAC will input the same pseudo control number, but preceded by the prefix "cf", in subfield $a of field 010.  These procedures enable LAC to match the English and French bilingual publications.

"ce" prefix.

Canadian bilingual publication, English language cataloging

"cf" prefix.

Canadian bilingual publication, French language cataloging

(The same number is used for English and French bilingual publications; the prefixes differentiate the two records.)

010 ## ce76-73468

010 ## cf76-73468

010 ## ce2001-790000

"cn" prefix.

Unilingual Canadian publication, English or French language cataloging

010 ## cn76-83077

010 ## cn2001-390000

Suffixes, Alphabetic Identifiers, and Revision Dates

Prior to January 1999, suffixes, alphabetic identifiers, and revision dates were input at the ends of some LC control numbers.  These elements did not affect the uniqueness of the LCCN.  They may be encountered during retrospective conversion following LCCNs in printed sources.  For examples and information on their former usage, see Appendix P.

Do not input suffixes, alphabetic identifiers, or revision dates in field 010.  The inclusion of these elements was discontinued in 1999.  They have been stripped from records in the LC database and the OCLC database.


$a   LC control number.

The subfield $a contains the valid control number in one of the forms described above.  This portion of the 010 field doubles as the CONSER database's control number and is also converted to field 001 prior to a record's distribution within the CONSER database.

The critical role of the $a as control number dictates that it be accurately input.  To avoid possible duplication, the number should be searched on the OCLC system before the record is updated.  It is also advisable to add the number to the record as the last step before updating the record.  Once a record has been updated (i.e., added or replaced) through the authentication process, institutions other than LC should not change the $a portion of field 010 – even to correct a typographical error – without first sending a "delete" status record to LC (see C2.2.2.) for the incorrect number or contacting LC to make the change for them.

The subfield $a in an authenticated record must be a valid control number, i.e., one assigned or verified by the authenticating agency.

Catalogers should use an existing LCCN in an OCLC record if they can verify it against the LC Online Catalog.

010 ## 10026545

If the record is found in the LC catalog (as a non-CONSER record) (e.g., a PREMARC or SERLOC record), the cataloger should use the LCCN and also transcribe the LC call number (050 00).

010 ## ca 32000286

050 00 AY838.C7 $b A35

As long as the cataloger uses the LC LCCN (010) and LC call number (050 00) when authenticating the record, there is no need to report their authentication to LC.  The record will not overlay the LC ILS record because the LC record will not have the required 035 OCLC control number match point.  The record will, however, be written to a file where it can be reviewed and updated by LC before being merged into the LC ILS.  It also gives LC the opportunity to add "DLC" holdings and additional LC data to the OCLC record.

An unverified existing LCCN number can be retained in subfield $z if it meets any of the criteria listed below.  In that case, move the unverified LCCN to subfield $z and add a new control number is added to the subfield $a.  If/when the number in subfield $z is verified as correct, it will be restored to the subfield $a; the control number supplied by the authenticating institution will be placed in subfield $z.  If incorrect, it will be deleted from the record.

$z   Canceled/invalid/unverified LC control number.

Subfield $z is used for:

1.   Canceled LCCNs:  Prior to 2000, if an authenticated CONSER record contained a pseudo LC control number and LC later acquired and cataloged the title, LC added a new control number to subfield $a and moved the CONSER pseudo control number to subfield $z.  LC control numbers are also recorded in $z when records are collapsed or duplicate records are canceled.

Canceled LCCNs from monographic records canceled by LC are also included in field 010 subfield $z, recorded after canceled LCCN(s) from serial records.  It is preferable for canceled LCCNs to be input in numeric order, particularly when recording several canceled numbers on a single record.

2.   Invalid LCCNs:  If any CONSER or OCLC participant has input an erroneous number in subfield $a, the erroneous number is canceled by LC or LAC and moved to subfield $z.  The correct number is input in subfield $a.

3.   Unverified LCCNs [CONSER practice]:  If an unverified control number exists in the record at the time the record is newly authenticated, search the LCCN in OCLC to be sure that it has not been applied to a monograph or an earlier/later title of a serial.  If the LCCN has been used for another title, do not record the LCCN anywhere in the record.  If a record is not found, the cataloger should move the suspect control number to $z and add a valid number to subfield $a.  This process should also be applied to LCCNs supplied by LC field offices, printed on issues, but otherwise unverified by an LC authenticated record.  For new input, use the cataloging institution's own symbol in 040 $a in this case.

NOTE:  When moving an LC control number to 010 subfield $z, input it there in the format used when it was assigned.  Therefore, the same record may have an LCCN with four-digit year in subfield $a and one (or more) with two-digit year in subfield(s) $z.  Prefixes should be retained.  Any suffixes, alphabetic identifiers, and revision data, however, should be dropped.

Subfield $z is not used for:

1.   The LCCN on LC's printed card cataloging when the type of cataloging differs from the online record (e.g., the online record is a successive entry record; LC's printed card reflects latest entry cataloging).

2.   Control numbers input in field 010 of an unauthenticated record by a CONSER member or OCLC institution that prove to be in error when LC authenticates the record.

Related fields, etc.

C1, C2, 001, 016, Appendix P

010 Library of Congress Control Number  (MARC 21 Format for Bibliographic Data)

See also:

01X-09X  Numbers and Codes

Variable Data Fields

Section E.  MARC 21 Format for Serials as Applied Within CONSER

CONSER Editing Guide:  Contents