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BLvl:  Bibliographic Level

Record Type



ALL: Leader/07

Input Standards

BKS, COM, MAP, MIX, REC, SCO, VIS: Mandatory. One-character code. Default: m

CNR: Mandatory. One-character code. Default: s


ALL, 006

Code indicating the bibliographic level of the record, i.e., mode of issuance, relationship of component part, etc.


Appropriate Type and BLvl combinations. All codes are valid for all formats except BKS and CNR; however, not every code is appropriate for every type of material. The online system does not allow incorrect combinations of Type and BLvl, for example, Type code d and BLvl codes b or s; Type code p and BLvl codes m or a. See Type for more information.



Monographic component part. Monographic bibliographic unit that is physically attached to or contained in another unit such that the retrieval of the component part is dependent on the identification and location of the host item or container. Contains fields that describe the component part and data that identify the host in field 773.

Examples of monographic component parts with corresponding host items include an article in a single issue of a periodical, a chapter in a book, a track on an audio disc, and a map on a single sheet that contains several maps.

BLvl     a
100 1  
Keefer, Louis E.
245 1 Joint development at transit stations in the United States / ǂc Louis E. Keefer
300     pages 333-342 ; ǂc 24 cm
773 0   ǂt Transportation. ǂg Volume 12, number 4 (May 1985) ǂx 0049-4488 ǂw (DLC)   72624409 ǂw (OCoLC)1624097

Serial component part. A component (i.e., a bibliographic unit physically contained in another bibliographic unit) that is itself a serial. See the definition of a serial under code s. Identify the host item in field 773 so that the component may be located. An example of a serial component part with corresponding host item is a regularly appearing column or feature in a periodical.

BLvl     b
Business directory of Trenton and vicinity
300     parts ; ǂc 46-54 cm
310     Triweekly
362 1   Began with August 12, 1844; ceased April 4, 1845
773 0  
ǂt Sheet anchor of democracy. ǂg August 12, 1844-April 4, 1845 ǂw (DLC)sn 84020602 ǂw (OCoLC)11219947

Collection. A made-up multipart group of items that were not originally published, distributed or produced together. The record describes units defined by common provenance or administrative convenience for which the record is intended as the most comprehensive in the system.

BLvl     c
110 2
Wyandotte Chemicals Corporation
ǂk Records, ǂf 1898-approximately 1979
300     5 linear ft.

Subunit. A component of an archival unit described collectively elsewhere. A subunit may be folders, boxes, series, subgroups, or subcollections. Identify the archival unit in field 773 so that the component may be located.

BLvl     d
110 2  
American Medical Association. ǂb Department of Investigation
245 0 0 Records. ǂp Physical culture magazine, ǂf 1908-1961
300     1.6 cubic ft. (5 boxes)
773 0   American Medical Association. Department of Investigation. ǂt Records, 1843-1990 (bulk 1906-1975) ǂw (OCoLC)19248517

Integrating resource. A bibliographic resource that is added to or changed by means of updates that do not remain discrete and are integrated into the whole. Integrating resources may be finite or continuing. Examples include updating loose-leaf publications, updating databases, and updating Web sites.

BLvl     i
Musica : ǂb the international database of choral music repertoire ...
264   1
Strasbourg, France : ǂb Musica International
300     1 online resource
362 1   Began in 1996?

Monograph/Item. A monograph is a nonserial item that is either complete in one part or complete or intended to be completed in a finite number of separate parts. Examples include a multi-volume monograph or a sound recording with multiple tracks.

BLvl     m
100 1
Clancy, Tom, ǂd 1947-2013
245 1
The hunt for Red October / ǂc Tom Clancy
264   1
Annapolis, Maryland : ǂb Naval Institute Press, ǂc [1984]
387 pages ; ǂc 24 cm

Serial. A resource issued in successive parts, usually having numbering, that has no predetermined conclusion. Serials include periodicals; newspapers; annuals (reports, yearbooks, etc.); the journals, memoirs, proceedings and transactions of societies; and monographic series. Serials are not published items containing collections of works.

BLvl     s
245 0 0
Architectural digest
264   1
Los Angeles : ǂb John C. Brasfield Publishing Corporation
300     volumes : ǂb illustrations ; ǂc 28-35 cm
362 1   Began with Volume 1, published in 1925


For indexing and searching information, see Searching WorldCat Indexes, Leader/07.


For more information, including content designator history, see MARC 21 Format for Bibliographic Data, Leader/07.

This page last revised: November 11, 2020