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DATE: Dec. 15, 2006

NAME: Definition of Field 004 (Control Number for Related Bibliographic Record) in the MARC 21 Bibliographic Format


SUMMARY: This paper discusses the addition of field 004 to link one bibliographic record to another in the same system. It would be similar to the same field in the holdings format that links a holdings record to a bibliographic record.

KEYWORDS: Field 004 (BD), Control Number for Related Bibliographic Record (BD)



12/15/2006 - Made available to the MARC community for discussion.

01/20/2007 - Results of the MARC Advisory Committee discussion - The group agreed that defining a method to link one bibliographic record to another in the same system is advantageous. However, because the group thought of several other ways that this link may work (for example, linking to an outside system), it decided that a new discussion paper should be written that explores the larger issues involved in linking records for consortial and private library uses.

Definition of Field 004 in the MARC 21 Bibliographic Format


OCLC is implementing changes to their system that will allow for linking separate bibliographic records to the master record as part of the process to integrate RLIN records into its database. There is a need to store the control number of the master record to which an institution record is linked. The master record is a composite record with data contributed from many sources or institutions. It is the same kind of bibliographic record that one sees in WorldCat today. Currently there is not an appropriate place in the MARC bibliographic format for this inter-system linking between bibliographic records.


2.1. Institution records vs. master records.

Institution records are the records that each library creates. Each library may create its own record or records with its local data, embedded holdings, etc., and link them to the master record to facilitate retrieval, search navigation, and record matching in union

It is intended that institution records will get linked to master records in one of two ways. The cataloger will select a master record and create a copy of it as an institution record. The cataloger can then modify the institution record. The amount of data remaining from the master record is solely at the discretion of the cataloger. Moreover, the institution record will be a complete record that can stand alone in any system but is linked to the master record in OCLC's system.

The other way in which an institution record is linked to a master record is through batch processing. Records will be processed through the usual process. Instead of only adding a location symbol to the master record when a match is found, OCLC will add a location symbol and an institution record if the library's profile indicates that this should be done. The institution record is the library's bibliographic record.

2.2. Addition of 004 for linking to another bibliographic record

There are a number of fields in the format for record control numbers to link to other records in systems. The following is a list of them and their intended use:

There is not a field that links to another bibliographic record in the same system.

The MARC 21 Holdings Format includes a field 004 (Control Number for Related Bibliographic Record), which allows for linking the holdings record to a bibliographic record in the same system. A field 004 could be defined in the bibliographic format for a similar type of linking, but to relate one bibliographic record to another. It would not be appropriate to use the linking entry fields, because the relationship indicated by use of linking entry fields is the relationship between the resource described in the record and another related resource, not the relationship between records.

Field 004 could be defined as follows:

  Field 004 contains a system control number for a related bibliographic record in the same system as that in field 001. This field links together separate records for the same bibliographic resource.


  1. Would other institutions find the ability to link bibliographic records useful (i.e. different records for the same resource rather than linking records for different resources, which is already possible)?
  2. Is there a reason why this field needs to be communicated rather than using a local field?
  3. If 004 is used in other systems, will there need to be a way to identify the institution whose control number it is? If so, would it be included as text in the field? Note that the control fields have no subfields.
  4. How might the field be defined so that systems other than OCLC can use it? Would a variable field with subfields be preferable?
  5. Will the master record link to individual records, and if so, using the same field?
  6. How would this field relate to the control numbers in field 035? Could the same number be in both?

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