The record-linking technique in MARC is described below.

Linking Entry Fields (fields 760-787) -- These fields carry descriptive data concerning the related item, the control number for the record of the related item, or both.  Minimal content designation is provided for the data concerning the related item that is used in the linking entry fields.  For data operations requiring fuller content designation such as indexing and sorting, subfield $w (Control number for the related item) allows the system to follow that link to the related record to obtain fully content-designated data.  Moreover, when present, the coded data in control subfield $7 allows some types of indexing without reference to the actual related record.  The value used in the first indicator position of a linking entry field determines whether a note is to be generated from the linking entry field or from field 580.

In fields 76X-78X the general resource to resource relationship is indicated by the choice of tag with some more specific relationships indicated by indicators in fields 772, 780, and 785.  Subfield $i is used to indicate relationships not expressed in the tag or indicator, thus is appropriate for more specific relationship designations.  If it is desirable to make the specific relationship information available in a coded form or in a URI, subfield $4 is used.

Linking Entry Complexity Note (field 580) -- The Linking Entry Fields are designed to support generation of a note concerning the related item in a display of the record for the target item.  When the relationship is too complex to be expressed using relationship information expressed by the tag indicator, or $i or $4 subfields, and the data from the linking entry field or the linked record, the note is recorded in the Linking Entry Complexity Note field.  When used, this field appears in addition to any relevant 760-787 linking entry field, and no note is generated from the linking entry field.

Added Entries (fields 700-730) -- When an added entry is desired for a title used in a linking field, the added entry is recorded in the appropriate 700-730 field.  Linking fields are not intended to take the place of added entries.  Likewise, an added entry in field 700-730 does not take the place of a linking field, as it cannot cause a note to be generated or carry a record link.

Component parts/Constituent units -- The linking entry field 773 (Host Item Entry) is used to link the record for a component part that is an integral part of another item to the record for the other item.  For example, in records for journal articles, field 773 contains an identification of the journal.  The exact location of the article in the journal is recorded in subfield $g of field 773.  The record for the host item or any larger bibliographic unit may include information about constituent units recorded in the repeatable field 774 (Constituent Unit Entry).  Information about each constituent would be recorded in a separate occurrence of field 774.

See also:

76X-79X  Linking Entry Fields - General Information

76X-79X  Linking Entry Fields

Variable Data Fields