Library of Congress >> MARC >> Community Information >> Appendix A

Appendix A - Control Subfields

MARC 21 Community Information
October 2007

Subfield Codes
$0 - Authority record control number
$6 - Linkage
$8 - Field Link and Sequence Number

Descriptions of three subfields that are used to link field data to other fields. These subfields are defined for most fields in the format, and thus their descriptions are brought together in this appendix. The subfields are included in field level subfield lists wherever defined, with pointers to this appendix.


$0 - Authority record control number
System control number of the related authority record preceded by the MARC code, enclosed in parentheses, for the agency to which the control number applies. See Organization Code Sources for a listing of sources used in MARC 21 records.
100 1#$aBach, Johann Sebastian.$4aut$0(DE-101c)310008891
$6 - Linkage
Data that links fields that are different script representations of each other. Subfield $6 may contain the tag number of an associated field, an occurrence number, a code that identifies the first script encountered in a left-to-right scan of the field, and an indication that the orientation for a display of the field data is right-to-left. A regular (non-880) field may be linked to one or more 880 fields that all contain different script representations of the same data. Subfield $6 is structured as follows:
$6[linking tag]-[occurrence number]/[script identification code]/[field orientation code]
Subfield $6 is always the first subfield in the field.
Descriptions of multiscript records, with examples, are in Appendix C of the MARC 21 Format for Community Information; specifications for field 880 are under that field; specifications for character sets and repertoires for scripts are found in MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media.
Linking tag part contains the tag number of the associated field. This part is followed immediately by a hyphen and the two-digit occurrence number part. A different occurrence number is assigned to each set of associated fields within a single record. The function of an occurrence number is to permit the matching of the associated fields (not to sequence the fields within the record). An occurrence number may be assigned at random for each set of associated fields. An occurrence number of less than two digits is right justified and the unused position contains a zero.
066 ##$c)S
110 2#$6880-15$a[Primary Name]
270 ##$6880-05$a[Primary Address]
301 ##$a[Hours, Etc.]
500 ##$a[General Note
531 ##$6880-01$a[Eligibility, Fees, Procedures Note]
700 1#$6880-22$a[Added Entry-Personal Name]
880 2#$6110-15/)S$a[Primary Name]
880 ##$6270-05/)S$a[Primary Address]
880 ##$6531-01/)S$a[Eligibility, Fees, Procedures Note]
880 1#$6700-22/)S$a[Added Entry-Personal Name]
[")S" = 29hex 53hex = Identification of the first alternate character set that will be encountered in the field.]
When there is no associated field to which a field 880 is linked, the occurrence number in subfield $6 is 00. It is used if an agency wants to separate scripts in a record. The linking tag part of subfield $6 will contain the tag that the associated regular field would have had if it had existed in the record.
110 2#$6880-01$aHeading in Latin script
880 2#$6110-01/(2/r$a[Heading in Hebrew script linked to associated field]
880 ##$6531-00/(2/r$a[Eligibility, fees, procedures information in Hebrew script]
[The second 880 field is not linked to an associated field. The occurrence number is 00.]
Occurrence number is followed immediately by a slash (/) and the script identification code. This code identifies the alternate script found in the field. The following codes are used:
Code Script
(3 Arabic
(B Latin
$1 Chinese, Japanese, Korean
(N Cyrillic
(S Greek
(2 Hebrew
880 1#$6100-01/(N$a[Heading in Cyrillic script]
Entire field need not be in the script identified in subfield $6. If more than one script is present in the field, subfield $6 will contain the identification of the first alternate script encountered in a left-to-right scan of the field.
Note also that the script identification code is used in field 880, subfield $6, but this data element is not generally used for subfield $6 of the associated regular field. In the associated field, the data is assumed to be the primary script(s) for the record.
In a MARC record, the contents of field 880 are always recorded in their logical order, from the first character to the last, regardless of field orientation. For a display of the field, the default field orientation is left-to-right. When the field contains text that has a right-to-left orientation, the script identification code is followed by a slash (/) and the field orientation code. The MARC field orientation code for right-to-left scripts is the letter r. The orientation code is only included in fields with right-to-left orientation, since left-to-right orientation is the default orientation in 880 fields. (See MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media for a detailed description of field orientation.)
Note that the orientation code is used in field 880, subfield $6, but this data element is not generally used for subfield $6 of the associated regular field. In the associated field, the data is assumed to be the usual orientation of the primary script(s) for the record.
$8 - Field Link and Sequence Number
Data that identifies linked fields and may also propose a sequence for the linked fields. Subfield $8 may be repeated to link a field to more than one other group of fields. The structure and syntax for the field link and sequence number subfield is:
$8[linking number].[sequence number]\[field link type]
Linking number is the first data element in the subfield and required if the subfield is used. It is a variable-length whole number that occurs in subfield $8 in all fields that are to be linked. Fields with the same linking number are considered linked.
Sequence number is separated from linking number by a period "." and is optional. It is a variable- length whole number that may be used to indicate the relative order for display of the linked fields (lower sequence numbers displaying before higher ones). If it is used it must occur in all $8 subfields containing the same linking number.
Field link type is separated from preceding data by a reverse slash "\". It is a code indicating the reason for the link and it follows the link number, or sequence number if present. No field link types have been defined in the MARC 21 Format for Community Information.


$0 - Authority record control number [NEW, 2007]

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