|First Indicator||Second Indicator|
# - Undefined
0 - Library of Congress Subject Headings
1 - LC subject headings for children's literature
2 - Medical Subject Headings
3 - National Agricultural Library subject authority file
4 - Source not specified
5 - Canadian Subject Headings
6 - Répertoire de vedettes-matière
7 - Source specified in subfield $2
Explanatory text and the headings referred to when the linking relationship between headings from different subject heading systems or thesauri cannot be adequately conveyed by fields 700-785. No subelements of the heading referred to are separately subfield coded. Adjacent headings referred to may be contained in a single subfield $a. The heading referred to may be an established heading or a subject subdivision that is not equivalent to but is related to the heading in the 1XX field.
For example, the heading referred to may be restricted to being used as a subdivision in the related subject heading system/thesaurus, or, the related subject heading system/thesaurus may require the use of more than one heading to equal the concept expressed by the heading in the 1XX field of the record.
A link display may be generated from the 1XX field and field 788 in a record. The 1XX field contains the heading referred from. Field 788 contains the explanatory text for the reference and the other headings referred to. Subfield $w/0 in any related 700-785 field(s) in the record contains code b (Link not displayed, field 788 used).
First Indicator - Undefined
Undefined and contains a blank (#).
Second Indicator - Thesaurus
Description of the second indicator is given in the 7XX Heading Linking Entries—General Information section.
$a - Heading referred to
Heading from another thesaurus to which the heading in field 1XX of the record refers.
$i - Explanatory text
Text that describes the relationship between the heading referred to in subfield $a and the 1XX heading. The text may be broken up by subfield $a data and may be only a connector term such as and. See also "Relationship information" described in 7XX Heading Linking Entries—General Information.
$2 - Source of heading or term
Description of subfield $2 is given in the 7XX Heading Linking Entries—General Information section.
$4 - Relationship code
Description of subfield $4 is given in the 7XX Heading Linking Entries—General Information section.
$5 - Institution to which field applies
$6 - Linkage
$8 - Field link and sequence number
Same term used as established heading and as subject subdivision by different thesauri:
[established heading record]
[code indicating MeSH]
|780||#0$w#$xForeign bodies [LCSH subdivision]|
|788||#0$isubdivision$aForeign bodies$iunder names of organs, e.g.$aEye-Foreign bodies|
Two established heading terms in one thesaurus are equivalent to one established heading in another thesaurus:
[established heading record]
[code indicating LCSH]
|788||#7$iterms$aChinese$iand$aFurniture$iare separate facets.$2aat|