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Subject headings and classification


Subject headings - optional
Definition Subject headings are text entries that provide a description of the content of a publication and contribute to its optimal retrieval.
General notes ---

MARC 21 ONIX 3.0.8 Reference Names
 		ONIX 3.0.8 Short Tags
Format 650 $a

<Subject>
/ONIXMessage/​Product/​DescriptiveDetail/​Subject

<SubjectSchemeIdentifier> with value 20 "Keywords" from code list 27
/ONIXMessage/​Product/​DescriptiveDetail/​Subject/​SubjectSchemeIdentifier

<SubjectHeadingText>
/ONIXMessage/​Product/​DescriptiveDetail/​Subject/​SubjectHeadingText

<subject>

         <b067> with value 20 "Keywords" from code list 27

         <b070>
Format notes
 		Field 650 is intended for the specification of subject headings. 
Subject headings for other entities can be specified in other 6XX categories (e.g. subject headings for personal names in field 600). See https://www.loc.gov/marc/bibliographic/bd6xx.html and the following subpages on the individual categories.		 ---
Example 650 #4$aMedicine
650 #4$aBiomedicine
650 #4$aHuman Physiology

<Subject>
 <SubjectSchemeIdentifier>20</SubjectSchemeIdentifier>
 <SubjectHeadingText>Medicine</SubjectHeadingText>
</Subject>
<Subject>
 <SubjectSchemeIdentifier>20</SubjectSchemeIdentifier>
 <SubjectHeadingText>Biomedicine</SubjectHeadingText>
</Subject>
<Subject>
 <SubjectSchemeIdentifier>20</SubjectSchemeIdentifier>
 <SubjectHeadingText>Human     Physiology</SubjectHeadingText>
</Subject>

<subject>
 <b067>20</b067>
 <b070>Medicine</b070>
</subject>
<subject>
 <b067>20</b067>
 <b070>Biomedicine</b070>
</subject>
<subject>
 <b067>20</b067>
 <b070>Human Physiology</b070>
</subject>


Classification - optional
Definition Classifications are assigned to describe the content of the product. They are particularly useful for searching and finding products.
General notes ---

MARC 21  ONIX 3.0.8 Reference Names ONIX 3.0.8 Short Tags
Format

082 $a $2
084 $a $2

<Subject>
/ONIXMessage/​Product/​DescriptiveDetail/​Subject

<SubjectSchemeIdentifier> with code list 27
/ONIXMessage/​Product/​DescriptiveDetail/​Subject/​SubjectSchemeIdentifier

<SubjectCode>
/ONIXMessage/​Product/​DescriptiveDetail/​Subject/​SubjectCode

<subject>

         <b067> with code list  27

         <b069>


Format notes

Notations from the Dewey Decimal Classification (DDC) are given in field 082. This also includes the "DDC-Sachgruppen" of the German National Bibliography. Subfield $2 specifies the scheme according to which the DDC notation was created.

Notations from other classifications or notation systems are recorded in field 084 and the system used is specified with a code in subfield $2 (see http://www.loc.gov/standards/sourcelist/classification.html).

In ONIX 3.0.8, one subject composite is flagged with the empty tag <MainSubject/> or <x425/>. All other classifications are specified in further subject composites.
Example

082 04$a612.044$223/ger
082 74$a610$223sdnb



<Subject>
 <MainSubject/>
 <SubjectSchemeIdentifier>01</SubjectSchemeIdentifier>
 <SubjectCode>612.044</SubjectCode>
</Subject>
<Subject>
 <SubjectSchemeIdentifier>18</SubjectSchemeIdentifier>
 <SubjectCode>610</SubjectCode>
</Subject>

<subject>
 <x425/>
 <b067>01</b067>
 <b069>612.044</b069>
</subject>
<subject>
 <b067>18</b067>
 <b069>610</b069>
</subject>


2023-06-01
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