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<nested-kwd> Nested Keyword

Hierarchical or nested keyword, in which several levels of a taxonomy that pertains to the standard can be described.

Usage/Remarks

Language in Keywords
Keywords are contained in <kwd-group> elements. There may be several <kwd-group>s, each of which can be identified separately by language, vocabulary, or taxonomy source. Since different languages could mean, for example, different writing directions, none of the individual keyword elements (<kwd>, <compound-kwd>, <nested-kwd>) take the @xml:lang attribute; that is reserved for the <kwd-group> element. This means that if there are keywords in several languages they should be in different <kwd-group>s.
Vocabulary Attributes
For controlled vocabularies, two attributes can be used to link a keyword to its term source:
  • @vocab-term — This attribute holds the canonical form of the keyword as expressed in the vocabulary named in the <kwd-group>. The content of the keyword element (<kwd>, <compound-kwd>, <nested-kwd>) might not be exactly the same as the canonical form, as the keyword element content might be a user-specific variant, for example, the term in another language.
  • @vocab-term-identifier — This attribute holds a unique identifier and possible pointer to the specific term in the named vocabulary (typically a URI or DOI reference), but @vocab-term-identifier could be an item number or other system-specific identifier.
Related Elements
Types of Keywords: This Tag Set contains several differently-structured types of keywords:
  • <kwd> Used with simple keywords, such as words or phrases.
  • <compound-kwd> Used with multi-part keywords, such as keywords that contain both a code and its expansion/description/name/title.
  • <nested-kwd> Used with hierarchical keyword structures, such as taxonomies, to record a portion of a taxonomic hierarchy. Both simple and compound keywords can be nested hierarchically.
Keywords vs Subjects Terms: Subject terms (collected within a <subj-group> element) name broad classifications, categories, topics, or themes that describe or classify a standard. Keywords (collected within a <kwd-group> element) contain words from the narrative text or words (such as broader and narrower terms) related to that text.
Attributes
content-type
specific-use
vocab-term
vocab-term-identifier

Base Attributes

id
xml:base
Models and Context
May be contained in
<kwd-group>, <nested-kwd>
Description
The following, in order:
Content Model
<!ELEMENT  nested-kwd   %nested-kwd-model;                           >
Expanded Content Model

((kwd | compound-kwd)+, nested-kwd*)

Tagged Sample

3-level nested list

...
<kwd-group kwd-group-type="xyw-food-taxonomy">
 <nested-kwd>
  <kwd>beverages</kwd>
  <nested-kwd>
   <kwd>alcoholic</kwd>
   <nested-kwd>
    <kwd>beer</kwd>
    <kwd>martini</kwd>
    <kwd>wine</kwd>
   </nested-kwd>
  </nested-kwd>
  <nested-kwd>
   <kwd>dairy</kwd>
   <nested-kwd>
    <kwd>milk</kwd>
    <kwd>drinkable yogurt</kwd>
    <kwd>milkshakes</kwd>
   </nested-kwd>
  </nested-kwd>
 </nested-kwd>
</kwd-group>
...
Related Resources