Keywords (R)
Subject(s), keyword(s), classification code(s), or key phrase(s) describing the resource (occurrences: 0-n). Try to use keyword thesauri from community-specific vocabularies.
Allowed values, examples, other constraints
List of strings.
Example
1<keywords>
2 <keyword>Chemistry</keyword>
3 <keyword>Catalysis</keyword>
4 <keyword>Confinement</keyword>
5 <keyword>Metathesis</keyword>
6</keywords>