FieldOfNumismatics
IRI: http://nomisma.org/ontology#FieldOfNumismatics
Class instances: nm:roman_numismatics, nm:greek_numismatics, nm:united_states_numismatics, …
Note: Any widely recognized area of study within the discipline of numismatics.
Use case:

RDF/XML:<rdf:Description rdf:about="collection_1">
<dcterms:isPartOf rdf:resource="nm:roman_numismatic"/>
</rdf:Description>