SubjectScheme and other "undeclared" members of the TERMS namespace

2007-03-13

For many years, the existence of classes has been asserted in 
DCMI term declarations such as [1].  These classes are:

    http://purl.org/dc/terms/DateScheme
    http://purl.org/dc/terms/FormatScheme
    http://purl.org/dc/terms/IdentifierScheme
    http://purl.org/dc/terms/LanguageScheme
    http://purl.org/dc/terms/SpatialScheme
    http://purl.org/dc/terms/SubjectScheme
    http://purl.org/dc/terms/TypeScheme

In effect, these are types of encoding scheme and serve to
associate an encoding schemes with a particular property.
For example, LCSH is a SubjectScheme - defined as "a set of
subject encoding schemes and/or formats":

    <rdfs:Class rdf:about="http://purl.org/dc/terms/SubjectScheme">
        <rdfs:label xml:lang="en-US">Subject Encoding Schemes</rdfs:label>
        <rdfs:comment xml:lang="en-US">A set of subject encoding schemes and/or formats</rdfs:comment>
        <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/"/>
        <dcterms:references rdf:resource="http://purl.org/dc/elements/1.1/subject"/>
        <dcterms:issued>2000-07-11</dcterms:issued>
      </rdfs:Class>

    <dcterms:SubjectScheme rdf:about="http://purl.org/dc/terms/LCSH">
    <rdfs:label xml:lang="en-US">LCSH</rdfs:label>
    <rdfs:comment xml:lang="en-US">Library of Congress Subject Headings</rdfs:comment>
    <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
    <rdfs:isDefinedBy rdf:resource="http://purl.org/dc/terms/"/>
    <dcterms:issued>2000-07-11</dcterms:issued>
    <dcterms:modified>2002-06-15</dcterms:modified>
    <dc:type rdf:resource="http://dublincore.org/usage/documents/principles/#encoding-scheme"/>
    <dcterms:hasVersion rdf:resource="http://dublincore.org/usage/terms/history/#LCSH-002"/>
    </dcterms:SubjectScheme>

[1] http://dublincore.org/2006/12/18/dcq.rdf