<compound-subject> Compound Subject Name
Wrapper element to hold all the parts of a multi-part subject (for example, a subject term and the code representing that term).
When to Use
A <compound-subject-part> may be used if a subject has multiple parts, but need not be used unless both parts need to be captured:
- If a subject is only a word or phrase (Neuroscience, Physical Sciences), the simple <subject> element can be used to capture this information (“<subject>Neuroscience</subject>” or “<subject>Physical Sciences</subject>”).
- If a subject contains both a term and a code (A11 Permeability) but only one of those objects needs to be captured, a <subject> element may still be used, to record either the code (“<subject>A11</subject>”) or the subject (“<subject>Permeability</subject>”). If such a compound subject is considered to be a single subject, the <subject> element may also be used: “<subject>A11 Permeability</subject>”.
- If a subject contains both a term and a code, and it is useful to record both the code and the term separately, each can be captured as a <compound-subject-part> inside a <compound-subject>. (See tagged examples below.)
Language in Subjects
A standard may take multiple sets of subject codes, with the @subj-group-type, @specific-use, or @xml:lang attributes used to discriminate between them. The <compound-subject> element does not take the @xml:lang attribute; that is reserved for the <subj-group>. This means that subjects must be sorted by language and entered in language groups.
For controlled vocabularies, two attributes on <subj-group> name the source vocabulary: @vocab and @vocab-identifier. On the <compound-subject> element, two lower-attributes provide more information about the specific subject term:
- @vocab-term — This attribute holds the canonical form of the term. (Note: The content of the element to which this attribute is attached is the free prose version of the vocabulary or taxonomic term.)
- @vocab-identifier — This attribute holds a unique identifier and possibly a pointer to the named vocabulary term, for vocabularies that provide term-level access.
Vocabulary Attributes Best Practice
If the subject terms in <subj-group> come from a controlled vocabulary, taxonomy, ontology, database, term list, or similar formally defined term source, the @vocab attribute (and if possible, the @vocab-identifier attribute) should be used on the <subj-group> element to name the source. If there is a subject-term-specific identifier in this source of terms, then also use the @vocab-term and @vocab-term-identifier on the subject term (<subject>), if possible.
If the subject terms come from, or are specific to, a field of study that can be named (particularly where different fields might define the same term differently), name the field of study in the @subj-group-type attribute (“structural engineering”, “mechanical engineering”, “bird watching”). Such terms are typically, but not always, informally defined.
Although subject terms may be from an uncontrolled vocabulary, this is less likely than for terms such as keywords, since subject codes such as IPC, UNSPSC, UNS, etc. are controlled by defined vocabularies. If the subject terms are uncontrolled, either omit the @vocab attribute on <subj-group> or use the value “uncontrolled”.
Models and Context
May be contained in
<!ELEMENT compound-subject %compound-subject-model; >
Expanded Content Model
IPC subject codes/descriptions
... <subj-group vocab="ipc"> <compound-subject> <compound-subject-part content-type="code">B82B1/00</compound-subject-part> <compound-subject-part content-type="value">Nano structures</compound-subject-part> </compound-subject> <compound-subject> <compound-subject-part content-type="code">H01L21/02</compound-subject-part> <compound-subject-part content-type="value">Manufacture or treatment of semiconductor devices or of parts thereof</compound-subject-part> </compound-subject> </subj-group> ...
UNSPSC codes with their descriptions given using <compound-subject>
... <subj-group vocab="UNSPSC"> <compound-subject> <compound-subject-part content-type="code">30102204</compound-subject-part> <compound-subject-part content-type="value">Steel Plate</compound-subject-part> </compound-subject> </subj-group> ...