3.6.2 Classification domain elements
The classification domain elements are used to identify
the subject matter of content that is referenced in a map. These subjects
must be subjects defined in a subject scheme map. In particular, this
allows an author to classify content in new subject categories that
are not bound to existing metadata attributes.
<subjectref> element identifies a subject to classify content. The
<subjectref> can identify the subject with a
@keyref attribute (if the scheme has a
<subjectdef> with a
@keys attribute that assigns a key to the subject) or an
@href attribute (if the scheme is not available and a topic exists that defines the subject).
<topicapply> element identifies subjects that qualify the content for filtering or flagging but not retrieval. The
<topicapply> element can identify a single subject. Additional subjects can be specified by nested
<topicsubject> element identifies the subjects covered by a topic or map.
<topicSubjectTable> element is a specialized relationship table which allows a map to use relationship tables to associate topics with subjects. Tools (such as search tools)
might use these classifications to retrieve content that is relative to a specific subject or combination of subjects.
<topicSubjectHeader> element specifies constraints on the subjects used in classifications.
<topicSubjectRow> is a grouping element that contains one row of a subject table. It contains topic references in the first column, and relates those references to the subjects in each following column.
<topicCell> element contains topics that will be associated with subjects in each following column of the current row in the
<subjectCell> element contains subjects that are associated with topics in the first column of the current row in the
<topicSubjectTable>. The subjects themselves have no defined relationship across columns, other than the fact that they apply to the same content.