The description
head
element contains meta information about the enclosing
description
element.
The meta information in the description
head
element should not be treated as document content, but may be used for display and other purposes when rendering descriptions.
Although all metadata is optional, descriptions should, at a minimum, include an identifier, the intended reader age and/or school grade level. See the DIAGRAM Descriptions Vocabulary for a set of predefined RDF properties. Properties from other RDF vocabularies can also be included, provided their prefix is declared.
If age and grade-level metadata is omitted, the containing
description
should be assumed to be applicable to all readers.