Clarity for lexicographers. Stability for data. Compatibility for the future.
10.1.66. <langKnowledge>
<langKnowledge> (language knowledge) summarizes the state of a person's linguistic knowledge, either as prose or by a list of <langKnown> elements. [14.3.2.1. Personal Characteristics]
This attribute should be supplied only if the element contains no <langKnown> children. Its values are language ‘tags’ as defined in RFC 4646 or its successor