Page "Dublin Core" Paragraph 31

In addition to element refinements, Qualified Dublin Core includes a set of recommended encoding schemes, designed to aid in the interpretation of an element value.

These schemes include controlled vocabularies and formal notations or parsing rules.

A value expressed using an encoding scheme may thus be a token selected from a controlled vocabulary ( for example, a term from a classification system or set of subject headings ) or a string formatted in accordance with a formal notation, for example, " 2000-12-31 " as the ISO standard expression of a date.

If an encoding scheme is not understood by an application, the value may still be useful to human reader.