license-type Type of License

Type of license described by the <license> element.
OPTIONAL on element: <license>
Value Meaning
Text, numbers, or special characters The type of license, for example, “open-access” for a license permitting unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited; or “ccc” for a Copyright Clearance Center statement.
Restriction This is an optional attribute; there is no default.