License expression link (content item)

The URI for the license expression. Mandatory in each instance of the <EpubLicenseExpression> composite, and non-repeating.

Format	Variable length text, suggested maximum length 300 characters
ReferenceName	<EpubLicenseExpressionLink>
ShortTag	<x510>
Cardinality	1
Example	http://creativecommons.org/licenses/by/3.0/deed.en_GB