<http://schema.org/category>
"print ready license"^^<http://www.w3.org/2001/XMLSchema#string>
<https://marketplace.500px.com/photos/18722589/r%25C3%25ADa-del-as%25C3%25B3n-by-jos%25C3%25A9-luis-pell%25C3%25B3n>