Related Work

This page provides a summary and background on some relevant related vocabularies for licensing metadata.

The emphasis here is on vocabularies and schemas that support the description of Open Data or open content. There are many generic rights expression languages.

Dublin Core

Dublin Core includes several terms that relate to the description or referencing of licensing terms:

• dct:license -- reference to a legal document giving official permission to do something with the resource.
• dct:rights -- reference to a statement that typically described property rights associated with the resource, including intellectual property rights.
• dct:rightsHolder -- a person or organisation owning or managing rights over the resource
• dct:LicenseDocument -- a legal document giving permission to do something with a resource
• dct:RightsStatement -- a statement about the intellectual property rights (IPR) held in or over a Resource, a legal document giving official permission to do something with a resource, or a statement about access rights.

The dct:LicenseDocument and dct:RightsStatement classes are not further specified, and based on a brief investigation, no further work has been carried out to refine their meanings.

The dct:license property is in active usage and is recommended by both the VoiD and DCAT vocabularies. VoiD recommends use of the term to relate a Dataset to a license, e.g. an Open Database License. DCAT uses the term to relate either a Catalog or a Distribution (but not a Dataset) to a license document, which may have a machine-readable description.

Creative Commons Rights Expression Language

The Creative Commons Rights Expression Language (ccRel) provides terms for describing a vocabulary in RDF. For more background see the W3C Member Submission and the ccRel By Example guide.

The vocabulary defines:

• a set of Requirements (e.g. attribution), Permissions (e.g. ability to create derivative works) and Prohibitions (e.g. commercial usage) that describe the key aspects of a License. These are essentially ways to classify a cc:License.
• basic license life-cycle metadata is handled by a cc:deprecatedOn property which supplements the Dublin Core dct:isReplacedBy and dct:hasVersion properties
• a License can be related to other resources, e.g. its legal definition (cc:legalCode), usage guidelines (cc:useGuidelines) and documentation on additional permissions or alternative licensing options (cc:morePermissions)
• cc:attributionName is used to identify the name of the author or creator of the work for attribution purposes
• cc:attributionURL is used to provide the preferred URL for attributing usage of a work. This might be the URL of the work itself or a pointer to the homepage of the creator. Expected usage seems to be a preference for the former (i.e. a link to the original work)
• The cc:license property is used to relate a Work to its License.

RDF versions of each of the CC licenses are available. These provide examples of expected usage for describing vocabularies. The the ccRel By Example guide provides examples of using the vocabulary for attributing works, e.g. a photo in a webpage.

The vocabulary is well deployed for attributing works as is the simple rel-license microformat which seems to share a common origin.

Its worth noting that the Creative Commons marking guidelines for users explains that copyright notices associated with CC licensed works should be preserved by re-users. However the vocabulary provides no way to define these notices in a machine-readable way. The closest available option is the older, Dublin Core Elements term: dc:rights which can be used to reference to a literal value, e.g. "Copyright 2010, Acme Ltd."

WAIVER

The WAIVER vocabulary provides terms for describing waivers of rights over content. These terms cover:

• A wv:declaration a statement of the waiving of rights, expressed as a literal
• A wv:norms relation to a document describing a set of norms
• A wv:waiverrelation referencing a legal document that describes the waiver

The vocabulary is a companion to the ccRel vocabulary, but with a specific focus on the public domain.