Copyright ODRL Initiative 2004.
This Working Draft describes the semantics of the Creative Commons licenses and how they can be represented using a Profile of the ODRL rights expression language.
This is a public Working Draft of the ODRL Creative Commons Profile document. It has been produced by the ODRL Creative Commons Profile Working Group. Comments on this document should be sent to editors and discussion of this document takes place on the working group mailing list.
Publication as a Working Draft does not imply endorsement by the ODRL Initiative. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
The Creative Commons [CC] project has created a number of licenses and semantics for describing usage rights over content. The CC licenses are primarily intended to convey the semantics to the end user of the content. The ODRL is an advanced rights expression language (REL) [ODRL]. The objective of this document is to outline a Profile of the ODRL REL that incorporates the semantics and licenses from CC. This will then enable those who require more advanced REL mechanisms to utilise both the CC license semantics and the ODRL REL features.
The requirements of this Profile are to:
The CC Licenses are described by their characteristics, which come in three types:
These CC license characteristics are defined by a series of URIs, which are (respectively):
http://web.resource.org/cc/Reproduction http://web.resource.org/cc/Distribution http://web.resource.org/cc/DerivativeWorks http://web.resource.org/cc/CommercialUse http://web.resource.org/cc/Notice http://web.resource.org/cc/Attribution http://web.resource.org/cc/ShareAlike http://web.resource.org/cc/SourceCode
There are six formal licenses defined by CC (in version 2.0). These six include various combinations of the above eight terms and conditions. These are, including their unique URIs:
http://creativecommons.org/licenses/by/2.0/
http://creativecommons.org/licenses/by-nd/2.0/
http://creativecommons.org/licenses/by-nc-nd/2.0/
http://creativecommons.org/licenses/by-nc/2.0/
http://creativecommons.org/licenses/by-nc-sa/2.0/
http://creativecommons.org/licenses/by-sa/2.0/
CC defines other license types (such as Sampling etc) but does not define any new machine semantics other then those listed above.
The purpose of this Profile is not to replace the standard CC licenses, but to allow additional semantics to be expressed in separate ODRL offers or agreements.
The CC Permissions and Requirements map directly to ODRL Permissions and Requirements. ODRL already covers the semantics of CC Attribution and the others are defined in the Profile Data Dictionary (See Appendix A) and extension XML schema (See Appendix B).
CC defines two Permissions that all licenses include:
The Distribution [CC-Full] includes the right:
Both Reproduction and Distribution are examples of new semantics that are captured in the ODRL/CC Profile (see Appendix A and B).
Given now that there is an overlap in semantics of the new CC terms and the existing ODRL terms, new ODRL expressions will need to ensure that the final semantics are clear and unambiguous. For example, since the CC Reproduction right is a superset of the ODRL Print right, any expression including CC Reproduction and ODRL Print will be expressing the same rights. However, there maybe an issue if the Print included a Constraint, as then the two Permissions are in conflict. There is no general technical solution to this as the semantics involved are overlapping so care must be undertaken when creating such expressions.
However, in the cases were the rights holder does wish to be more specific with the CC Reproduction right, then the expression should not include the CC Reproduction right but only the more specific ODRL Permissions and Constraints. For example, the rights holder may only wish that their work be displayed (publicly and privately) and printed once (privately). In this case the expression would include the ODRL display and print with a Constraint, and the CC Distribution.
The current ODRL 1.1 model does not support the concept of CC Prohibitions. This is because the ODRL model indicates that if a right (permission) does not explicitly appear in the expression then it is not allowed. Hence, in an ODRL expression, if Commercial Use was prohibited, then it would simply not be mentioned in the XML code. Conversely, if Commercial Use was explicitly allowed (such as the ODRL Sell permission), then it would appear in the XML code.
There are two ways in which the CC Commercial Use semantics can be represented in ODRL. The first way would be to define Commercial Use in the negative and to make this an ODRL Constraint. The second way would be to utilise the existing ODRL Purpose constraint and define a URI for non-Commercial use. For the purposes of this Profile, it would be more flexible to define a new NonCommercialUse Constraint.
It would also be useful to add links from the ODRL expression to one of the standard CC Licenses. This will allow access to the human-readable versions of the CC semantics, as well as link the two machine expressions. The context of the entire ODRL expression can be used to indicate this reference link. Note, however, that referencing the CC License URI is an informative link - the ODRL expression is normative.
Consider the scenario described on the CC website about Anita and her song Volcano Love. Anita chooses the Attribution-NonCommercial-ShareAlike CC license. We can now express that using the ODRL CC Profile, and include additional information about Anita (as the rights holder), and direct links to the content (asset).