We knew at the time that this was a cumbersome design, but there was little alternative. RDF/XML, despite its verbosity, was the only standard syntax for expressing RDF. Worse, the Web Consortium’s Semantic Web Activity was focused on providing organisations with ways to annotate databases for integration into the Web, and it paid scant attention to the issues of intermixing semantic information with visible Web elements. A task force had been formed to address these issues, but there was no W3C standard for including RDF in HTML pages.
One consequence of CC’s limited initial design is that, although millions of webpages now include CC licenses and metadata, there is no uniform, extensible way for tool developers to access this metadata, and the tools that do exist rely on ad-hoc techniques for extracting metadata.
Since 2004, CC has been working with the Web Consortium to create more straightforward and less limited methods of embedding RDF in HTML documents. These new methods are now making their way through the W3C standards process. Accordingly, CC no longer recommends using RDF/ XML in HTML comments for specifying licensing information. This chapter supersedes that recommendation. We hope that the new CC REL standard presented in here will result in a more consistent and stable platform for publishers and tool builders to build upon Creative Commons licenses.
- 2. The CC REL abstract model
This section describes CC REL, CC’s new recommendation for machine-readable licensing information, in its abstract form, i.e., independent of any concrete syntax. As an abstract specification, CC REL consists of a small but extensible set of RDF properties that should be provided with each licensed object. This abstract specification has evolved since the original introduction of CC properties in 2002, but it is worth noting that all first-generation licenses are still correctly interpretable against the new specification, thanks in large part to the extensibility properties of RDF itself.
The abstract model for CC REL distinguishes two classes of properties: work properties describe aspects of specific works, including under which license a work is distributed; and license properties describe aspects of licenses.
Publishers will normally be concerned only with work properties: this is the only information publishers provide to describe a work’s licensing terms. License properties are used by CC itself to define the authoritative specifications of the licenses we offer. Other organisations are free to use
