CC REL by Example - Creative Commons

"You may have noticed that the copy-and-paste HTML you get from the CC license chooser includes some strange attributes you’re probably not familiar with. That is RDFa metadata, and it allows for the CC license deeds, search engines, Open Attribute, and other tools to discover metadata about your work and generate attribution HTML. Many platforms have implemented CC REL metadata in their CC license marks, such as Connexions and Flickr, and it’s our recommended way to mark works with a CC license. In an effort to make CC license metadata (or CC REL metadata) much easier to implement, we’ve created CC REL by Example....Even if you just use CC licenses for your own content, now is a great time to take a first step into structured data and include information about how you’d like to be attributed...."