Page:The digital public domain.pdf/189

162 terms exhibit? Given the use cases we have observed over the past several years, we can call out the following four desiderata.

Independence and Extensibility: We cannot know in advance what new kinds of data we will want to integrate with CC licensing data. Currently, we already need to combine CC properties with simple media files (sound, images, videos) and there is a growing interest in providing markup for complex scientific data (biomedical records, experimental results). Therefore, the means of expressing the licensing information in HTML should be extensible: it should enable the reuse of existing data models and the addition of new properties, both by CC and by others. Adding new properties should not require extensive coordination across communities or approval from a central authority. Tools should not suddenly become obsolete when new properties are added, nor when existing properties are applied to new kinds of data sets.

DRY (Don’t Repeat Yourself): An HTML document often already displays the name of the author and a clickable link to a CC license. Providing machine-readable structure should not require duplicating this data in a separate format. Notably, if the human-clickable link to the license is changed, for example, from v2.5 to v3.0, a machine processing the page should automatically note this change without the publisher having to update another part of the HTML file to keep it “in sync” with the human-readable portion.

Visual Locality: An HTML page may contain multiple items, for example a dozen photographs, each with its own structured data and a different license. It should be easy for tools to associate the appropriate structured data with their corresponding visual display. Remix Friendliness: It should be easy to copy an item from one document and paste it into a new document with all appropriate structured data included. In a world where we constantly remix old content to create new content, copy-and-paste, widgets, and sidebars are crucial elements of the remixable Web. As much as possible, CC REL should allow for easy copy-and-paste of data to carry along the appropriate licensing information.

3.2 Desiderata for Free-Floating Content

Some important works are not typically conveyed via HTML. Examples are MP3s, MPEGs, and other media files. The technique for embedding licensing data into these files should achieve the following design principles.