Matt Croydon writes: "I know that the Creative Commons licenses have all kinds of other implications, I just can't think of them right now." Here's one that seems pertinent as Creative Commons launches and people begin applying its licenses to their work: what suffices to establish a Creative Commons license that both parties (creator and user) can be reasonably comfortable will govern their activities?* Dave Winer gives the example of his picture of Shawn Fanning, and also now has deployed an RSS Module intended to convey information about applicable CC licensing in the XML version of a Web page. This begs the question: is it enough to have information about the license in the HTML, RSS/XML or metadata? (I.e., otherwise "invisible" when one is reading a Web page or other otherwise directly accessing a digital work?) Nope, I don't think so, and I don't think CC thinks so either. On the site, users are told that Web pages should incorporate specific HTML and RDF to "tag" the work as subject to a particular license. That code is designed to link the user back to the relevant CC Commons Deed and the actual license (the legalese) that the Commons Deed represents (click on the line "Legal Code (the full license)" in any Commons Deed to access). Apropos of Dave's Shawn Fanning photo example, users also are told that once a license has been chosen, "You should then include a Creative Commons 'Some Rights Reserved' button on your site, near your work. Help and tips on doing this are covered here. This button will link back to the Commons Deed, so that the world can be notified of the license terms. If you find that your license is being violated, you may have grounds to sue under copyright infringement." (Emphasis added.) This is all pretty apparently intended to strengthen the enforceability of the CC licenses. As stated in CC's FAQ, "We and our lawyers have worked hard to craft the licenses to be enforceable in as many jurisdictions as possible. That said, we can not account for every last nuance in the world's various copyright laws, at least not given our current resources." License information that is visibly and textually displayed on the site helps eliminate confusion and disagreement more effectively than something that lives exclusively in HTML or metadata. This point is bolstered by CC's explanation about why it offers a metadata component at all:

If you run a search engine, you might use license metadata to highlight public domain and generously-licensed works. If you write a public file sharing server, you might offer to search the user's hard drive for works that allow distribution. If you write a magazine, you might use a CC-enabled search engine to find pictures of candy bars that you can legally include. ... Of course, this metadata only provides a first approximation of the license, for information use. Users are encouraged to read the full license to make sure it meets their expectations. [Why We Have Creative Commons Metadata]

In other words, the metadata is informational. It helps with the location and dissemination of licensed works. It's several layers removed from the actual license. At some point, courts may be inclined to enforce a license that exists purely in machine readable form, or that is largely or completely invisible to a casual observer. We're probably a long way off from that day however, and it seems to me Creative Commons takes this into account by implementing a plan designed to include obvious visual and text cues in proximity to licensed works. *Here's another that Matt's page highlights: notwithstanding the intent of Creative Commons (at least for the time being) not to have its licenses apply to software (see Larry Lessig and the CC FAQ), this is happening anyway. I don't see a "no software" disclaimer in the licenses themselves -- a "work" is defined as "copyrightable work of authorship" -- and thus don't see why these could not form an enforceable software license (??). It would have to be free software, as the CC licenses aren't designed to help collect fees or royalties from use. [Update]: Woah. Seems folks much closer to this issue than I on the technical side also are intrigued.