Common Tag semantic tagging format released today

The Common Tag format for semantic tagging has been finally released today after almost a year of intense work on it by a group of Web companies active in the semantic technologies area, among them Yahoo. It’s been great fun working on this and I’m proud to have been involved: while there have been vocabularies before for representing tags in RDF, this effort is different in at least two respects.

First, a significant effort of time has been spent on making sure the specification meets the needs of all partners involved. The support of these companies for the specification will ensure that developers in the future can rely on a single format for annotation with semantic tags and interchanging tag data. The website already lists a number of applications but I’m pretty sure that a common tagging format will open entirely new possibilities in searching, navigating and aggregating web content.

Second, the format has been developed with publishers in mind, in particular in making it as easy as possible to embed semantic tags in HTML using RDFa, a syntax universally embraced by all those involved. The choice for RDF also means that unlike in the case of the rel-tag microformat, Common Tags can be applied to any object, not just documents.

So, it’s time for a new era in tagging!

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7 comments so far

  1. Bruce on

    This is an interesting effort, but why couple the effort so closely to a particular RDF serialization (RDFa), when in theory it would be equally usable with others? I suggest you tweak the language of the spec and documentation to make clear that RDFa is just one way to encode the data.

    • tripletalk on

      Hi Bruce,

      It is absolutely true that Common Tag –being a vocabulary– can be used with any RDF serialization. However, it is also my experience that many vocabularies that have not been designed with semantic annotation in mind do not lend naturally to annotating HTML pages. As we expect RDFa-in-HTML to be a major source of tagging information, we made sure that Common Tag is easy to embed in HTML.


  2. Bruce on

    I’m not saying that’s a wrong approach. What I think is a problem is the fact that the language of the docs suggests (at least to me) this is only for HTML and RDFa. Is that what you really want to communicate?

    Just as an example, I could imagine the Zotero project might well want to use something like this to enhance their tagging support. But the content their users are referring to are not always web pages, and that data will not only or always be published/visible as HTML.

    • tripletalk on

      I actually don’t expect this to be a problem: those familiar with RDF and RDFa will immediately recognize the possibility for other use cases and in fact nothing is in the way to implement what you just described. As I mentioned, we are focusing on what we expect to be the majority use case but we are happy to report on other use cases. As you’ve seen on the site, we are collecting applications of the technology so please tell us if you know of any new ones.

      • Bruce on

        OK, let me be specific, and see if you still agree with me about the language.

        The very first sentence of the quick start guide is Common Tags are defined using RDFa, a standard format for expressing structured data within HTML.

        Well, no; that’s simply not true. The tags “may” be so “encoded” in RDFa, but they are actually defined in a higher level modeling language (RDF).

        I don’t have a problem understanding the distinction because I’m very comfortable with RDF and RDFa. But I do know a lot of potential developers who are intrigued by or at least open to exploring the technology, but not at all fluent in it. I can guarantee you they will be confused.

        So my suggestion to start: change that sentence to Common Tags may be encoded using RDFa, a standard format for expressing structured data within HTML.

  3. […] the semantic technologies area, among them Yahoo. It’s been great fun working on this and… [full post] tripletalk Tripletalk uncategorized 0 0 0 0 0 […]

  4. enzus on


    FYI the website seems to be down.

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