This ended up being a marathon thread about OpenURL, accessibility, bibliographic metadata, and more. It spilled over onto a previous blog post (Tight versus loose coupling) where Ed Summers and I debated the merits of Context Object in Span (COinS).
This debate still nags at me because I think there's an underlying assumption that people making bibliographic web sites know what's best for their users.
I prefer to encourage publishers to use HTML's metadata facilities using the <meta> tag and microdata/RDFa, and build actually useful tools that do something useful with it, like Zotero or Mendeley have done.
That's fine, I like embedded metadata, both as a consumer and as a provider (I provide Google Scholar-compatible metadata in BioStor). What I object to is the idea that this is all we need to do. Embedded metadata is great if you want to make individual articles visible to search engines:
Tools like Google (or bibliographic managers like Mendeley and Zotero) can "read" the web page, extract structured data, and do something with that. Nice for search engines, nice for repositories (metadata becomes part of their search engine optimisation strategy).
But this isn't the only thing a user might want to do. I often find myself confronted with a list of articles on a web site (e.g., a bibliography on a topic, a list of references cited in a paper, the results of a bibliographic search) and those references have no links. Often those links may not have existed when original web page was published, but may exist now. I'd like a tool that helped me find those links.
If a web site doesn't provide the functionality you need then, luckily, you are not entirely at the mercy of the people who made the decisions about what you can and can't do. Tools like Greasemonkey pioneered the idea that we can hack a web page to make it more useful. I see COinS as an example of this approach. If the web page doesn't provide links, but has embedded COinS then I can use those to create OpenURL links to try and locate those references. I am no longer bound by the limitations of the web page itself.
This strikes me as very powerful, and I use COinS a lot where they are available. For example, CrossRef's excellent search engine supports COinS, which means I can find a reference using that tool, then use the embedded COinS to see whether there is a version of that article digitised by the Biodiversity Heritage Library. This enables me to do stuff that CrossRef itself hasn't anticipated, and that makes their search engine much more valuable to me. In a way this is ironic because CrossRef is predicated on the idea that there is one definitive link to a reference, the DOI.
So, what I found frustrating about the conversation with Ed was that it seemed to me that his insistence on following certain standards was at the expense of functionality that I found useful. If the client is the search engine, or the repository, then COinS do indeed seem to offer little apart from God-awful HTML messing up the page. But if you include the user and accept that users may want to do stuff that you don't (indeed can't) anticipate then COinS are useful. This is the "genius of and", why not support both approaches?
Now, COinS are not the only way to implement what I want to do, we could imagine other ways to do this. But to support the functionality that they offer we need a way to encode metadata in a web page, a way to extract that metadata and form a query URL, and a set of services that know what to do with that URL. OpenURL and COinS provide all of this right now and work. I'd be all for alternative tools that did this more simply than the Byzantine syntax of OpenURL, but in the absence of such tools I stick by my original tweet:
If you publish bibliographic data and don't use COinS you are doing it wrong