Machine tags and ISBNs

About a year ago I wrote about how tagging had become more than just a way to annotate content with keywords. Tags had become the wires by which disparate content could be connected. Through use of consistent and detailed tagging, I could begin associating my blog posts with my content on other web sites, such as my Flickr photos and my ma.gnolia links. This is, of course, the joy of API in action, and it made me think differently about how I was tagging my stuff.

Part of that thought was the inclusion of tags such geo:lat=50.382 which enabled me to associate a physical location with a blog post. Called triple tags at the time, we now know this format as machine tags thanks to Flickr. A year on, and other services such as Upcoming and are encouraging their users to tag Flickr photos with machine tags such as upcoming:event=144002 and lastfm:event=97947 thereby associating photos with events and gigs, and enabling these services to illustrate content with relevant photography.

In terms of searching and API goodness, I believe Flickr is still the leader in terms of what can be done with machine tags. When tagging, the format is crucial and must be of the form namespace:predicate=value. Flickr recognises the three parts and stores them separately, thus enabling one to search within any namespace, for any predicate and/or for any value. Powerful stuff, as explained in Rev Dan Catt’s post earlier this year.

Anyone can invent any namespace and nomenclature. For example, I have tagged this photo with clagnut:blogid=1900 to explicitly associate it with this blog post. Flickr recognised the machine tag and now I can use the API to search for any photo tagged with the clagnut namespace.

The ability for anyone to create a namespace opens up an interesting future as we begin to see patterns and conventions emerge: amazon:asin=B000AA4I1M anyone? Which brings me to the point of this post. This time last year I was tagging photos and posts which discussed books in the following manner isbn=0713998393. In and of itself this works fine, but it is not a valid machine tag, which means we cannot make use of the afore-mentioned API goodness within Flickr (and where Flickr is leading so others will follow). We therefore need a triple-tag version of the ISBN tag, and here’s my suggestion: iso:isbn=0713998393. ISBN is a standard recognised by the International Organisation for Standardization (ISO) so I thought it made a certain sense for ISO to be the namespace. Other standardised entities could be tagged in a similar way, such as iso:issn=15340295.

Is an ISO namespace something likely to be used in the future? Is it fatally flawed, and if so how would you suggest machine tagging ISBNs instead? Discuss.

Update Further to Peter Firminger’s comment it seems might become a good place to propose and develop define new namespaces.