There’s been a fair amount of interesting commentary about metadata and such in the last few weeks. From Don Park’s post on Emergent Markup to Jon Udell’s posts on RDF and RSS to the release of O’Reilly’s Practical RDF with its companion website.

Dare Obasanjo has just offered his “turing test” for a model that allows for freely mixing XML-namespaced content in a single document:

RDF is definitely not that model. Here’s my pair of Turing tests for when we have that model.

1. I can take a vanilla XSLT processor and pass it a stylesheet with EXSLT extension elements which my XSLT processor automatically learns how to process as valid stylesheet instructions.

2. I can take a vanilla W3C XML Schema processor and pass it a schema with embedded Schematron assertions which it automatically learns how to use to validate an input document in addition to using the W3C XML Schema rules.

RDF may not be the model for that, but I bet that RDF could be used to define the model. Something to think about…

UPDATE:
You could add Ted Leung’s dilemma about extendable RSS aggregators to the test…