And my sharp eyed colleague has just spotted another on:
27) There is a mistake in the example in section 3.1
<r:RDF xmlns:r="
http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:a="
http://www.w3.org/2000/10/annotation-ns#"
xmlns:d="
http://purl.org/dc/elements/1.1/"
xmlns:tr="
http://www.w3.org/2001/03/thread#"
xmlns:h="
http://www.w3.org/1999/xx/http#"
xmlns:rt:"
http://www.w3.org/2001/12/replyType">
The last xmlns declaration is missing a '#' after 'replyType'. Actually,
this particular xmlns declaration defines a prefix that is not used in the
example and could therefore be deleted entirely.