The RFC 4685 define an xml namespace with "http://purl.org/syndication/thread/1.0". An HTTP GET http://purl.org/syndication/thread/1.0 answer HTTP/1.x 302 Found Location: http://www.ietf.org/internet-drafts/draft-snell-atompub-feed-thread-12.txt
which redirect to http://www.ietf.org/internet-drafts/draft-snell-atompub-feed-thread-12.txt which answer HTTP/1.x 404 Not Found Please fix this issue and make http://purl.org/syndication/thread/1.0 redirecting to http://www.ietf.org/rfc/rfc4685.txt or http://tools.ietf.org/html/rfc4685 or http://www.rfc-editor.org/*4685*.