2. A Validator
There is a validator that can be used to check the validity of a newsfeed that allegedly conforms to one of these specifications. This validator is at http://feedvalidator.org/
I have been using this validator to check out the validity of the RSS 1.0, RSS 2.0, Atom 0.3 and Atom 1.0 newsfeeds produced by OXITEMS (a newsfeed generation system that is used by departments and colleges at the University of Oxford).
If you attempt to validate an Atom 0.3 newsfeed using this validator, it will report the newsfeed is an obsolete version. It says that early adopters of the Atom format should upgrade their feed to the latest version of the specification.