We've been having a number of discussions among our spec leads here
around backward compatibility and the rules that we've been implicitly
following in our various Java EE releases. Nigel Deakin, the JMS
spec lead, has taken the initiative to write them down, and Bill
has linked them here:
http://java.net/projects/javaee-spec/pages/CompatibilityRequirements
Please let me know if you have any questions.
-Linda