Message received from RIXML.org contact us page:
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Hello,

Can you tell me whether the newly-release 2.1 spec is backwards compatible
at the schema level with 1.0, and if not, which aspects we'd need to change?

Thanks and best regards,
James Forrester
Moody's Investors Service

Thanks for writing to us, James. No, RIXML 2.1 is not backward-compatible with RIXML 1.0. When we developed 2.0, we considered these factors: (1) The extent to which backward-compatibility would limit where we could take RIXML. (2) The estimated installed base of software that, at the time, relied on RIXML 1.0. The membership chose to set aside backward-compatibility as a goal when moving from 1.0 to 2.0. As RIXML adoption progresses throughout the industry, however, the priority of backward-compatibility increases.

Several people have asked us about a document that would outline the changes between 1.0 and 2.0 -- a release notes document. Regretably, we do not currently have such a document available. However, we are working on a project to supply one in the future. Thank you for bearing with us on this matter.