New EHR reference model draft

Dear all,

a new draft of the openEHR EHR reference model is available at http://www.deepthought.com.au/health/openEHR/rm/ehr_rm_3_3_1.pdf.

While there is still a lot of work to do, the models are solid enough to start being used. The main change from previous versions is the addition of a Change_control cluster to define the semantics of versioning generically, and the use of these semantics for versioning of Transactions.

All comments welcome.

- thomas beale