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The openEHR approach was to make it so the data could be created, signed, stored and shared intact, with no regeneration of the data with interspersed things like policies and sensitivity. With the 13606 approach, you are really forced to reprocess your incoming data into a different form to create an EHR whose data can be properly versioned, signed etc, or if you want to directly store the 13606 data form, put up with continual revisions on the data whenever a policy / sensitivity preference is changed.
Entry
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classes
The lower level structures used in openEHR are more complex than in 13606, which just uses a CLUSTER/ELEMENT structure under a single ENTRY type. openEHR on the other hand has 6 concrete Entry class descendants: OBSERVATION, EVALUATION, INSTRUCTION, ACTION, ADMIN_ENTRY, GENERIC_ENTRY. A simplification in the data structure classes used within the openEHR Entry classes will help to bring openEHR and 13606 together - see below. One basic strategy to bring these classes together at the Entry level is for the openEHR types to include factory routines that generate standard CLUSTER/ELEMENT structures from the native openEHR structures.
Data structure classes
This page discusses possibilities for simplifiying openEHR's more sophisticated classes.