Notes on digital signatures in openEHR.
Canonical Format
In order to support digital singing of compositions, a canonical format for a composition instance must be specified.
This could be something like "use the XML ITS format" - though this would still be ambiguous - a canonical representation of the XML would need to be chosen.
Alternatively, a very simple "canonical ITS" could be written that has no ambiguity (perhaps a simple hierarchy format like JSON, YAML etc - I don't think these are per-se particularly suitable but maybe something similar could be specified).
The format which I currently prefer is still the dADL syntax from ADL, since it gives an unambigous serialisation of any object structure. We have this already working inside the Eiffel ADL parser. - thomas beale
If the canonical format is primarily intended for machine readability and digital signatures, then JSON is probably a good choice due to it's:
Designing a YAML ITS for openEHR would be a good thing also (for other purposes - perhaps e.g. long time archival of EHRs), but for use in digital signatures I'd suggest using JSON.