Current spec does not allow URI-style terminology ids; various solutions appear possible:
add extra field to CODE_PHRASE (probably not a good solution)
relax TERMINOLOGY_ID regex to allow URIs (at least ':', ... more chars?)
The current regex described in https://openehr.org/releases/BASE/latest/docs/base_types/base_types.html#_syntaxes is...
terminology_id = name-str, [ '(', name-str, ')' ] ;
name-str = letter, { letter | digit | '_' | '-' | '/' | '+' } ;
...and thus does not allow URIs
Additionally create a mapping table for openEHR of all terminology namespace names like 'SNOMED-CT', 'loinc'.