In general EHR classification, recognised in both XDS & FHIR, there an assumption that the type of document is orthogonal to the role of the creator, so for instance a "report" could generated by a doctor or physio, or a "prescription" could be generated by a doctor or nurse etc. However it is reasonable for those trawling though extensive notes to wish to identify the source of the documents - e.g. to locate "physio notes" or "nursing notes" etc. In the XDS metadata scheme, the "author" attribute has a "role" which can be used for this (not ideal, as it is not server searchable and needs client side filtering, but at least it is there!). When doing an XDS <=> FHIR mapping I cannot identify any equivalent in the DocumentReference resource. The closest I can find are the qualifications of the practicationer - which is rather indirect and in any case a property of the practitioner not of the encounter/document or the PractitionerRole which has the same limitations. Am I missing something? What should be the quick way to retrieve only references to documents created by physiotherapsists?