The current state of interoperability of advanced directive information is almost entirely the exchanged of scanned paper documents. The PACIO-IG specification says:

> Advance directive documents may take several forms including scanned PDF documents, CDA documents and native FHIR documents. This guide defines interoperability to support any number of types, though focuses on native FHIR documents.

The approach being taken in this specification, as noted, is to focus on creating, net-new, discrete, and complex "native FHIR documents". Defining this aspirational, perfect state is entirely worthwhile; however, it is definitely not the current state, and due to the size and complexity of the currently being defined native FHIR documents is not even near-term nor mid-term. For example, your notary and witness sections seem to even aspire to replace current state-level legislation requiring "wet" signatures. We fear that by only specifying the perfect end-state, you will damage the industry's movement towards interoperable exchange of ADI information as it currently exists in the real world.

You should split off the specific exchange of "scanned PDF documents" and/or "CDA documents" and define as absolutely simple exchange of a DocRef and Binary, and then also continue your aspirational, perfect-world, discrete ADI exchange.