We agree that the FHIR documentation is unclear about where Parameters can and cannot be used. The resolutions of Jiras submitted in 2020 by Josh Manel ( FHIR-26368 ) and Vassil Pytchev, the commenter ( FHIR-26390 ) clarify that Parameters may be used as a message focus. Both issues were resolved as non-substantive clarifications, which we understand as indicating that this does not represent a new use, but instead a clarification to documentation. To the numbered suggestions in the comment: 1 and 2. An important goal of the IG is to enable all parties involved in specialty medication fulfillment to participate in the exchanges. As a result, the guide includes a REST-only implementation option as well as a messaging-based option for a large portion of pharmacies that today rely on network intermediaries. The messaging approach supports network routing, which is why we chose that approach over use of operations. 3. We believe the messaging structures in the guide include the resources needed to accomplish the intent of each exchange.