Given that these numbers are individually sourced from customers, customers own their own data, and all interchange is P2P--there's not a good way to really cou

Given that these numbers are individually sourced from customers, customers own their own data, and all interchange is P2P--there's not a good way to really count. Customers own their range of member-numbers as well. Plus, the whole thing about identity is even more difficult, you can't go by name, SSN, and DOB alone. As far as I know, HL7 is mostly used between internal systems within an organization. For sending actual patient data, allergies, conditions, CCDA is usually used for communication with non-Epic EMRs belonging to other organizations. As an aside, CCDA and HL7 don't support rich data well, so they usually end up as base64 encoded PDFs.