https://s3.amazonaws.com/IGG/EHR.pdf When the individuals involved are a licensed professional and a patient, the Logical Model (p62) makes almost no sense at all. The EHR could be compiled from source and patient owned as long as: (1) the licensed professional's claims can be verified by the patient against their issuers (2) the licensed professional can put a digital signature on a detailed log entry created by the EHR (3) the timestamped hash of the log entry can be put on a distributed public ledger (4) the licensed professional may keep a copy of their log entry and the timestamp proof in case of dispute where the patient "loses" their copy. An effective individual-centric solution depends on substitutability and therefore standards. There are standards being worked on for many of these steps: (1) W3C Verifiable Claims https://www.w3.org/2017/vc/charter (2) Rebooting Web of Trust Decentralized Identifier (DID <https://github.com/WebOfTrustInfo/rebooting-the-web-of-trust-fall2016/blob/master/draft-documents/DID-Spec-Implementers-Draft-01.pdf>) is being implemented by 4 separate groups (3) Chainpoint http://www.chainpoint.org/ and Open Timestamps <https://petertodd.org/2016/opentimestamps-announcement> are being combined in Rebooting Web of Trust (4) is just a personal data store like Dropbox The HIE of One Use Case and reference implementation http://hieofone.org/ is in the process of implementing this whole stack. (a) The patient-controlled EHR is done. (b) The patient-controlled controller of the EHR and other resources is a personal UMA AS and is done. (c) The physician's DID and secure signature are initially demonstrated using uPort <https://www.youtube.com/watch?v=FNlAkGauIdw&list=PLn9P7BiqUmmjk09q4I57cvPwysvsScm1p&index=6> and being upgraded and integrated. (d) Verifiable Claims is not yet implemented. The Use Case paper <https://www.healthit.gov/sites/default/files/7-29-poweringthephysician-patientrelationshipwithblockchainhealthit.pdf> won an ONC Blockchain Health prize. (e) Timestamps of the physician's interaction with the EHR are not yet implemented. I believe this shows a licensed individual writing a prescription or curating a patient-centered longitudinal health record in the absence of any particular federation or trust framework. Adrian -- Adrian Gropper MD