The HL7 specification defines specific message segments for specific kinds of clinical data. It defines the events which should trigger different types of messages. It defines a minimal protocol to be used to transmit messages (which nearly everyone uses). It is not at all analogous to JSON nor XML. HL7 3.x isn't just XML-ish; it allows the use of standard XML (in addition to the classic delimited format).<p>Again, I don't know of any hospital system which doesn't offer one or more specific HL7 interfaces (ADT, results, billing, etc.). It is very common for hospitals to have clinical document repositories which accept multiple formats.<p>While I agree with your general sentiments about the state of the industry, I don't believe the problem to be a lack of standards or opportunities for integration. Additionally, the incentives you speak of will happen at the end of the year. See my comment elsewhere about CCD/CDA (CDA is part of the HL7 standards). ARRA funds will be available at the end of the year for systems which implement HITSP standards (I'm oversimplifying a bit).