Healthcare in the Age of Interoperability: The Promise of Fast Healthcare Interoperability Resources.

The first article of this series (see "About This Series") mentioned that, after the success of its new messaging standard for electronic health record (EHR) systems, Health Level 7 (HL7) found it difficult to develop and widely deploy a standard for the rich representation of clinical data for use in patient care. This was due, in large part, to the complexity of medicine and the resulting complexity of the clinical terminologies developed to represent it.