Health Level Seven (HL7) is one of several American
National Standards Institute (ANSI) accredited Standards
Developing Organizations, operating in the healthcare
arena worldwide. ("Level Seven" refers to the highest
level of the International Standards Organization's (ISO)
communications model for Open Systems
Interconnection (OSI) —the application level.) According
to Mauro Regio (2005), the HL7 vision is to create an
infrastructure for interoperability in the healthcare
domain. HL7 uses the reference information model (RIM)
to derive domain specific information models and refine
them into HL7 message specifications.