What is HL7?

• Full form of HL7: Health Level Seven
• Accredited standards to share clinical and administrative data
• Promoted by Health Level Seven Inc. (USA) Ann Arbor, MI (USA)
• Freely available without licenses or license fees 
• Copyrighted for accuracy and integrity
• HL7 message format: human readable ASCII
• HL7 message  -> consists of segments
• Over 120 different segment types are available
• Segments are separated by line feeds (\r or 0x0D)
• A segment begins with a three letter name such as MSH
• Segment examples: MSH (Message Header), PID (Patient Info)
• Segment -> consists composites (or fields)
• Composites are separated by | characters (or \F\)
• Composites may contain other composites (sub-composites or sub-fields)
• Sub-fields are separated by ^ characters (or \S\)
• Sub-composites may contain other composites (sub-sub-composites or sub-sub-fields)
• Sub-sub-fields are separated by & characters (or \T\)
• HL7 website: http://www.hl7.org/
• HL7 on Wikipedia: http://en.wikipedia.org/wiki/HL7
• HL7 glossary of terms: http://www.hl7.org/ehr/documents/public/documents/Glossary%20of%20terms.pdf