Health Level Seven (HL7) is the American National Standard for clinical information. It is an application protocol for electronic data exchange in health care environments. HL7 Version 2.2 covered electronic health care messaging within hospitals. Australian Standard AS 4700.1-1997 covers the implementation of HL7 Version 2.2 for admission, discharge and transfer of patient information within Australian public and private hospitals. This Standard provides an important foundation for the building of most clinical health care messages. HL7 Version 2.3 is an important foundation for the building of most clinical health care messages. HL7 Version 2.3 is an important new Standard. It extends outside hospitals to the wider heath care community environment. AS 4700.1-1997 also applies to HL7 Version 2.3.