To make it easier to send and receive health-care information, the HL7 organization has defined a standard that specifies what types of HL7 messages can be sent, what segments can be included in these messages, and what fields can be included in their segments.
The HL7 standard is constantly evolving. To date, the HL7 committee has released nine versions of the HL7 standard:
A revised version of the HL7 standard, version 3.0, has been in ongoing development since 1997, but is not yet in common use.
The following sections provide more information about these versions of the HL7 standard.