BASICS HL7 Lingo
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ike any technology, HL7 uses a glossary of specific terms that have specific meaning. While an interface engine alleviates the need to directly integrate with all of these concepts, understanding them will help you know what the HL7 engine is actually doing. Envelope: Each communication from one system to another is contained in a block of data. This block of data (Envelope) could contain one or more messages. Message: A message is a set of data that is logically related (for instance, about a specific patient encounter or hospital admission). A message is bounded by its type (Message Type) and contains a number of (Segments). Message Type: A message type is the definition of the structure of a communication and provides rules for what data sections (Segments) are required, which are optional, and the order of the data. The order of the data in a message is important as one section (Segment) can have different meanings depending on where it is in the message. Messages are usually referred to by their message type and event type, for example: an ADT^A01 is an ADT message with an event type of A01 which means that this is an Admission, Discharge, or Transfer type message (ADT) and is signaling the event that a patient was Admitted (A01). Event: Events allow a message type to have slightly different meaning as described above. Events are related to the message type and an important part of the standard. The same message structure can be used to signal different types of events. The same basic data is needed to admit and discharge a patient with only small differences. HL7 has evolved over many years and new events have been added to the standard that weren’t there in previous versions. For instance, an ADT A01 (ADT Patient Admit) and an ADT A08 (ADT Patient Data Update) were initially defined as different message types, but later combined. So, a message that comes in as