HL7 is a healthcare application protocol accredited as a Standard by the American National Standards Institute (ANSI). This Standard covers implementation of pathology orders and results using HL7 Version 2.3.1 protocol, for communication between health service providers and pathology providers, within and between Australian health care settings. The Standard includes the data segments and data elements that are mandatory (required), optional or conditional (required, based on a condition), and relevant usage notes in the Australian health environment. The Standard provides consistent use of data definitions as well as commentary and references to the International Organization for Standardization (ISO), the National Health Data Dictionary (NHDD), the National Association of Testing Authorities Australia (NATA) and The Royal College of Pathologists of Australasia (RCPA).