ABSTRACT
Unlike digital imaging and communications in medicine (DICOM), health level 7 (HL7) is a closed commercialised standard maintained by the Health Level Seven International Organisation, and until late 2013 was completely unavailable for quick review on the internet without paid membership of the organisation. HL7 itself was a standard born out of the need for connectivity and integration to enable the exchange of textual healthcare information to the benefit of patients. HL7 messages are text strings, formatted in very specific, defined, repeatable ways. Each message has every possible 'field' either filled or left empty, separated by specific characters (known as delimiters). All possible data types for particular fields are defined by the standard. Version 2 HL7 messages are intended for machine use and interpretation, rather than human manipulation. HL7 messages comprise separate segments, each prefixed with a standard code to indicate what type of information they hold.
