HL7 Arden Syntax for Medical Logic Systems, Edition 3.0

This standard defines a syntax for creating and sharing computerised health knowledge bases. The scope of this standard is limited to knowledge bases that can be represented as a set of discrete modules, each referred to as a Medical Logic Module (MLM). Each MLM contains sufficient knowledge to make a single decision. Clinicians, knowledge engineers, administrators and others can use the syntax to implement clinical decision support solutions to help improve quality and safety of care.

The main change in this version of the standard compared with the previous version is the addition of syntax to support Health Level 7’s Fast Healthcare Interoperability Resources (FHIR) standards.

Main sections:

· Terminology

· Significance and use

· MLM format

· Slot descriptions

· Structured slot syntax

· Data types

· Operator descriptions

· Logic slot

· Data slot

· FHIR-enabled data access

· Action slot

· Evoke slot

· Annex A1: Formal representation

· Annex A2: Reserved words

· Annex A3: Special symbols

· Annex A4: Operator precedence and associativity

· Annex A5: Format specification

· Annex A6: Objects in Arden syntax

· Appendix X1: Language and country codes for HL7 international affiliate countries

· Appendix X2: Sample MLMs

· Appendix X3: Summary of changes