This is the 2018 May Ballot Version of Clinical Quality Language STU 3
For a full list of available versions, see the Directory of published versions 
.
| Clinical Decision Support Work Group | Maturity Level: 4 | Ballot Status: STU 3 |
HL7 Standard: Clinical Quality Language Specification, Release 1 STU3 (CQL 1.3)
May 2018
HL7 STU Specification
Clinical Quality Language (CQL) is a high-level, domain-specific language focused on clinical quality and targeted at measure and decision support artifact authors.
In addition, this specification describes a machine-readable canonical representation called Expression Logical Model (ELM) targeted at implementations and designed to enable sharing of clinical knowledge.
The organization of this specification follows the outline of the perspectives discussed in the Approach section—conceptual, logical, and physical. Below is a listing of the chapters with a short summary of the content of each.
Chapter 1 – Introduction provides introductory and background material for the specification.
Chapter 2 – Author’s Guide provides a high-level discussion of the Clinical Quality Language syntax. This discussion is a self-contained introduction to the language targeted at clinical quality authors.
Chapter 3 – Developer’s Guide provides a more in-depth look at the Clinical Quality Language targeted at developers familiar with typical development languages such as Java, C#, and SQL.
Chapter 4 – Logical Specification provides a complete description of the elements that can be used to represent quality logic. Note that Chapters 2 and 3 describe the same functional capabilities of the language, and that anything that can be expressed in one mechanism can be equivalently expressed in the other.
Chapter 5 – Language Semantics describes the intended semantics of the language, covering topics such as data layer integration and expected run-time behavior.
Chapter 6 – Translation Semantics describes the mapping between CQL and ELM, as well as outlines for how to perform translation from CQL to ELM, and vice versa.
Chapter 7 – Physical Representation is reference documentation for the XML schema used to persist ELM.
Appendix A – CQL Syntax Formal Specification discusses the ANTLR4 grammar for the Clinical Quality Language.
Appendix B – CQL Reference provides a complete reference for the types and operators available in CQL, and is intended to be used by authors and developers alike.
Appendix C – Reference Implementations provides information about where to find reference implementations for a CQL-ELM translator, a CQL Execution Framework for JavaScript, and other related tooling.
Appendix D – References
Appendix E – Acronyms
Appendix F – Glossary
Appendix G – Formatting Conventions
Appendix H – Timing Interval Calculation Examples
Appendix I – FHIRPath Function Translation