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CQL - Clinical Quality Language

Explore these resources to get an overview of CQL­ and learn how to implement CQL from experts.

CQL Tools for Implementers

CQL-to-ELM Translator Reference Implementation

The Health Level Seven International® (HL7®) CQL specification defines both a high-level, author-friendly syntax for expressing clinical knowledge, and a machine-friendly, syntax-independent canonical representation of clinical knowledge called ELM. The design of the high-level ELM syntax is to support measure and decision support authors, while the design of the canonical representation is to support point-to-point sharing and machine processing applications.

CQL Resources for Authors

CQL Formatting and Usage Wiki
QDM-based CQL Style Guide (v9)

QDM-based CQL Style Guide (v9) provides guidance to measure developers for authoring measure expressions and using functions, libraries, and definitions for calendar year 2026 reporting. Modifications to the QDM-based CQL Style Guide include references to the HL7 CQL standard, the HL7 CQL-based Health Quality Measure Format (HQMF) Implementation Guide, and input from standards owners and measure developers to refine CQL expression. The purpose of the QDM-based CQL Style Guide is to standardize the expression of measure concepts across eCQMs and define a uniform “look and feel” to eCQM logic using CQL. The QDM-based CQL Style Guide focuses on a set of common best practices implemented across CQL-based eCQMs in CMS quality reporting programs. The QDM-based CQL Style Guide also promotes the use of consistent language within the framework of CQL, including libraries, aliases, definitions, functions, and guidance on other conventions, such as operator precedence. Measure stewards and measure developers who are developing or specifying eCQMs for future inclusion in CMS programs should align with these best practices.

Last Updated: Jun 17, 2025