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What is a CQL library?

A CQL library is a file that contains CQL logic, such as expressions, definitions, functions, and value sets. Libraries are available in formats such as .cql, .xml, and .json. Each measure includes a primary CQL library that defines the logic used for the measure populations. 

eCQMs and dQMs can also use shared libraries. Shared libraries allow multiple eCQMs, dQMs, and in some cases Clinical Decision Support (CDS) artifacts, to reuse common definitions and functions, such as Hospitalization. Reusing libraries helps reduce duplication and supports more efficient measure development and implementation.

For more information, see the Libraries section of the CQL Developer's Guide.

Last Updated: Sep 29, 2026

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