$10 / year

This dataset shows the use of expression logic within Fast Healthcare Interoperability Resources (FHIR) resources using expression languages such as FHIRPath and Clinical Quality Language (CQL). In general, the use of expressions involves the following elements:

– Description – A natural language description of the logic.
– Language – The expression language used to represent the logic.
– Expression – The expression itself in the identified language.


The general pattern is used to represent expression logic throughout the resources in the Clinical Reasoning module and allows expression logic to be represented at different levels:

– Unstructured – The logic in this case can be communicated using natural language without the expectation that it is computable. This information is useful for communicating the intended dynamic semantics to environments that do not support computable evaluation.
– Structured – The logic is specified as a computable expression in a formal language. This information is useful for communicating the logic to environments that are expected to support the computation.
– Mixed – The logic in this case is communicated using both a natural language description, as well as a computable expression in a formal language. This information is useful for communicating to environments that may support the computation as well as to environments that do not, or to environments that support the computation but desire human-readable information to more easily understand the logic.

For example, the Dynamic Value element of the Activity Definition and Plan Definition resources contains these three elements – description, language, and expression – directly. However, for resources that do not define these elements, extensions are provided to enable expression information to be associated with any FHIR resource.

Date Created


Last Modified




Update Frequency


Temporal Coverage


Spatial Coverage

United States


John Snow Labs; Health Level Seven International;

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Source License Requirements


Source Citation



FHIR, HL7, Medical Terminology, Processes Data, Processes Information, Processes Documentation, Health Information Exchange, Electronic Health Records, FHIR Smart, Smart on FHIR

Other Titles

FHIR Expression Resource, Electronic Health Records Exchange Through FHIR

Concept_NameName of the concept in the FHIR structurestringrequired : 1
Computer_Ready_NameA Computer-ready name (e.g. a token) that identifies the structure - suitable for code generation. Note that this name (and other names relevant for code generation, including element & slice names, codes etc) may collide with reserved words in the relevant target language, and code generators will need to handle this.string-
TypeThe type the structure describes.string-
Dollar_RefThe "$ref" string value contains a Uniform Resource Identifier (URI) which identifies the location of the JSON value being referenced.string-
DescriptionA free text natural language description of the structure and its usestring-
ItemsThe value of the keyword should be an object or an array of objects. If the keyword value is an object, then for the data array to be valid each item of the array should be valid according to the schema in this value.string-
EnumThe value of the keyword should be an array of unique strings. The data object to be valid should contain all properties with names equal to the elements in the keyword value.string-
Concept NameComputer Ready NameTypeDollar RefDescriptionItemsEnum
Expressionid#/definitions/stringUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
ExpressionextensionarrayMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension there is a set of requirements that SHALL be met as part of the definition of the extension.{'$ref': '#/definitions/Extension'}
Expressiondescription#/definitions/stringA brief natural language description of the condition that effectively communicates the intended semantics.
Expression_description#/definitions/ElementExtensions for description
Expressionname#/definitions/idA short name assigned to the expression to allow for multiple reuse of the expression in the context where it is defined.
Expression_name#/definitions/ElementExtensions for name
ExpressionlanguageThe media type of the language for the expression.['text/cql' 'text/fhirpath' 'application/x-fhir-query']
Expression_language#/definitions/ElementExtensions for language
Expressionexpression#/definitions/stringAn expression in the specified language that returns a value.
Expression_expression#/definitions/ElementExtensions for expression
Related Data Packages