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Type:
Technical Correction
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Resolution: Persuasive
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Priority:
Medium
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FHIR Core (FHIR)
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R4
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Modeling & Methodology
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Datatypes
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Correction
The following description/expression of the "drt-1" constraint for Duration data type don't match at: https://www.hl7.org/fhir/datatypes.html#QuantityVariations
Description: "There SHALL be a code if there is a value and it SHALL be an expression of time. If system is present, it SHALL be UCUM."
Expression: "code.exists() implies ((system = %ucum) and value.exists())"
Based the expression, it's valid to have a value, but no code, which conflicts with the description. It seems like the expression instead should be more like the expression for Age, which starts like: "(code.exists() or value.empty()) and ...".