---
type: "sdc-page"
title: "SDC: StructureDefinition-sdc-questionnaire-itemPopulationContext-intro"
source: "sdc/input/pagecontent/StructureDefinition-sdc-questionnaire-itemPopulationContext-intro.xml"
---
# SDC: StructureDefinition-sdc-questionnaire-itemPopulationContext-intro

Additional details on the use of this extension can be found on the [Using Expressions](/sdc-expressions#itemPopulationContext) and [Questionnaire Population](/sdc-populate#expression-based-population) pages. For explanation of how `itemPopulationContext` defines the population scope for an item, refer to the [Expressions page - itemPopulationContext](/sdc-expressions#itemPopulationContext) section.