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

Additional details on the use of this extension can be found on the [Questionnaire Population](/sdc-populate#expression-based-population) page. For information on how `contextExpression` provides relevant information to guide user input, refer to the [Expressions page - contextExpression](/sdc-expressions#contextExpression) section.