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

### Scope and Usage

This profile adds additional constraints and extensions to the base [SDC Base Questionnaire Profile](/sdc-structuredefinition-sdc-questionnaire-intro) that support generating and potentially partially populating a questionnaire response using existing FHIR resource data. This profile identifies which core elements and extensions must be supported when using the [Expression-based](/sdc-populate#exp-pop) population mechanism and highlights other elements that, while not required, may be relevant to the questionnaire response population use-case. Further information on how this use-case is implemented as well as guidance on the elements and extensions included in the profile can be found on the [Questionnaire Population](/sdc-populate) page.