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

This extension will only be processed while extracting a resource based on a parent item (or root) using either the [definitionExtract](/sdc-structuredefinition-sdc-questionnaire-definitionextract-intro) or [itemExtractionContext (legacy)](/sdc-structuredefinition-sdc-questionnaire-itemextractioncontext-intro) extension. It is <strong>NOT</strong> valid to specify an extractDefinitionValue prior to (and outside the hierarchy) where the corresponding extractDefinition is found.

It is used to define the value of a property on the resource being extracted, without requiring an item/answer in the questionnaire response (typically for fixed, or derived/calculated values).

The property is based on the value in the `definition` property, where the prefix (before the `#`) must exactly match the profile's canonical URL from the extraction context in a parent item/root.

Additional details on the use of this extension can be found on the [Data Extraction](/sdc-extraction#definition-based-extraction) page.