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

### Scope and Usage

Value Sets are used to define possible answer choices in a re-useable cross-questionnaire (and other data structure) manner. They reference codes from one or more [Code Systems](/sdc-structuredefinition-sdc-codesystem-intro) which might be locally-defined or might be standard international terminologies like LOINC or SNOMED CT or regional code systems for drugs, billing codes, etc. The use of standardized codes is useful when data needs to be populated into the questionnaire or extracted from the questionnaire for other uses. It is also helpful when the set of possibilities is highly dynamic - for example drug codes where the set of available codes might change daily or weekly.

This profile sets expectations for use of the [ValueSet]({{site.data.fhir.path}}valueset) resource when used as a source for answers to questions in a Questionnaire. It identifies which core elements and extensions must be supported and highlights other elements that, while not required, may be relevant to the Questionnaire use-case.

For systems where discovery of Value Set is important, implementers are encouraged to also comply with the [CRMI Shareable ValueSet](http://hl7.org/fhir/uv/crmi/StructureDefinition/crmi-shareablevalueset) profile.