http://hl7.org/fhir/StructureDefinition/questionnaire-baseType|5.2.0

This identifies the underlying type in a profile, when a questionnaire is generated from a profile.
{
  "description": "This identifies the underlying type in a profile, when a questionnaire is generated from a profile.",
  "package": "hl7.fhir.uv.extensions.r5@5.2.0",
  "date": "2013-07-04T00:00:00Z",
  "derivation": "constraint",
  "publisher": "HL7 International / FHIR Infrastructure",
  "fhirVersion": "5.0.0",
  "jurisdiction": [ {
    "coding": [ {
      "code": "001",
      "system": "http://unstats.un.org/unsd/methods/m49/m49.htm"
    } ]
  } ],
  "name": "QBaseType",
  "mapping": [ {
    "uri": "http://hl7.org/v3",
    "name": "RIM Mapping",
    "identity": "rim"
  } ],
  "abstract": false,
  "type": "Extension",
  "experimental": false,
  "resourceType": "StructureDefinition",
  "fhirversion": null,
  "title": "Questionnaire Base Type",
  "versionAlgorithmCoding": null,
  "extension": [ {
    "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
    "valueCode": "fhir"
  }, {
    "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm",
    "valueInteger": 3
  }, {
    "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
    "valueCode": "trial-use"
  }, {
    "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics",
    "valueCode": "can-bind"
  } ],
  "status": "active",
  "id": "e53c565d-cde7-5b90-b83e-4878a52d1f68",
  "kind": "complex-type",
  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-baseType",
  "identifier": [ {
    "value": "urn:oid:2.16.840.1.113883.4.642.5.1255",
    "system": "urn:ietf:rfc:3986"
  } ],
  "context": [ {
    "type": "element",
    "expression": "Questionnaire.item"
  }, {
    "type": "element",
    "expression": "ElementDefinition"
  } ],
  "versionAlgorithmString": null,
  "fhir_id": null,
  "version": "5.2.0",
  "contact": [ {
    "telecom": [ {
      "value": "http://www.hl7.org/Special/committees/fiwg",
      "system": "url"
    } ]
  } ],
  "baseDefinition": "http://hl7.org/fhir/StructureDefinition/Extension"
}