This code system http://terminology.hl7.org/CodeSystem/measure-supplemental-data-example defines the following codes:

Code Display Definition
age Age Age Supplemental Data.
gender Gender Gender Supplemental Data .
ethnicity Ethnicity Ethnicity Supplemental Data .
payer Payer Payer Supplemental Data.
<status value="draft"/> <experimental value="false"/> <publisher value="Clinical Quality Information Workgroup"/> <description value="Identifier supplemental data in a population for measuring purposes."/> <caseSensitive value="true"/> <valueSet value="http://hl7.org/fhir/ValueSet/measure-supplemental-data-example"/> <content value="complete"/> <concept> <code value="age"/> <display value="Age"/> <definition value="Age Supplemental Data."/> </concept> <concept> <code value="gender"/> <display value="Gender"/> <definition value="Gender Supplemental Data ."/> </concept> <concept> <code value="ethnicity"/> <display value="Ethnicity"/> <definition value="Ethnicity Supplemental Data ."/> </concept> <concept> <code value="payer"/> <display value="Payer"/> <definition value="Payer Supplemental Data."/> </concept> </CodeSystem>