This code system http://hl7.org/fhir/condition-questionnaire-purpose defines the following codes:

CodeDisplayDefinition
preadmit Pre-admitA pre-admit questionnaire.
diff-diagnosis Diff DiagnosisA questionnaire that helps with diferential diagnosis.
outcome OutcomeA questionnaire to check on outcomes for the patient.
<status value="active"/><experimental value="false"/><date value="2021-01-05T10:01:24+11:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="The use of a questionnaire."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/condition-questionnaire-purpose"/><content value="complete"/><concept><code value="preadmit"/><display value="Pre-admit"/><definition value="A pre-admit questionnaire."/></concept><concept><code value="diff-diagnosis"/><display value="Diff Diagnosis"/><definition value="A questionnaire that helps with diferential diagnosis."/></concept><concept><code value="outcome"/><display value="Outcome"/><definition value="A questionnaire to check on outcomes for the patient."/></concept></CodeSystem>