This value set includes codes based on the following rules:

• Include these codes as defined in urn:oid:2.16.840.1.114222.4.5.274 version 20200526

  Code	Display
  FDD_A_57	Maybe

• Include these codes as defined in http://terminology.hl7.org/CodeSystem/v2-0532 version HL7 v2.5

  Code	Display
  N	No
  Y	Yes

• Include these codes as defined in http://terminology.hl7.org/CodeSystem/v3-NullFlavor version 20090501

  Code	Display
  UNK	Unknown