Encounter.indication needs to be constrained to only Condition or Procedure (from any reference). PA Conference Call 26 August 2015: The reason and indication properties are actually the one thing, so will collapse into the 1 property called reason which can be either: Procedure, Condition or codeableConcept. This property will be changed to permit multiple values (cardinality 0..*) (Technical correction, can't do the above, so remains 2 properties - reason and indication - that are multi-cardinality) A standard extension (positive int) can be used to indicate the sequence of diagnosis (1 = primary). Note that we would like to get implementer feedback on this issue to see if a more detailed aproach is required.