We will make clear that dataAbsentReason is supported in HRex (and in DaVinci IGs in general) - i.e. where an element is marked as minOccurs=1 but the data is not available and there is still a need to (and value in) sending the instance.  I.e. Just because an element is minOccurs=1, that doesn't necessarily mean there will always be a 'value' present.  (However, if minOccurs = 1, the sending system must provide a reason why no data is present if it can't send a value.)