Most of the IG doesn't really make use of workflow - asking for an order to be fulfilled - though the CommunicationRequest bit does a little bit.  This IG will be pointing to a new section in HRex that speaks to the many mechanisms that FHIR defines for performing data sharing and will identify a specific subset from that set of options and will describe how the decision was taken to select those specific exchanges.  Also, the HRex IG will refer to the workflow spec for further details about seeking fulfillment.