re additional area to consider is when the Sender cannot reach the Recipient (e.g., network down, certificates expired, DNS issues, etc.). These are 400 or 500 http errors and there is existing guidance from the FHIR specification that we will point to in the section as well as providing specific guidance by moving the following note to balloters commenters into the guidance. " 200,202,204+/- OperationOutcome all ok for successful transactions Issue : what does widely use Java client want? 401,404+/- OperationOutcome no point in retry 429 +/- OperationOutcome retry but slow down traffic 500+ +/- OperationOutcome - server issues may retry a few times "