In the 278-13 request, the 2010EB NM103 (patient event transport last name) is situational. In the 278-11 response, the 2010EC (patient event transport last name) is required. If you don't get it in the request, what should go out in the response?R
Your observation is correct there is a descrepancy in the use of 2010 EB/2010EC NM103 in the request and the response the WG will address this in a future guide. You may use a CARC code that has the Health Care Policy message on it without supplying the HCP REF segment if it does not apply to that instance.
Use the word "unknown" in the response.