In the Services Review Response when additional information is being requested, there are two possible attachment control numbers. When the additional information is identified using the PWK segment, the control number is populated in PWK06. When the additional information is identified using a LOINC code, the PWK segment isn't used. In both cases, the Administrative Reference Number in the REF segment is required when HCR01 equals A4 (Pended) and a reference number has been assigned. There is also a possible trace number for the event or each detail line. When using the LOINC codes to request additional information, what is intended to be returned to the UMO with the additional information? When using the PWK segment, is only the PWK06 returned with the additional information, or is the intent that the REF and/or TRN values also be returned?
The PWK segment is supported at both the HLEV (event) and the HLSS (service) loops. Technically the UMO could assign a PWK06 at both the HLEV (for info related to the event) and/or at each HLSS loop. Although it is not clear in the 005010X217 guide, both the PWK and HI segments can be used together. The notes have been clarified in the next version of the guide for their usage. The Administrative Reference Number in the REF segment is required when HCR01 equals A4 (Pended) and a reference number has been assigned by the UMO.
It is specifically stated in section 1.12.5.2 of the 005010X217, "Even if the trading partners can accommodate the use of the LOINC on the 278 response request for additional information, the UMO cannot require that the original requester respond to this request using LOINC in the follow-up response."
The PWK is always required when requesting additional information. The REF is only used to indicate a number that was assigned by the UMO for that specific event that is housed on their database. It can be used for updates to a previous request. A trace number is not necessarily relevant when it comes in requesting additional info. Technically this is just a way to track event or service level info to/from one entity to the other. A change request has been submitted to remove the section 1.12.5.1 TRN notes from a future guide.