If a trading partner submits a file that has multiple ISAs, and the 1st ISA passes, but the 2nd and 3rd ISA have invalid receiver IDs (longer than 15 characters) causing parser problems, should the 999 that is generated provide a status for each of the ISAs in the file? Or is it standard practice that if the trading partner does not receive an ack for the 2nd and 3rd, they should assume there is a problem and resubmit the file?
A single physical file may contain more than one interchange. Each interchange and its contents are considered separately in all X12 acknowledgments. ASC X12 acknowledgments make no reference to physical files.
With regard to your first question: No, the 999 that is generated *cannot* provide a status for each of the interchanges (starting with the ISA segment) in the file. A 999 Implementation Acknowledgment can only report on a single functional group within an interchange. If indicated by the value of ISA14, Interchange Acknowledgment Requested, the second and third interchanges with the invalid receiver IDs may be reported on by TA1 Interchange Acknowledgments. If ISA14 in a rejected interchange has a value of "0" (zero) the receiver cannot report on that error electronically and must use other methods.
With regard to your second question, when an interchange is sent and an acknowledgment is expected but not received, you should assume there is a problem. Problem resolution varies from trading partner to trading partner.