We are requesting guidance on how to respond, if at all, to an Interchange in which validation encounters a fatal error condition, such as a control character, before the "Acknowledgment Requested" indicator in ISA14 can be read; a similar issue is how to respond, if at all, when a fatal error is encountered before the Interchange Control Number in ISA13 can be read.
there is no technical response for the scenarios as described. For these level and types of errors manual intervention is the recommended reponse. You must be able to parse the ISA to create a TA1. If you are unable to parse the ISA, no message can be created. For a formal interpretation, the standards are silent as to what should be done. For further discussion, I would say that in circumstances such as this in which the ISA is so corrupted that a TA1 can not be generated the only alternative is for a person to review the error and take action based on trading partner agreement. This would usually consist of contacting the sender by phone or e-mail, providing as much identifying information about the interchange as can be determined, and requesting they correct and re-send.