Originally Posted by Donegal

I believe it is correct. When an IATA ticket document is reissued you get a new document (with QR starting 157-...) and if there is nothing charged for this ticket except for the amount already charged in the original document the total fare box say "NO ADC" = No additional collection, because this would be the accounting amount charged to a credit card or paid in cash.
Now - these so called vouchers seem to be Electronic Miscellaneous Document (EMD)s - these are basically pre-paid tickets for services like extra baggage etc or they are unspecified. As opposed to tickets they do not include a routing or flights - they are just a value document that is invalidated when used for the service. QR seems to reissue the rest-value of the ticket into an EMD and these documents follow the same accounting logic as tickets ... ie if nothing is charged on top of the origional document's value they show NO ADC in the total fare box. Bit complicated but I believe everything is in good order with the vouchers.