Originally Posted by
JAXBA
The OP's ghost segment is going to be from RET (I expect meant to be short for RETention, but happens to be the city code for Rost in Norway) to YYY (maybe someone thinking of generic IATA code YY and added an extra Y?). The default preset GK segment entered by Pegasus was for actual JFK flights, like T8191 had, but messages would end up being sent for flights that pax weren't actually booked on, so presumably BA moved to something more generic - RETYYY - that didn't really exist but now raises weird questions. Personally I preferred LONLON as a vanilla dummy segment whenever I had to add one manually.
The Amadeus standard would be just a MIS[C] segment, but BA.com (and Concessions Online) probably aren't be able to display those, so ghost segments are used as well. PNRs stay alive for 3 days past the date of the last segment (of whatever type), so a far flung dummy segment will keep the PNR alive for a long time.
Ahhhhh yes you stumbled upon what i think it is too. The ghost added to voucher bookings appears as a sector that is ZZZYYY. This is added automatically rather than being added manually by an agent. I guess BA.com is reading the YYY part which seems to be the airport code for Mount Joli.