We would like to update you that starting from next year - 01/01/2020 we will start reusing PNR refs on airline systems.
The system will make sure that no duplicated PNR refs are created for the same calendar year, meaning that in no case, an airline will have the same PNR ref for 2 PNRs created in the same year.
Notice that the "PNR" command on the search bar will now return only the most recent PNR with the ref searched, for receiving all PNRs with that same ref, please use the new command "PNRALL".
For additional information, please use the "?" command on the search bar.