Ok ticketing experts out there, here's a tough one.

I have a hand-written paper RTW DONE4 ticket. I had 19 segments used up on it and 5 NA segments, so in order to try and maximize the mileage flown I stuck in a "duplicate" segment. What I mean is that I had the original itinerary set up like so:

JFK-SJU
SJU-JFK
SJU-JFK <-- my plan was to buy a one-way ticket to SJU and just make it a mileage run.

My paper ticket still has coupons for both SJU-JFK segments. When the electronic itineraries were "ticketed" though, they cancelled the second SJU-JFK segment for whatever reason. I decided that I didn't want to make a stink about it and just let it go.

So.... what happens if I show up at the airport in SJU with a paper coupon for this flight (has an actual date and flight number written on the ticket) but there's no record of my reservation in the computer?

As recently as last year, I've shown up at the gate (for a flight from NY to Florida) with merely an open dated coupon (issued by QF). The GA took it, created a reservation, checked me in and gave me my boarding pass in less than two minutes.

Just tell them you're plans changed, the old reservation was cancelled, and that you'd like to use the ticket to travel. It shouldn't be a problem.

However, all this begs the question of how on earth you managed to keep your paper coupons once your ticket was re-issued electronically?!?

My ticket isn't electronic -- it is still a paper ticket. That doesn't change the fact that the reservation is kept in the airline systems in electronic format. The electronic reservation record is the one that doesn't have my "extra" flight.

One of the biggest difficulties people have in this forum is understanding that Reservations and Tickets are two completely separate things. They can be linked if you choose, but it is by no means required. OWE tickets (and many other types) are valid for any flight on any One World airline between the points identified on the ticket coupon which have availability in the relevant class (A/D/L(Y in some specific circumstances)). It is perfectly possibble to have 20 separate and entirely unconnected reservations (generally known as PNRs) in the course of one OWE ticket. There is no need to have reservations corresponding to all the remaining coupons on your ticket - you can make reservations as and when you choose. The only thing to watch is that some airlines may require a ticket number to be entered into the PNR in order to keep it confirmed.