Originally Posted by wgrc1971
That's what I suspected, that they are void. I heard a story that NW monitors the bidding sites and writes down the numbers, and compares them to who purchases the tickets, and then wreaks havoc on their trip (after it is underway, rather than voiding the ticket right away, and they take away FF miles, etc.). That sounds a little like an urban legend though, has anyone heard of this actually happening??
It got to be an urban legend. The e-cert is 1 time use only, and has no name on it. Unless they are really dumb, there is no way the buyer or seller would want to disclose the number/code.
You can find more information from this thread. PD925 discussed there is essentially the same as the PD964 mentioned by Standby4321 except for different expiration date. There are a number of other ones as well PD924, PD886, etc. The thread below tells it all.
http://www.flyertalk.com/forum/showthread.php?t=420383
As of the capacity controll, I don't think so. There were once or twice I couldn't get it work at all; then I realized I couldn't escape from certain Continental operated segments; and the coupon only works on NW/KLM operated flights.