If I had one of these in hand, I would probably filter on NNO first. Not finding it that way, I would themn see if the "part no." or some other identifying number was used - the filters work in such a way that you can only select something if it's been used for that person. Starting the number with "DT" would show that it was actually being used, and I would find my card that way. I don't see a problem with listing these using these numbers.
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 3/4/2024). I have added a large portion of my inventory to the site, and currently have trading turned on (details are in my profile).