Thanks for the replies!

I don't know why I was given 01A, b/c I was on a NC ticket, although confirmed with miles in advance. Empress, or others, do you have any idea as to why?

SK, I use them to 1) store used tickets for easy access in case something comes up 2) store used BPs, ditto reason 3) sort out bills (various). All I do is stick one of those Post it page markers to label them, and I have easy access to everything!