If you've been to London at all over the past few years, you'll have seen the "Watch out for card clash when using Contactless and Oyster" posters. This is nothing new, nor is it unique to ITSO. I don't suspect that a person taking diner's cards for payment in a restaurant would know which to use if handed several at once! -------------------------- I think one of the biggest flaws of the standard is that the cards contain information about their issuer, allowing tickets to be restricted to certain cards. If I could carry just one ITSO card around, that might convince me to use it for all modes of transport, but the inability to issue some tickets on some cards really puts me off.