I used my AMEX card to access the PER lounge on Friday night. The staff member gave it to a trainee to show how to deal with an AMEX cardholder entry. She told the staff member to click AMEX on the computer and then check the number on the screen and compare to the card, and then check the name and boarding pass, before handing them back to me and welcoming me into the lounge. Yesterday, I used the amex card to access the MEL lounge and also noticed the staff member look at the computer then scrutinize my card. Maybe they have the ability to know what is a supp card now....