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I've just received a letter from Chase saying that my card has been upgraded to no longer have a credit limit, but a "credit access line" (which they can continue to "refer to credit access line [sic] as credit line or credit limit").
Several articles online mention this as a sneaky trap, but what exactly is the problem for someone who checks their spending regularly? Are charges over some limit incurring a higher interest? The only "danger" I've seen is that the card member might be spending more than if they had hit the limit, but I never hit the limit anyway.