On schweser book 4 study session 14, page 261, it says "in the case of non-amortizing collateral, due to the call provision on the ABS, while the underlying collateral(loans) has no prepayment risk, the securities backed by such collateral may have prepayment (call) risk.
What does this mean? How can underlying loans not have prepayment risk? (You can always pay off your credit card princpal early, no?) can someone explain this?