I suspect that advance-purchase rates are excluded for two reasons:

1. They are already quite low, and Marriott is unwilling to discount them more.

2. Using a certificate on an advance-purchase rate imposes certain practical difficulties that Marriott would rather avoid.

In any case, the certificates are certainly clear enough that they don't apply to those listed rates. The only possible confusion regards what rates are publicly available. We have long debated the status of AAA rates, for instance.

Bruce