Local Promotional Rate. I have used these before. At the LAS JW for $149/night.

If the rate rules do not detail any qualifications/requirements then feel free to use it.

FWIW, it looks like a mistake fare. If it is a mistake fare, your guess is as good as anybody else's as to whether they will honor it or not. If you want to know the answer to that quesiton, then contact Marriott Customer Service or the specific hotel... or book it and take your chances.