At the
www.flyertalk.com website (under the National forum) there are many, many frequent flyers who have successfully used this code without any sort of document request/presentation. They are the "Mavens" of Traveling as we are to Disney Stuff. At that website, you will find lots of other contract codes for National (and other rental companies), many of which are not listed on mousesavers. Flyer Talk is a great site and, if you are interested in getting the most from your money when flying, staying in a hotel or renting a car, it's a fantastic source.
I absolutely adore

Mary's website and can only say good things about it. She is the Queen!

But, it's important to note that she can only post the deals that are reported to her (or those she personally finds). So, while it's a WONDERFUL place to start, it's not an exhaustive list of discounts. I highly doubt that these Flyer Talk folks who travel 250 days of the year and have access to many discounts are emailing Mousesavers with their codes - the majority of them are too work-consumed to take a vacation.