I called to request an early checkin, on an upcoming reservation.
Got an email that said: "... Marriott will make every effort to accomodate the below requests, however they are not guaranteed. K1; E1; H1."
Thought that was pretty odd.
This may be a list of such codes, from the web (the three listed on my reservation match). Gives me alot of ideas as to new things to request
http://www.sporcle.com/games/BadMood...-codes/results