Please be nice, but I need a good explanation about upgrading in general, specifically BF. I am fairly new to CO and do not quite understand how it works even after reading the information on continental.com. I understand (mostly) how the EUA system works and makes sense. If there are EUA's then what is the point of the mileage upgrades- is it mostly for non-elites that want to sit in F or what? And if you use miles for an upgrade, are you guaranteed the upgrade or not? Now, for BF, when you are looking at the flight information on continental.com or the PDA site and it shows a BF flight with the upgrade list, how are those people on that list? Do they request these upgrades with miles or is it like domestic travel where you book as an elite (say plat.) and you will clear an upgrade 5/3/1 day(s) in advance? Please provide as much information as possible and thanks ahead of time for all of your responses; the understanding and explanations are of great help!