The "Nitrox" band means that at some point, the tank might have contained something other than plain air. Or Not. It's pretty much meaningless, except as a signal to non-nitrox certified divers that they're probably grabbing the wrong tank.
However, since the tank will need to be emptied and inspected and probably cleaned, and may need a hydro test before use, it really doesn't matter if it says "Nitrox", "This End Up" or has smiley faces on it, since the stickers will all be removed anyway.
In any case, taking a poke at the OP's training for not knowing about the various stickers is completely inappropriate. According to his profile, the OP is AOW certified, not Nitrox certified and would have no way of knowing about the various sticker meanings, aside from VIP.
Terry
Harsh? All I did was question his training. Do you all mean to say that during the equipment portion of the class that the instructor does not cover this? It was in my OW class. And it is one of the things I have carried into my classes. I have a tank with a nitrox band on it because I bought it new and it was on there, And the shop that does my vis's puts a new one on every time. But they don't charge me for it. As a result it is always present in my classroom presentation on gear to demonstrate that there are no real differences. Students may see this at some resorts and on some boats and they have air in them. What are they supposed to do? Look foolish when they say I can't use that tank, it has air in it and it's not supposed to? There are several shops that when their supply of non nitrox 80's will run low, they'll start giving out the ones with nitrox bands on them. Should the uninformed student refuse it? I'm really getting tired of being jumped on for trying to open people's eyes to what is right in front of them.