Why not?
All training agencies specify EANx cylinders must be marked with the classic green and yellow bands.
They do? I took my nitrox class w/ SDI and my Advanced Deco Procedures with NAUI and neither organization specified this.
What reasoning is there not to clearly identify/mark whats in a cylinder?
MY LDS has a couple of cylinders on display that failed their annuals due to corrosion caused from moisture buildup under these completely unecessary tank wraps. The V.I.P. sticker received from an annual inspection will indicate whether or not a tank is nitrox compatible and of course, you should analyze your tank yourself and clearly mark the mix on the tank afer every fill. The wraps are just another way for unscrupulous shops to take your money for a completely unecessary item. I have heard of shops that will only fill tanks with a nitrox wrap that they will be more than happy to sell you, although I have never encountered one.