Quote: (Originally Posted by cameron)
...Keep a large marking that indicates the mix close to the neck of the bottle so you can visualy see the mix you are putting in your mouth...
I think it was mentioned on the last paragraph of my post about labelling...
Marking is of course required. However, there could be times when you can't see the marking and force to know which tank containing which gas (i.e. silt-out, light failure, etc).