Blackwood
Contributor
and totally irrelevant to the topic.
You jumped past my edit.
"(or if you mark them at all) ... As a team, decide what you are going to do. If it makes sense to mark them a certain way such that the team knows what everyone is breathing and understands the functional limiting parameters of the dive, do so."
the point is MARK THEM.
Agreed. I believe that marking all bottles is rock solid and appropriate. I could be convinced to rotate the "6" on my 21/35 bottle around (i.e. MOD of 1.4 instead of 1.2), but will not mark it 220 as suggested by Dsix36. No one with whom I dive treats 1.6 as anything but shallow deco. If they're using my bottle without knowing what's in it, that's on them, and it's up to them whether or not to proceed that extra 30 feet.