Don Ward

> It's not you.  I didn't understand the question.

It's at least partly me.  Means I didn't state the question well enough.

> No, I don't keep the computer in Nitrox mode at 21% when diving air.

I do for a couple of reasons.  First, seeing what air diving, something I
don't do much of anymore, does to oxygen limits is interesting.  It gives me
something to think about which, in turn, leads to learning.  The other
reason is that I often don't have a choice.  Most of my diving is on nitrox.
I'm one of those low consumption people who can make the most of the extra
time (at the same depth) you get from nitrox.  About the only times I don't
use nitrox is when I'm doing a lot of dives over a short period of time.  I
sometimes run into oxygen, rather than nitrogen limits.  My computers, once
used for nitrox, won't reset for plain air until I'm both O2 and N2 clear.

Lee