ADT - Actual Dive Time, or the total time spent underwater during a
dive. This number is in minutes.
RNT - Residual Nitrogen Time, or the amount measured in minutes
of Nitrogen still in a diver's body after a dive.
TNT - Total Nitrogen Time, calculated by adding ADT and RNT. This
number is used when getting the End-of-Dive group letter from Table 1 for
repetitive dives.
SIT - Surface Interval Time, or the amount of time spent above
water after a dive. Table 2 of the NAUI dive tables uses the SIT to
calculate a new dive group, because Nitrogen is "offgassed" during this
time. Enter this in minutes into DiveCalc - e.g. 2 hours, 35 minutes =
155 minutes.
(A)MDT - (Adjusted) Maximum Dive Time. This is the maximum amount
of time that a diver can spend at the given depth. The word "Adjusted" is
in parenthesis because the Maximum Dive Time is adjusted for repetitive
dives to account for Residual Nitrogen in the body (see RNT). This is done
on Table 3 of the NAUI Dive Tables.