Diver0001:
I left the calculations visible. Just hide them/set print area as desired to print the table.
M0 is the maximum allowable dissolved N2 pressure at sea level or "surfacing M-value". See that classic article "Understanding M-Values" by Erik Baker. Each of the many entries in the PADI RDP table and my excel spreadsheet are the "NDL" time, but rather than for the full M-value of the 60 minute compartment, its the "NDL" for the reduced M-value associated with each Pressure Group. Erik Baker's article also has the metric M0 info, so you can convert the table to the metric form without too much work.
When reverse engineering the PADI RDP, I found that they chose to make the pressure groups to be integer % of M value. Steps of 3% of the 60 min compartment M-value for most pressure groups, with the A and B pressure groups being bigger jumps. This makes the boundaries of the pressure groups strange looking in FSW of N2. OTOH, the Navy Workmann tables have pressure groups that are nice even increments of fsw (2 fsw/PG IIRC).
One set of calculations not that aren't shown are the NDL calcs for depths deeper than 40'. For those, you just use that same formula that is repeated throughout the table, but using the shorter haltime time constant and the full value of the associated M0 for that compartment. One compartment will have the shortest result. That's the NDL for that depth.
The attached file has the whole table for both 60 min and 30 min compartments, with some added formula for offgassing calculations -- if you look in the 70' row, you can see how the 30 min compartment gets to 98-100% of its limit in 38-40 minutes. That's why the PADI RDP has 40 minute NDL for 70'.
The other calculation I didn't show is the offgassing or SI calcs. If you look at the 0' depth row on the 60 minute table, that is where the SI numbers come from. For the purpose I built that spreadsheet, I wanted to count down from 110% of M-values. The PADI SI table counts down from 98% of 60 min HT M0, if you change row 6 so it starts from 98% then the times are pretty close to PADI RDP table 2 (Or just subtract from the existing spreadsheet values, the 10 minutes that is in the 98%/0' entry already).
As you probably have already figured out, if you change the 0.21 entry to something else, like 0.32, the table will be recalculated for EAN. The NDL are NOT automatically recalculated, just the main body of "time to pressure group" numbers.
