2015 Sierra 2500HD 6L90 what is "Pattern A" ?

I'm just getting started tuning my 2015 Sierra 2500. I'm trying to make sense of the "Normal" vs "Pattern A" in the shift scheduling and TCC tables. There is also "pattern B" but that is clearly the tow/haul mode. As far as I know, there are no other driving modes (apart from tow/haul) that are selectable in the vehicle so I'm struggling to understand what "pattern A" is and why the shifting and TCC tables are different than "normal". Can anyone shed some light on this?

Edit: after looking at the "trans shift mode" data in the VCM scanner, I can see that Pattern A is Tow/Haul mode. Not sure what Pattern B is. Maybe it doesn't matter.

pattern B is manual mode, its active when you put shifter in M5 or M6

This isn't consistent across platforms.. Some are flat out not used. Some are used for cruise, tow/haul, or performance shift depending on the application.

Some default (like normal drive) in Pattern B even.. (CTSV)

You can log trans shift mode or something along those lines and see what pattern you are using.