ISO[2]-Coding Position 1-2 / A-Z

[hummg]

At the moment, we are again discussing the ISO code assignment of the seating position on a bus or very large van.
I found an older but already closed post in the forum. (Suggestions/Additional codes/ Not enough seating locations in ISO MME)
viewtopic.php?p=714&hilit=position#p714

Unfortunately, I only found a very general hint in the RED_A.
For this reason I want to ask if there are any new findings?

KR Guido