I think at 66 I've a pretty good idea
Ok with the upmost respect, please do not play the age card as if to dismiss the younger generation.
The flap markings are lines with the numbers 5, 15, 20 and 35. These correspond exactly to the degree of flaps deployed.
I can inform you fully that they do not. This is what they're there for and I confirmed this last night and my previous understanding of the numbers was correct;
There are numbers 1 to 5 on the back of the spoilers and are used for replacing those individual panels - There are numbers 2, 3 and 4 written on the flaps themselves and are used for ''flap track'' replacement. There are numbers 1 to 5 written on the slats also used for their individual replacement. Then the numbers begin to go up to 70 and those numbers above 5 are much smaller, they are however used to determine further panel replacement and even down to the finest detail of pipe replacement for hydraulic fluid.
So can I remind you
for the third time,
they are not used to determine flaps stage.