I notice that the marking template for every progressive listed in the identifier has 15 mm from the fitting cross to the top of the near power circle, 20 mm to the bottom of the circle, about 18 to the middle, including short-corridor progressives.

Is this similarity significant? Aren't the diagrams provided by each manufacturer, or does the publication set the criteria for where to read the near power and distance power?

I would assume that the position of the near power circle would vary, since corridor length, whatever the definition, would vary from lens to lens.

Any insight on this? I posted this on the general discussion forum, but got no help. Your input is appreciated.