The issue not whether PMK shoulders. I know that it does, and have previosly described shouldering as am important characterisctic of PMK.That has nothing to do with my question.

The issue is what you wrote in an earlier messasge, to wit.

"Pyro and Catechol affect the shoulder of the slope. The tanning clamps the highlights by not letting fresh developer in after a certain amount of development has taken place. Metol based developers will cause less curve at the shoulder because they will permit more blocking in the highlights. It can almost seem like the highlights go out of focus due to the blocking."

You appear to be saying that both pyrogallol and pyrocatechol afftec the shoulder of the slope in a way that is unique to these developers. I am not aware of any research with a similar finiding. If this research has been published somewhere please provide bibliographic information as to the source.