Comment 18 for bug 1563744

@Jeff,

I am thinking you are wrong.

The purpose of the solder mask clearance is to avoid issues due to registration defects between the copper layer and the solder mask.

If you have set a clearance of 0.008", this is because the registration defect can be up to 0.008" on X axis and Y axis.
And if you want a corner clearance of 0.008", it means you cannot accept a registration error in X+Y axis bigger than 0.0057".

The mask clearance is a XY margin, not a minimal distance between copper and solder mask.

Clearance between copper items is an other thing: it is a minimal distance, not a registration margin.