From a PCB fabricator's perspective, what is the best way to specify component clearance and mounting holes? Thru-plating is optional, holes can be plated or not, doesn't matter. Obvious choices are 1) a board-layer pad with a thru-hole either the same size, or slightly larger or smaller (which?); 2) a 4-quadrant "arc" (circle) placed on the board layer, which would show the hole outline when the board outline is viewed? My concern is that if top/bottom layers are filled (flooded with copper) in the hole area, the hole might be missed somehow. Thanks!