ｓ－ｘｐｆの刻印に、ｐとｂがあるが、何を表している？ | オーエスジー

There are P and B on the S-XPF inscription, but what do they represent?

The P and B in the S-XPF engraving represent the length of the chamfer , which is the part to be processed by the rolling tap. P (plug) is 4 pitches long for through hole , and B (bottom) is 2 pitches long for stop holes.