I got a file generated from a CMM machine for measuring some par maters of drilled holes such as circularity and hole size, I also found that it measured perpendicularity (it shows PERP) so I assumed it is perpendicularity. my question is what is the unit usually used for measuring hole perpendicularity. is it mm or degrees. I am just not sure which one is used for drilled holes. also is there a book or a video where it shows how perpendicularity is measured using a CMM machine.