Also keep in mind that the readout you'll be looking for must be compared to the allowable perp tolerance, which can range from .0007 to .0011. This is because of bonus tolerance, which comes into play whenever the circled M is invoked. (I mention this in case you're not familiar with that concept, because most CMMs account for it automatically.)
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems