Thanks -- I guess I was the one that provided the "challenge", but I hope it did not come across as confrontational.

What those numbers mean is that if you were to do a cut that was 1608mm long, you'd be out of square by 0.3mm, which by all measures should be acceptable.

Your value of 0.0002 is in radians. This can easily be converted to 0.2millirad. To convert to degrees (for angles this small) you multiply by 180/pi which comes out to 0.011 deg, or 0.69 minutes of arc (arc minutes), or 41 seconds of arc (arc seconds).