Sometimes things are misunderstood when talking with words. It's best to draw a picture to define exactly where to measure and how.
That's why the auto industry uses blueprints as the "bible" for determining if a part is to specifications or not. It defines clearly the dimensions, taking away the "error of interpretation".
If it is called out on the blueprint, then that specification has to be met. If it is not called out on the blueprint, it can't be held to that spec.
My point is that some people may misinterprit what they are supposed to measure. It may not be their fault as it was not explained clearly to them. That is why it's best to define it as clearly as possible to eliminate "errors in translation/interpretation".