[EricH]

Originally Posted by SoftwareBug2.0

Do people actually screw this up? There is something to be said for making documentation accessible but please assume that high school students have mastered the ruler.

All. The. Time. It's really awkward when you forget to account for the thickness of a structural member in design and have to account for it in hardware with a sawzall. Been there, done that. Ever since, when working that sort of project, it's been "Did I account for ALL of the intermediate stuff when making this length?"

The other factor, of course, is that it's quite possible to mess up numbers with the mechanical drawings. (Trust me--even with a good drawing, sometimes the only thing saving your bacon is some really good measuring to interpret the drawing.) By saying that X needs Y distance of clearance, they are taking an aspect of the drawings that may or may not be clear to the average EE/programmer and saying "Pay attention to this. You need to take this into consideration. The drawings are less idiot-resistant than we'd like to be able to make them."