When mating a fastener with a threaded hole, it is a good idea to specify a projected tolerance zone. Projected tolerance zones address the geometric effects of tilting within the tolerance zone. The value for the projected tolerance zone should be equal to the distance from the mating surface through the maximum thickness of the mating parts. In some cases, the tolerance zone must extend beyond the mating part when more than one part mates with the same fixed fastener or when needed to address assembly issues.