Eh, if someone tells me to reduce a tolerance from 5 to 10 thou at work, it’s understood that it’s +/-5 and 10. I don’t think I’ve ever heard someone use the full range of a tolerance in conversation. If the tolerance isn’t bilateral, it would be said like plus 5, minus zero. Anyways, +/- .0005" is our standard tolerance on the span of all dowel hole pairs.