Yes, but those who use the inch were never limited to 1/1000" My long deceased ex father-in-law worked for De Havilland and then Rolls Royce in the aircraft industry, and I know for a fact they broke the thou down into far smaller increments, and I am sure on very accurate drawings also, don't forget Rolls Royce built the engines for Concorde, surely the Vincent of the skies, it might well be regarded as an outdated measurement today, but I would not denigrate it, some very fine work was produced using the thou.