Here`s a little more information...[/ATTACH]
Now that I'm back from my latest trip I looked again at the drawing you attached and it's worthwhile pointing out it is
not metric. It's French metric. What we've known as metric for the past 50 years is an ISO standard introduced c1965. Prior to that the Japanese, Germans, French, and others had their own variations on metric, many of which corresponded to the later ISO version, but some of which did not. As a case in point, the 2mm x 0.45 that Smiths used in this Chronometric drawing is not an ISO metric standard, but it is a pre-'65 French metric standard (the ISO standard pitch for 2 mm is 0.40 mm).