The funny thing about steel, Mr Z, is the way it changes over the years, yet remains the same! When I was a shipwright, a sheet of steel was measured in imperial measure. However, when I was first called up into the RAF for National Service, as a Sheet Metal worker, I found that a sheet of steel was measured in Standard Wire Gauge (SWG). Many years later when managing a Steel Fabrications Factory steel was measured in metric.Consequently, a sheet of steel, one-eighth of an inch thick, became 10 SMG and then 3mm.More useless knowledge ... enough to drive you off the rails
Steel yourself, John.Steel yourself.