What is a microinch?
A microinch (µin) is the inch with the SI prefix micro, meaning one millionth, so 1,000,000µin make one inch.
The microinch is mostly seen in surface finish. US drawings give a part's roughness (Ra) in microinches, and a typical machined finish is 63µin, or 1.6µm.
A microinch is a millionth of an inch, which is exactly 0.0254 micrometers or 25.4 nanometers. Outside the US surface finish is given in micrometers instead.
What is a UK nautical league?
A UK nautical league is three UK nautical miles, ie 18,240 feet or 5,559.552 meters, which rounds to 5.56 kilometers. The international nautical league is slightly shorter at 5,556 meters.
Don't confuse it with the land league, which is three statute miles. The nautical league is three nautical miles, about 3.45 statute miles, so it's roughly 15% longer.
Britain's territorial waters once reached one marine league – three nautical miles – from the coast. The limit has been 12 nautical miles, or four leagues, since 1987.