Us senior folks started out with imperial measure, then added metric in the mid 1960's. Then to add to the confusion I was a printer and we had our own measuring system that had no relationship to the afore mentioned.
I use a pica "pole" or line gauge for cutting stripwood because of the T on the end. I also still work in points and picas although I have moved away from columns and gutters from my newspaper days. 12 points to a pica, and 72 points to an inch actually makes for a pretty accurate scale of 1/72". As Herb mentions EM and EN spaces went out the door with computer technology unless your one of us last remaining card carrying Linotype operators in which case a wrong EM or EN space could land a basically hot molten slug in your lap or off your calf as would typing too fast and beating the carriage. Those days did render a strange ability, reading reversed or in the mirror. Thank goodness for the punch tapes and then the CG typesetters. Could you imagine having open hot lead pots in todays world.......I still have about 500 pounds of "pigs" laying around to use as shop weights. I scrapped my linotype about 10 years ago when my mother was the only other one left in my company that could run the monster as we were still producing galleys for the few letter press operators left in the country and our own imprinting uses. I hated changing fonts anyway. OK, OK, off topic rant!