"Em and en refer to units of typographic measurement, not to the letters M and N. (Yes, the homophony is confusing. To disambiguate, loud print shops referred t

"Em and en refer to units of typographic measurement, not to the letters M and N. (Yes, the homophony is confusing. To disambiguate, loud print shops referred to them as mutton and nut.) In a traditional metal font, the em was the vertical distance from the top of a piece of type to the bottom. The en was half the size of the em. Originally, the width of the em and en dashes corresponded to these units." https://practicaltypography.com/hyphens-and-dashes.html https://practicaltypography.com/hyphens-and-dashes.html Handwriting allows one to vary the point (width) of individual letters. Printing presses do not afford that luxury.