− — – -
Another type of dash frequently unused is the minus (first in the sequence above), replaced by the hyphen.
An em is a variable unit of measurement based on the point size of the font.
The em dash should be the same width as the height of the font. So, if using 24pt text, the em dash should be 24pt wide. The M might often be near to the width but that is coincidental. An en is half the width of an em (24pt font 12pt en). Again the comparison to an N is coincidental.
Ems and ens aren’t often used as units of measurement any more, but you can find them on old type spec documents.
