[anjbe]

In the old days of ASCII several characters were heavily overloaded. On teletypes it was not unusual to create accented characters by typing ` or ' (which looked more like ´), then backspacing and typing a vowel, to get (e.g.) è or é. The same could be done with ~ to create ñ, if the tilde were high up like ˜, or with " to simulate an umlaut.

And of course there’s the overload of hyphen and minus, such that Unicode gave up and named U+002D “hyphen‐minus,” and created two separate characters U+2212 “minus” (−) and U+2010 “hyphen” (‐) to use in situations where the typography matters. Most fonts seem to use identical glyphs for hyphen‐minus and minus, but I’ve seen some that try to split the difference, giving hyphen‐minus a glyph with a height and width somewhere in between hyphen and minus.

If you find minus and hyphen‐minus hard to distinguish visually, just remember that a true minus sign looks just like a plus without the vertical part. Compare the alignments:

- example (U+002D hyphen‐minus)

+ example (plus)

− example (U+2212 minus)

[drfuchs]

And typewriters, before that. They all had only a single key for Apostrophe as well as Single Left Quote and Single Right Quote. In fact, since most(?) manual typewriters also lacked a "One / Exclamation" key, there was a fourth use: for "1" you typed lower-case L (yikes); while to get an exclamation point, you had to type a period, then backspace, then overstrike with an apostrophe (which is yet another reason the apostrophe et. al. character was vertical!)