How to Make a Long Vowel Symbol?

[ka jowct]

That mark (the macron) actually exists, and would be very useful to people who teach Latin or need to indicate pronunciation, but for no reason that I can fathom, it isn't a dead key, so you can't get it to land over a vowel, which is the only place you'd want it. I actually modifed a couple of type faces years ago, replacing the circumflex with the macron. This was strictly for Latin text, where the circumflex would not be needed.

It's the shift-option-comma key.¯¯¯¯¯¯¯¯ Its short vowel friend is right next door on the period key.