paul@tal:~$ od --format=x1z tmp/tonos-oxia
0000000 74 6f 6e 6f 73 3a 20 ce ae 0a 6f 78 69 61 3a 20 >tonos: ...oxia: <
0000020 20 e1 bd b5 0a > ....<
Here are the two Unicode ranges (PDF):
modern Greek: http://unicode.org/charts/PDF/U0370.pdf
ancient Greek: http://unicode.org/charts/PDF/U1F00.pdf
Then again, try explaining to tech people the difference between ή and ἠ and how you can get ἤ or ᾔ. :-)
How do you enter them nowadays by the way? In the early days of the internet before unicode there were special fonts from SIL for example that first of all were using Latin characters (you'd type W and it would look like Ω) and secondly I think had the diacritics as separate characters, so the font would combine them. It was messy but at least you could type it on a normal keyboard. You could even read it in its ASCII form, most of the hacks were pretty reasonable.
Personally I type Greek using a vim keymap file, usually when writing LaTeX. I believe my keymap file is influenced by those older non-Unicode fonts, because I type w for ω and ;h for ή and >~h| for ᾖ. But my fellow students would mostly use Word. I don't know how they would type the letters, but commonly they would mix the tonos letters with everything else. I think what was happening is that Word would automatically substitute fonts that offered those codepoints, so it would end up showing Times for the letters with tonos and Palatino for the others (or something like that). Hence the ransom note effect.
"Programmers use the grave accent symbol as a separate character (i.e., not combined with any letter) for a number of tasks. In this role, it is known as a backquote or backtick."
Manpages aren't written in TeX though (apparently they use something called "roff"), but they also contain things like `read' instead of 'read'... perhaps manpage writers tended to like TeX too?
http://www.read.seas.harvard.edu/~kohler/class/aosref/ritchi...