John, you've got part of the answer. The local high-speed cable outfit (Shaw) does not use the latest version of Netscape. I have 6 installed, but it will sit there until the cable people learn to count above 5. Of course I can use more than the 255 Iso chars, and they would print if I change to Cyrillic, or whatever. Usually I just want one character, so switching back and forth is not worth it. I occasionally type Spanish words, but the standard Iso chars are fine for that (not like Irish where they seem to use grave or acute marks with damn near every letter- I always thought a fada was a Portuguese wail).
None of this helps me with the macron vowels I would like to use with Netscape. If I used IE, I would have to know that my recipients ALSO are using it. This region, e. g., has millions of people, the computer-users in centers with cable mostly using Shaw and most sticking with Netscape, which is more user-friendly for mail, searching through googles and book-marking.
Telus is in the process of setting up a competing high-speed system, but they ain't there yet. I don't know what they will use.