Encoding symbols and characters in digital form is fairly easy—but making sure that everyone in the world is doing it in the same way sure isn't.

UTF-8 does work in the Terminal, but your unix apps may not be able to handle it. Create a UTF-8 file with whatever characters you please, and then "cat". It should show up. "ls", on the other ...

The Unicode standard recognizes code points within PUAs as legitimate Unicode character codes, but does not assign them any (abstract) character.