Most software only understands ASCII characters.
These are the characters from 32 (space) to 126 (tilde). Newlines
might also be supported. If you try to use characters outside of this set, e.g. quotes with directionality, accented a, and so on, then a lot of software won't understand it.
There are several standards for exchanging non-ascii characters, like UTF8, wide characters, html-style escape sequences, and various 256 character extended ascii page schemes. You can't guarantee which of these any given program will support.