Is there some way to preserve the same character I used in programs when the code page is changed in Windows?

For example I have used in some program CHR(198) which is "¯" character in English (code page 1250), but when I change code page to Slovenian (code page 1252) the CHR(198) is "Ã" character.

How to handle this problem?
I need some unique (never (or almost never) used in typing) character to work with, independet of different code pages.