The XL/XE has another set of letters and numbers the international, or European, character set. You can switch from your normal ATASCII display to this set by POKE 756,204 ($2F4) and return to the American set by POKE 756,224. If you change over, try typing several CONTROL-key combinations to see the other character set.
The international character set takes 1K of memory from 52224 to 53247 ($CC00-$CFFF). If you use a program to turn your OS ROM into OS RAM, you can use this space for your own routines or graphics.