str s="辛匝_ W_č doc";;UTF8
s.unicode ;;to UTF16
s.ansi(s CP_ACP);;to ANSI, using your system ANSI code page. This probably will replace foreign unicode characters to ?.
s.unicode(s CP_ACP)
s.ansi ;;to UTF8 out s ;now ReplaceInvalidFilenameCharacters will replace ? to _