By default, "Z" always allows entry of any character code from 0 to 255. This includes allowing the entry of keycodes for international characters, graphics characters, and non-printable characters in the extended character set.
In contrast, the picture control characters "A", "X", "*", and "!" allow entry only of characters in the keycode range of 32 through 127; this is the default. This does not allow the user to enter the international characters and symbols that are available in the IBM Extended Character Set and various other character sets available for other terminals and operating systems.
The IBM Extended Character Set extends the normal ASCII character set by including symbols, international letters, Greek letters, line drawing characters, and block graphics characters. The IBM Extended Character Set has keycodes ranging from 0 to 255 and is recognized by the IBM PC and PS/2.
You can enable support for characters in the range of 128 to 255 by including the extended character set header file vv_extch.h.
When vv_extch.h is #included, "A", "X", "*", and "!" will recognize characters in the IBM Extended Character Set. "A" recognizes all the alphabetic characters, "X" recognizes all printable characters except block graphics and line drawing characters, and "*" and "!" correctly convert international characters to lowercase and uppercase, respectively.
