X/Open Curses states that the ACS_ definitions are char constants. For
the wide-character implementation (see curs_add_wch), there are analo-
gous WACS_ definitions which are cchar_t constants.
@@ -205,8 +207,44 @@
acters except by using UTF-8 (see the discussion of NCURSES_NO_UTF8_ACS
in ncurses(3x)).
- The TABSIZE variable is implemented in some versions of curses, but is
- not part of X/Open curses.
+
+
+ X/Open Curses assumes that the parameter passed to waddch contains a
+ single character. As discussed in curs_attr(3x), that character may
+ have been more than eight bits in an SVr3 or SVr4 implementation, but
+ in the X/Open Curses model, the details are not given. The important
+ distinction between SVr4 curses and X/Open Curses is that the non-char-
+ acter information (attributes and color) was separated from the charac-
+ ter information which is packed in a chtype to pass to waddch.
+
+ In this implementation, chtype holds eight bits. But ncurses allows
+ multibyte characters to be passed in a succession of calls to waddch.
+ The other implementations do not do this; a call to waddch passes
+ exactly one character which may be rendered as one or more cells on the
+ screen depending on whether it is printable.
+
+ Depending on the locale settings, ncurses will inspect the byte passed
+ in each call to waddch, and check if the latest call will continue a
+ multibyte sequence. When a character is complete, ncurses displays the
+ character and moves to the next position in the screen.
+
+ If the calling application interrupts the succession of bytes in a
+ multibyte character by moving the current location (e.g., using wmove),
+ ncurses discards the partially built character, starting over again.
+
+ For portability to other implementations, do not rely upon this behav-
+ ior:
+
+ o check if a character can be represented as a single byte in the
+ current locale before attempting call waddch, and
+
+ o call wadd_wch for characters which cannot be handled by waddch.
+
+
+
+ The TABSIZE variable is implemented in SVr4 and other versions of
+ curses, but is not part of X/Open curses (see curs_variables(3x) for
+ more details).
If ch is a carriage return, the cursor is moved to the beginning of the
current row of the window. This is true of other implementations, but
@@ -237,7 +275,13 @@