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</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- ESCDELAY and TABSIZE are extensions, not provided in most other imple-
- mentations of curses.
+ <STRONG>TABSIZE</STRONG> is a feature of SVr4 curses which is not documented by X/Open
+ curses.
- ESCDELAY is an extension in AIX curses:
+ <STRONG>o</STRONG> In SVr4 curses, <STRONG>TABSIZE</STRONG> is initially set from the terminal descrip-
+ tion's <STRONG>init_tabs</STRONG> capability. After that, it can be altered by the
+ applications using SVr4 curses.
- <STRONG>o</STRONG> In AIX, the units for ESCDELAY are <EM>fifths</EM> of a millisecond.
+ SVr4 curses uses the current value of <STRONG>TABSIZE</STRONG> to compute the posi-
+ tion of tabstops for updating both the virtual screen with <STRONG>add-</STRONG>
+ <STRONG><A HREF="addch.3x.html">ch(3x)</A></STRONG> as well as the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
- <STRONG>o</STRONG> The default value for AIX's ESCDELAY is 0.1 seconds.
+ <STRONG>o</STRONG> This implementation uses the current value of <STRONG>TABSIZE</STRONG> only for up-
+ dating the virtual screen. It uses the terminal description's <STRONG>it</STRONG>
+ (<STRONG>init_tabs</STRONG>) capability for computing hardware tabs (i.e., tab stops
+ on the physical screen).
- <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for ESCDELAY; this im-
+ <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD curses allows
+ <STRONG>TABSIZE</STRONG> to be set through an environment variable. This implemen-
+ tation does not.
+
+ NetBSD curses does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
+ capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
+ screen.
+
+ <STRONG>ESCDELAY</STRONG> is an extension in AIX curses:
+
+ <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of a millisecond.
+
+ <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> is 0.1 seconds.
+
+ <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; this im-
plementation currently has no upper limit.
- This implementation has long used ESCDELAY with units of milliseconds,
- making it impossible to be completely compatible with AIX. Likewise,
- most users have either decided to override the value, or rely upon its
+ This implementation has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds,
+ making it impossible to be completely compatible with AIX. Likewise,
+ most users have either decided to override the value, or rely upon its
default value.