ncurses 6.1 - patch 20190216

[ncurses.git] / man / curs_variables.3x

diff --git a/man/curs_variables.3x b/man/curs_variables.3x
index 6b9fb59a4db002af602625dddd5f877df678e3e9..fffad7149ecf29c0d251ea244c56869b8f23480a 100644 (file)
--- a/man/curs_variables.3x
+++ b/man/curs_variables.3x
@@ -1,5 +1,5 @@
 .\"***************************************************************************
-.\" Copyright (c) 2010-2017,2018 Free Software Foundation, Inc.              *
+.\" Copyright (c) 2010-2018,2019 Free Software Foundation, Inc.              *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *
@@ -26,7 +26,7 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: curs_variables.3x,v 1.11 2018/07/28 22:37:10 tom Exp $
+.\" $Id: curs_variables.3x,v 1.12 2019/02/16 23:43:23 tom Exp $
 .TH curs_variables 3X ""
 .ie \n(.g .ds `` \(lq
 .el       .ds `` ``
@@ -139,19 +139,38 @@ or \fBnewterm\fR(3X).
 If \fBcurses\fP is configured to use separate curses/terminfo libraries,
 most of these variables reside in the curses library.
 .SH PORTABILITY
-ESCDELAY and TABSIZE are extensions,
-not provided in most other implementations of curses.
+\fBTABSIZE\fP is a feature of SVr4 curses
+which is not documented by X/Open curses.
+.bP
+In SVr4 curses, \fBTABSIZE\fP is initially set from the terminal description's
+\fBinit_tabs\fP capability.
+After that, it can be altered by the applications using SVr4 curses.
+.IP
+SVr4 curses uses the current value of \fBTABSIZE\fP to
+compute the position of tabstops for updating both
+the virtual screen with \fBaddch\fP(3X) as well as
+the physical screen with \fBmvcur\fP(3X).
+.bP
+This implementation uses the current value of \fBTABSIZE\fP only for
+updating the virtual screen.
+It uses the terminal description's \fBinit_tabs\fP capability for
+computing tab stops on the physical screen.
+.bP
+Other implementations differ.
+For instance, NetBSD curses allows \fBTABSIZE\fP to be set through
+an environment variable.
+This implementation does not.
 .PP
-ESCDELAY is an extension in AIX curses:
+\fBESCDELAY\fP is an extension in AIX curses:
 .bP
-In AIX, the units for ESCDELAY are \fIfifths\fP of a millisecond.
+In AIX, the units for \fBESCDELAY\fP are \fIfifths\fP of a millisecond.
 .bP
-The default value for AIX's ESCDELAY is 0.1 seconds.
+The default value for AIX's \fBESCDELAY\fP is 0.1 seconds.
 .bP
-AIX also enforces a limit of 10,000 seconds for ESCDELAY;
+AIX also enforces a limit of 10,000 seconds for \fBESCDELAY\fP;
 this implementation currently has no upper limit.
 .PP
-This implementation has long used ESCDELAY with units of milliseconds,
+This implementation has long used \fBESCDELAY\fP 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.