X-Git-Url: https://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=man%2Fncurses.3x;h=e69b0d980fdd198c67d58bd338de643547327764;hp=9dcdcd940a4c519afdf348a8916a2aacccb7aea7;hb=d1a026123ac051716cdc16278345c1fb5c843b79;hpb=96d6b16de0d487e5d3aed0302a179dbce11b5d96

diff --git a/man/ncurses.3x b/man/ncurses.3x
index 9dcdcd94..e69b0d98 100644
--- a/man/ncurses.3x
+++ b/man/ncurses.3x
@@ -1,6 +1,6 @@
 '\" t
 .\"***************************************************************************
-.\" Copyright (c) 1998-2009,2010 Free Software Foundation, Inc.              *
+.\" Copyright (c) 1998-2010,2011 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            *
@@ -27,7 +27,7 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: ncurses.3x,v 1.101 2010/12/04 18:38:55 tom Exp $
+.\" $Id: ncurses.3x,v 1.104 2011/05/28 23:19:36 tom Exp $
 .hy 0
 .TH ncurses 3X ""
 .de bP
@@ -734,6 +734,9 @@ Routines that return an integer return \fBERR\fR upon failure and an
 integer value other than \fBERR\fR upon successful completion, unless
 otherwise noted in the routine descriptions.
 .PP
+As a general rule, routines check for null pointers passed as parameters,
+and handle this as an error.
+.PP
 All macros return the value of the \fBw\fR version, except \fBsetscrreg\fR,
 \fBwsetscrreg\fR, \fBgetyx\fR, \fBgetbegyx\fR, and \fBgetmaxyx\fR.
 The return values of \fBsetscrreg\fR, \fBwsetscrreg\fR, \fBgetyx\fR, \fBgetbegyx\fR, and
@@ -930,6 +933,28 @@ and is likely to work for terminal emulators.
 When setting this variable, you should set it to a nonzero value.
 Setting it to zero (or to a nonnumber)
 disables the special check for "linux" and "screen".
+.IP
+As an alternative to the environment variable,
+ncurses checks for an extended terminfo capability \fBU8\fP.
+This is a numeric capability which can be compiled using \fBtic\ \-x\fP.
+For example
+.RS 5
+.sp
+.nf
+# linux console, if patched to provide working
+# VT100 shift-in/shift-out, with corresponding font.
+linux-vt100|linux console with VT100 line-graphics,
+	U8#0, use=linux,
+.sp
+# uxterm with vt100Graphics resource set to false
+xterm-utf8|xterm relying on UTF-8 line-graphics,
+	U8#1, use=xterm,
+.fi
+.RE
+.IP
+The name "U8" is chosen to be two characters,
+to permit it to be used by applications that use ncurses'
+termcap interface.
 .TP 5
 NCURSES_TRACE
 During initialization, the \fBncurses\fR debugging library
@@ -1122,6 +1147,15 @@ A small number of local differences (that is, individual differences between
 the XSI Curses and \fBncurses\fR calls) are described in \fBPORTABILITY\fR
 sections of the library man pages.
 .PP
+Unlike other implementations, this one checks parameters such as pointers
+to WINDOW structures to ensure they are not null.
+The main reason for providing this behavior is to guard against programmer
+error.
+The standard interface does not provide a way for the library
+to tell an application which of several possible errors were detected.
+Relying on this (or some other) extension will adversely affect the
+portability of curses applications.
+.PP
 This implementation also contains several extensions:
 .bP
 The routine \fBhas_key\fR is not part of XPG4, nor is it present in SVr4.