.\"***************************************************************************
-.\" Copyright (c) 2017 Free Software Foundation, Inc. *
+.\" Copyright (c) 2017,2018 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: user_caps.5,v 1.4 2017/11/25 20:13:12 tom Exp $
+.\" $Id: user_caps.5,v 1.9 2018/07/28 22:05:23 tom Exp $
.TH user_caps 5
.ie \n(.g .ds `` \(lq
.el .ds `` ``
.de NE
.fi
.ft R
-.in -4
+.ie n .in -4
+.el .in -2
..
.de bP
.ie n .IP \(bu 4
.PP
The ncurses utilities \fBtic\fP and \fBinfocmp\fP have a command-line
option \*(``\-x\*('' to control whether the nonstandard capabilities
-are stored or retrieved. A library function \fBuse_extended_names\fP
+are stored or retrieved.
+A library function \fBuse_extended_names\fP
is provided for the same purpose.
.PP
When compiling a terminal database, if \*(``\-x\*('' is set,
.TP 3
AX
\fIboolean\fP, asserts that the terminal interprets SGR 39 and SGR 49
-by resetting the foreground and background color, respectively, to the default.
+by resetting the foreground and background color, respectively, to the default.
.IP
This is a feature recognized by the \fBscreen\fP program as well.
.TP 3
RGB
\fIboolean\fP, \fInumber\fP \fBor\fP \fIstring\fP,
to assert that the
-\fBset_a_foreground\fP and
+\fBset_a_foreground\fP and
\fBset_a_background\fP capabilities correspond to \fIdirect colors\fP,
-using an RGB (red/green/blue) convention.
+using an RGB (red/green/blue) convention.
This capability allows the \fBcolor_content\fP function to
return appropriate values without requiring the application
to initialize colors using \fBinit_color\fP.
explicitly list the number of bits used for red, green and blue components
as a slash-separated list of decimal integers.
.RE
+.IP
+Because there are several RGB encodings in use,
+applications which make assumptions about the number of bits per color
+are unlikely to work reliably.
+As a trivial case, for example, one could define \fBRGB#1\fP
+to represent the standard eight ANSI colors, i.e., one bit per color.
.TP 3
U8
-\fIboolean\fP,
+\fInumber\fP,
asserts that ncurses must use Unicode values for line-drawing characters,
and that it should ignore the alternate character set capabilities
when the locale uses UTF-8 encoding.
kHOM/special form of khome (Home)
kLFT/special form of kcub1 (cursor-left or cursor-back)
kNXT/special form of knext (Next, or Page-Down)
-kPRV/special form of kprev (Prev, or Page-Up)
+kPRV/special form of kprev (Prev, or Page-Up)
kRIT/special form of kcuf1 (cursor-right, or cursor-forward)
kUP/special form of kcuu1 (cursor-up)
.TE