[PATCH 059/100] man/ncurses.3x: Recast "ENVIRONMENT" section, NCURSES_NO_UTF8_ACS (15/21).

[G. Branden Robinson]

Describe the feature so that I can understand it.  To me, the name of
the environment variable name by itself implies nearly the opposite
purpose.
---
 man/ncurses.3x | 66 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 24 deletions(-)

diff --git a/man/ncurses.3x b/man/ncurses.3x
index fa84b5198..e39ba2cd9 100644
--- a/man/ncurses.3x
+++ b/man/ncurses.3x
@@ -1363,27 +1363,44 @@ .SS "\fINCURSES_NO_SETBUF\fP"
 .I curses
 calls such as \fB\%printw\fP(3X) do not.
 .SS "\fINCURSES_NO_UTF8_ACS\fP"
-During initialization, the \fI\%ncurses\fP library
-checks for special cases where VT100 line-drawing (and the corresponding
-alternate character set capabilities) described in the terminfo are known
-to be missing.
-Specifically, when running in a UTF\-8 locale,
-the Linux console emulator and the GNU screen program ignore these.
-\fI\%ncurses checks the \fITERM\fP environment variable for these.
-For other special cases, you should set this environment variable.
-Doing this tells \fI\%ncurses\fP to use Unicode values which correspond
-to the VT100 line-drawing glyphs.
-That works for the special cases cited,
-and is likely to work for terminal emulators.
-.PP
-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\*(''.
-.PP
-As an alternative to the environment variable,
-\fI\%ncurses\fP checks for an extended terminfo capability \fBU8\fP.
-This is a numeric capability which can be compiled using \fB@TIC@\ \-x\fP.
-For example
+At initialization,
+.I \%ncurses
+inspects the
+.I TERM
+environment variable for special cases where VT100 forms-drawing
+characters
+(and the corresponding alternate character set
+.I \%term\%info
+capabilities)
+are known to be unsupported by terminal types that otherwise claim VT100
+compatibility.
+Specifically,
+when running in a UTF-8 locale,
+the Linux virtual console device and the GNU \fI\%screen\fP(1)
+program ignore them.
+Set this variable to a nonzero value to instruct
+.I \%ncurses
+that the terminal's ACS support is broken;
+the library then outputs Unicode code points that correspond to the
+forms-drawing
+characters.
+Set it to zero
+(or a non-integer)
+to disable the special check for terminal type names matching
+\*(``linux\*('' or \*(``screen\*('',
+directing
+.I \%ncurses
+to assume that the ACS feature works if the terminal type description
+advertises it.
+.PP
+As an alternative to use of this variable,
+.I \%ncurses
+checks for an extended
+.I \%term\%info
+numeric capability \fBU8\fP
+that can be compiled using
+.RB \*(`` "@TIC@ \-x" \*(''.
+Examples follow.
 .PP
 .RS 3
 .EX
@@ -1398,9 +1415,10 @@ .SS "\fINCURSES_NO_UTF8_ACS\fP"
 .EE
 .RE
 .PP
-The name \*(``U8\*('' is chosen to be two characters,
-to permit it to be used by applications that use \fI\%ncurses\fP'
-termcap interface.
+The two-character name \*(``U8\*('' was chosen to permit its use via
+.IR \%ncurses 's
+.I termcap
+interface.
 .SS "\fINCURSES_TRACE\fP"
 During initialization, the \fI\%ncurses\fP debugging library
 checks the \fI\%NCURSES_TRACE\fP environment variable.
-- 
2.30.2

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