doc/groff.texi: Update trailing space discussion.

* doc/groff.texi (Breaking): Discuss trailing spaces alongside leading
  spaces on text lines here instead of in "Adjustment" node, since the
  semantics of trailing spaces are not altered by adjustment enablement
  or mode.  Add forward reference to "text line" concept.  Move concept
  index entries about leading and trailing spaces here.

  (Adjustment): Remove discussion of trailing spaces.  Clarify concept
  index entry.

1 files changed, 12 insertions, 10 deletions

diff --git a/doc/groff.texi b/doc/groff.texi
index 41c64c766..6afc81f94 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -4778,12 +4778,17 @@ behavior can be modified; see @ref{Blank Line Traps}.  Macro packages
 may discourage or disable the blank line method of paragraphing in favor
 of their own macros.
 
+@cindex leading spaces
+@cindex spaces, leading and trailing
+@cindex trailing spaces on text lines
 @cindex leading space macro (@code{lsm})
 A line that begins with one or more spaces causes a break.  The spaces
 are output at the beginning of the next line without being
 @emph{adjusted} (see below); however, this behavior can be modified
 (@pxref{Leading Space Traps}).  Again, macro packages may provide other
-methods of producing indented paragraphs.
+methods of producing indented paragraphs.  Trailing spaces on text lines
+are ignored.@footnote{``Text lines'' are defined in @ref{Requests and
+Macros}.}
 
 What if there is no next input word?  Or the file ends before enough
 words have been collected to fill an output line?  The end of the file
@@ -4796,17 +4801,13 @@ cause breaks, implicitly or explicitly.  This is discussed in
 @node Adjustment, Tab Stops, Breaking, Text
 @subsection Adjustment
 
-@cindex leading spaces
-@cindex spaces, leading and trailing
-@cindex extra spaces
-@cindex trailing spaces
+@cindex extra spaces between words
 After GNU @code{troff} performs an automatic line break, it then tries
 to @dfn{adjust} the line: inter-word spaces are widened until the text
-reaches the right margin.  Extra spaces between words are preserved, but
-trailing spaces on an input line are ignored.  Leading spaces are
-handled as noted above.  Text can be adjusted to the left or right
-margins only (instead of both), or centered; see @ref{Manipulating
-Filling and Adjustment}.
+reaches the right margin.  Extra spaces between words are preserved.
+Leading and trailing spaces are handled as noted above.  Text can be
+adjusted to the left or right margins only (instead of both), or
+centered; see @ref{Manipulating Filling and Adjustment}.
 
 @c ---------------------------------------------------------------------
 
@@ -11153,6 +11154,7 @@ defined as empty, and a warning of type @samp{mac} is emitted
 If @code{ds} is called with only one argument, @var{name} is defined as
 an empty string.
 
+@cindex trailing spaces in string definitions and appendments
 @cindex comments, with @code{ds}
 @cindex @code{ds} request, and comments
 @strong{Caution:} Unlike other requests, the second argument to the