[docs]: Reduce use of term "entity".

Doug McIlroy noted this vague term, which groff employs for multiple
purposes.  Eliminate its application to input processing.  There is now
no longer such a thing as an "entity" in the groff language.

* doc/groff.texi (Character Translations): Do it.  Also clarify
  "nothing" as "the dummy character".

  (Using Symbols): Do it.  Also recast explanation of difference between
  characters and glyphs.  Explicitly state that spaces aren't glyphs.
  Document that `rchar` request can't remove definitions supplied by
  font description files.

  (Ligatures and Kerning): Speak of "special characters", not
  "entities".

  (Other Differences): Recast discussion of character-to-glyph
  transformation.  Stop qualifying characters as "input".  Recast
  discussion of example.

* font/devutf8/NOTES: Revise use of terminology.  Perform a Kemper
  notectomy.  Wrap long lines.

* man/groff.7.man (Request short reference) <char>: Speak of a "special
  character", not an "entity".

  <rchar>: Document that request can't remove definitions supplied by
  font description files.

* man/groff_diff.7.man (Implementation differences): Sync with our
  Texinfo manual.

The use of "entity" to describe how a glyph gets mapped back to a
character (sequence) for the HTML and terminal output devices is
retained.  That usage is restricted to discussion of output drivers
(code comments and function names notwithstanding).

1 files changed, 17 insertions, 17 deletions

diff --git a/font/devutf8/NOTES b/font/devutf8/NOTES
index 0906b8ade..c20edebd4 100644
--- a/font/devutf8/NOTES
+++ b/font/devutf8/NOTES
@@ -1,47 +1,47 @@
-Note that all \[charXXX] entity names have been removed from the font files.
-They don't make sense for Unicode.
+All \[charXXX] special character names have been removed from the font
+files.  They don't make sense for Unicode.
 
-The following entity from the original troff manual (by Ossanna and
-Kernighan) is unmapped:
+The following special character name from the AT&T troff manual by
+Ossanna and Kernighan is unmapped:
 
   bs    shaded solid ball (Bell System logo, AT&T logo)
 
-Character 0x002D has not been given a name because its Unicode name
+Code point 0x002D has not been given a name because its Unicode name
 HYPHEN-MINUS is so ambiguous that it is unusable for serious typographic
-use.
+work.
 
 \[wp] has been mapped to 0x2118, because according to Unicode 4.1's
 NamesList.txt, U+2118 SCRIPT CAPITAL P is really a Weierstrass 'p',
 neither SCRIPT nor CAPITAL.
 
 The following line could be added; \[space] is known to devps but is not
-documented and not known to devdvi (actually, there is no space glyph within
-the TeX system).
+documented and not known to devdvi (actually, there is no space glyph
+within the TeX system).
 
   space   24   0   0x0020
 
-devps maps \[*U] to 'Upsilon1', which is equivalent to 0x03D2.  We map it to
-0x03A5 instead.
+devps maps \[*U] to 'Upsilon1', which is equivalent to 0x03D2.  We map
+it to 0x03A5 instead.
 
-devps maps \[*W] to 'Omega', which is equivalent to either 0x2126 or 0x03A9.
-We map it to 0x03A9.
+devps maps \[*W] to 'Omega', which is equivalent to either 0x2126 or
+0x03A9.  We map it to 0x03A9.
 
-devps maps \[*D] to 'Delta', which is equivalent to either 0x2206 or 0x0394.
-We map it to 0x0394.
+devps maps \[*D] to 'Delta', which is equivalent to either 0x2206 or
+0x0394.  We map it to 0x0394.
 
 
 Adding Unicode characters
 -------------------------
 
 Assume you want to use a Unicode character not provided in the list, say
-U+20AC. You need to do two things:
+U+20AC.  You need to do two things:
 
 - Add a line
 
     u20AC   24   0   0x20AC
 
   (the second column is computed as 24 * wcwidth(0x20AC)) to the file
-  R.proto, or, when groff is already installed, to the four fonts files in
-  $(prefix)/share/groff/<version>/font/devutf8/.
+  R.proto, or, when groff is already installed, to the four font
+  description files in $(prefix)/share/groff/<version>/font/devutf8/.
 
 - In your source file, use the notation \[u20AC] to access it.