* man/groff.man: Mention glyph and characters.

Minor other updates.
* man/groff_char.man: Minor updates.
* man/groff_diff.man: Better clarification between characters and
glyphs.

3 files changed, 53 insertions, 34 deletions

diff --git a/man/groff.man b/man/groff.man
index 66814edb..7f4e0cf0 100644
--- a/man/groff.man
+++ b/man/groff.man
@@ -486,6 +486,23 @@ and
 On text devices, all glyphs have a constant width anyway.
 .
 .P
+.B Glyphs
+are visual representation forms of
+.BR characters .
+In groff, the distinction between those two elements is not always
+obvious (and a full discussion is beyond the scope of this man page).
+.
+A first approximation is that glyphs have a specific size and
+colour and are taken from a specific font; they can't be modified any
+more \[en] characters are the input, and glyphs are the output.
+.
+As soon as an output line has been generated, it no longer contains
+characters but glyphs.
+.
+In this man page, we use either `glyph' or `character', whatever is
+more appropriate.
+.
+.P
 Moreover, there are some advanced roff elements.
 .
 A
@@ -1257,7 +1274,7 @@ unprocessed to stdout or to the diversion.
 .
 .TPx
 .REQ .cflags "mode c1 c2 .\|.\|.\&"
-Treat glyphs
+Treat characters
 .IR c1 ,
 .IR c2 ,
 .I .\|.\|.\&
@@ -1558,7 +1575,7 @@ and pad glyph to\~\c
 .
 .TPx
 .REQ .fchar "c anything"
-Define fallback glyph
+Define fallback character (or glyph)
 .I c
 as string
 .IR anything .
@@ -1598,7 +1615,7 @@ name on position
 .
 .TPx
 .REQ .fschar "f c anything"
-Define fallback glyph
+Define fallback character (or glyph)
 .I c
 for font
 .I f
@@ -2181,7 +2198,7 @@ to marked vertical place (default scaling indicator\~\c
 .
 .TPx
 .REQ .schar "c anything"
-Define global fallback glyph\~\c
+Define global fallback character (or glyph)\~\c
 .I c
 as string
 .IR anything .
diff --git a/man/groff_char.man b/man/groff_char.man
index 09256186..cfddcd7d 100644
--- a/man/groff_char.man
+++ b/man/groff_char.man
@@ -411,7 +411,7 @@ character representations outside of the printable \%7-bit ASCII range.
 .
 .P
 Some of the predefined groff escape sequences (with names of length\ 1)
-also produce single characters; these exist for historical reasons or
+also produce single glyphs; these exist for historical reasons or
 are printable versions of syntactical characters.
 .
 They include `\f(CW\e\e\fP', `\f(CW\e\'\fP', `\f(CW\e`\fP', `\f(CW\e-\fP',
@@ -1258,7 +1258,7 @@ square root sign.
 .2e hbar uni210F u210F
 .
 .Pa
-.I Greek characters
+.I Greek glyphs
 .P
 These glyphs are intended for technical use, not for real Greek; normally,
 the uppercase letters have upright shape, and the lowercase ones are
diff --git a/man/groff_diff.man b/man/groff_diff.man
index 40713e4d..1477f864 100644
--- a/man/groff_diff.man
+++ b/man/groff_diff.man
@@ -98,7 +98,7 @@ The names of number registers, fonts, strings/\:macros/\:diversions,
 special characters (glyphs), and colors can be of any length.
 .
 In escape sequences, additionally to the classical `\fB(\fP\fIxx\fP'
-construction for a two-character name, you can use
+construction for a two-character glyph name, you can use
 `\fB[\fP\fIxxx\fP\fB]\fP' for a name of arbitrary length.
 .
 .TP
@@ -743,7 +743,7 @@ intervening space.
 .B \[rs])
 Like
 .B \[rs]&
-except that it behaves like a glyph declared with the
+except that it behaves like a character declared with the
 .B cflags
 request to be transparent for the purposes of end-of-sentence
 recognition.
@@ -965,7 +965,7 @@ This is the same as
 .
 .TP
 .BI .cflags\  n\ c1\ c2\|.\|.\|.\&
-Glyphs
+Characters
 .IR c1 ,
 .IR c2 ,\|.\|.\|.\&
 have properties determined by
@@ -974,57 +974,59 @@ which is ORed from the following:
 .
 .RS
 .IP 1
-The glyph ends sentences (initially glyphs
+The character ends sentences (initially characters
 .B .?!\&
 have this property).
 .
 .IP 2
-Lines can be broken before the glyph (initially no glyphs have
-this property); a line is not broken at a glyph with this
-property unless the input characters associated with those glyphs
-on each side both have non-zero hyphenation codes.
+Lines can be broken before the character (initially no characters have
+this property); a line is not broken at a character with this property
+unless the characters on each side both have non-zero hyphenation
+codes.
 This can be overridden with value 64.
 .
 .IP 4
-Lines can be broken after the glyph (initially glyphs
+Lines can be broken after the character (initially characters
 .B \-\[rs][hy]\[rs][em]
-have this property); a line is not broken at a glyph with
-this property unless the input characters associated with those
-glyphs on each side both have non-zero hyphenation codes.
+have this property); a line is not broken at a character with this
+property unless the characters on each side both have non-zero
+hyphenation codes.
+
 This can be overridden with value 64.
 .
 .IP 8
-The glyph overlaps horizontally (initially glyphs
+The glyph associated with this character overlaps horizontally
+(initially characters
 .B \[rs][ul]\[rs][rn]\[rs][ru]\[rs][radicalex]\[rs][sqrtex]
 have this property).
 .
 .IP 16
-The glyph overlaps vertically (initially glyph
+The glyph associated with this character overlaps vertically
+(initially glyph
 .B \[rs][br]
 has this property).
 .
 .IP 32
-An end-of-sentence glyph followed by any number of glyphs with
-this property is treated as the end of a sentence if followed by
-a newline or two spaces; in other words the glyph is transparent
-for the purposes of end-of-sentence recognition; this is the same as
-having a zero space factor in \*[tx] (initially glyphs
+An end-of-sentence character followed by any number of characters with
+this property is treated as the end of a sentence if followed by a
+newline or two spaces; in other words the character is transparent for
+the purposes of end-of-sentence recognition; this is the same as having
+a zero space factor in \*[tx] (initially characters
 .B \[dq]')]*\[rs][dg]\[rs][rq]
 have this property).
 .
 .IP 64
 Ignore hyphenation code values of the surrounding characters.
-Use this in combination with values 2 and\~4 (initially no glyphs have
-this property).
+Use this in combination with values 2 and\~4 (initially no characters
+have this property).
 .RE
 .
 .TP
 .BI .char\  c\ string
-[This request's name is a misnomer since it constructs output objects
-(glyphs) not input objects (characters).]
+[This request can both define characters and glyphs.]
 .
 .IP
-Define glyph\~\c
+Define entity\~\c
 .I c
 to be
 .IR string .
@@ -1346,7 +1348,7 @@ request for more information on font families.
 .
 .TP
 .BI .fchar\  c\ string
-Define fallback glyph\~\c
+Define fallback character (or glyph)\~\c
 .I c
 to be
 .IR string .
@@ -1373,7 +1375,7 @@ switch to the previous fill color.
 .
 .TP
 .BI .fschar\  f\ c\ string
-Define fallback glyph\~\c
+Define fallback character (or glyph)\~\c
 .I c
 for font\~\c
 .I f
@@ -1960,7 +1962,7 @@ to
 .
 .TP
 .BI .schar\  c\ string
-Define global fallback glyph\~\c
+Define global fallback character (or glyph)\~\c
 .I c
 to be
 .IR string .
@@ -3115,7 +3117,7 @@ True if there is a color named
 .
 .TP
 .BI .if\ c ch
-True if there is a glyph
+True if there is a character (or glyph)
 .IR ch
 available;
 .I ch