Rework the documentation of Spaces, using the Ossanna/Kernighan/Ritter

Heirloom Nroff/Troff User's Manual at the authoritative reference.
Part of our text was outright wrong.

Also, refrain from advertising the paddable non-breaking space `\~'
in the DESCRIPTION, for three reasons:  For nroff mode, -Tascii, and
fixed width fonts in general, it makes no difference, so keep the
discussion simple.  Compared to `\ ', '\~' is of questionable portability.
And if you want to keep words together, it is also more usual that you
don't want padding to intervene either.

Finally, drop the `\c' escape sequence (interrupt text processing)
which is not a special character but an input processing instruction
akin to the \<newline> escape sequence.

1 files changed, 20 insertions, 20 deletions

diff --git a/mandoc_char.7 b/mandoc_char.7
index f6c6e79e..be55f99c 100644
--- a/mandoc_char.7
+++ b/mandoc_char.7
@@ -98,26 +98,27 @@ in literal context, and when none of the following special cases apply,
 just use the normal space character
 .Pq Sq \  .
 .Pp
-When filling text, lines may be broken between words, i.e. at space
+When filling text, output lines may be broken between words, i.e. at space
 characters.
 To prevent a line break between two particular words,
-use the non-breaking space escape sequence
-.Pq Sq \e~
+use the unpaddable non-breaking space escape sequence
+.Pq Sq \e\ \&
 instead of the normal space character.
 For example, the input string
-.Dq number\e~1
+.Dq number\e\ 1
 will be kept together as
-.Dq number\~1
+.Dq number\ 1
 on the same output line.
 .Pp
 On request and macro lines, the normal space character serves as an
 argument delimiter.
-To include whitespace into arguments, quoting is usually the best choice.
-In some cases, using either the non-breaking
-.Pq Sq \e~
-or the breaking
+To include whitespace into arguments, quoting is usually the best choice;
+see the MACRO SYNTAX section in
+.Xr roff 7 .
+In some cases, using the non-breaking space escape sequence
 .Pq Sq \e\ \&
-space escape sequence may be preferable.
+may be preferable.
+.Pp
 To escape macro names and to protect whitespace at the end
 of input lines, the zero-width space
 .Pq Sq \e&
@@ -194,14 +195,13 @@ manual.
 Spacing:
 .Bl -column "Input" "Description" -offset indent -compact
 .It Em Input Ta Em Description
-.It \e~      Ta non-breaking, non-collapsing space
-.It \e       Ta breaking, non-collapsing n-width space
-.It \e^      Ta zero-width space
-.It \e%      Ta zero-width space
+.It Sq \e\ \& Ta unpaddable non-breaking space
+.It \e~      Ta paddable non-breaking space
+.It \e0      Ta unpaddable, breaking digit-width space
+.It \e|      Ta one-sixth \e(em narrow space, zero width in nroff mode
+.It \e^      Ta one-twelfth \e(em half-narrow space, zero width in nroff
 .It \e&      Ta zero-width space
-.It \e|      Ta zero-width space
-.It \e0      Ta breaking, non-collapsing digit-width space
-.It \ec      Ta removes any trailing space (if applicable)
+.It \e%      Ta zero-width space allowing hyphenation
 .El
 .Pp
 Lines:
@@ -661,7 +661,7 @@ The escape sequences
 .Pp
 are interpreted as Unicode codepoints.
 The codepoint must be in the range above U+0080 and less than U+10FFFF.
-For compatibility, the hexadecimal digits 
+For compatibility, the hexadecimal digits
 .Sq A
 to
 .Sq F
@@ -735,9 +735,9 @@ The
 manual page was written by
 .An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .
 .Sh CAVEATS
-The
+The predefined string
 .Sq \e*(Ba
-escape mimics the behaviour of the
+mimics the behaviour of the
 .Sq \&|
 character in
 .Xr mdoc 7 ;