doc/meref.me.in: Fix content and style nits.

* Annotate empty default arguments more consistently.
* Prefer active voice.
* Mark footnote overflow as a topic that should get more explanation,
  but is blocked by bugs.
* Generalize commentary on styling/decoration macros; not all have to do
  with font styles.  Refer to what happens at the end of an input line
  as a "word break".  Hard to express that economically: it's a
  potential break when filling is enabled and a mandatory break when
  it's not.
* Clarify use of `.TS H`.
* Say "front matter", not "front material".
* Clarify issue of AT&T device-independent troff extensions.

1 files changed, 19 insertions, 11 deletions

diff --git a/doc/meref.me.in b/doc/meref.me.in
index be88b95d8..acd8c895a 100644
--- a/doc/meref.me.in
+++ b/doc/meref.me.in
@@ -744,6 +744,7 @@ and if
 the list is centered on a line-by-line basis.
 If
 .i F
+[empty]
 is
 .b F ,
 filling is enabled.
@@ -912,7 +913,7 @@ the number is kept in
 and in the associated string
 .ST * .
 The text of the footnote
-is floated to the bottom
+floats to the bottom
 of the page
 and set in font
 .NR (ff
@@ -937,6 +938,7 @@ by
 [0].
 Footnotes line up underneath
 columns in the page layout.
+.\" XXX: Quantify when debugged.  See Savannah #58447, #63163, #63164.
 If the text of the footnote
 does not fit on the page,
 it is carried over
@@ -1120,8 +1122,8 @@ style or decorate an argument
 .i W
 and accept an optional second argument
 .i X,
-set in the previous style without intervening space.
-To concatenate several font styles within a word,
+formatted as the previous text without intervening space.
+To suppress a word break after the call,
 populate or suffix
 .i X
 with
@@ -1259,6 +1261,7 @@ and if
 .b L ,
 left-aligned.
 .i T
+[empty]
 is a title aligned to the right margin
 next to the equation.
 See
@@ -1274,6 +1277,7 @@ End
 equation.
 If
 .i C
+[empty]
 is
 .b C ,
 and the equation is followed immediately
@@ -1298,13 +1302,15 @@ table.
 Tables are preceded and followed by
 .NR (bs
 of space.
-Specify
-.b H
-for
+If
 .i H
-and call
+[empty]
+is
+.b H ,
+you can call
 .b .TH
-subsequently to repeat a table header across columns or pages.
+after the table header
+to repeat it across columns or pages.
 If you want a table to float,
 surround the
 .b .TS
@@ -1520,7 +1526,7 @@ should be preceded by a
 .b .+c
 call.
 It is easier when using
-\*T to put the front material
+\*T to put the front matter
 at the end of the paper,
 so that the table of contents
 can be collected and put out;
@@ -1799,6 +1805,7 @@ Equivalent to \(lq\fB.af % 1\fP\(rq.
 Number output lines starting from 1.
 If
 .i C
+[empty]
 is
 .b C ,
 the line length is reduced
@@ -2130,8 +2137,9 @@ The dagger \(dg and double dagger \(dd identify user-definable macros.
 Those marked with
 \(dd have default definitions;
 changing them may have unexpected side effects.
-The degree sign \(de notes a feature introduced in AT&T
-device-independent \*T,
+The degree sign \(de notes features requiring AT&T device-independent
+\*T extensions
+(ca. 1981),
 and a square \(sq labels \*G extensions.
 .de $H
 .ev 1