[groff] 34/41: groff_char(7): Fix content nits.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit db02fba94993a9964b1e464e86cf73bb601dbd60
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Mar 17 11:38:19 2022 +1100

    groff_char(7): Fix content nits.
    
    * Explicitly identify what "automatically" loads "composite.tmac".
    * Fix bug in logical symbols table to show the output distinction (if
      any) between | and \[or].
    * It is now less certain that the square became filled in the bold font.
    * Explain why the plus, minus, and equals sign appeared in the original
      AT&T "special" font, and indirectly why so much fuss is made about
      these three glyphs today (on top of dash/hyphen/minus confustion).
    * Document original mnemonic for \[bv] in a comment, because it would be
      misleading today.
    * Clarify what "composite.tmac" does.
    * Migrate terminology: "escape" -> "escape sequence".
---
 man/groff_char.7.man | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/man/groff_char.7.man b/man/groff_char.7.man
index 0c0cf2c8..42cd81e8 100644
--- a/man/groff_char.7.man
+++ b/man/groff_char.7.man
@@ -1879,7 +1879,11 @@ The glyph resembling an underscore is a baseline rule,
 and that resembling a vertical line is a box rule.
 .
 In bold,
+according to some sources,
 the square became filled.
+.\" In the Holt, Reinhart, Winston edition of the _Unix Programmer's
+.\" Manual_, Revised and Expanded Version, Volume 2 (1983), the square
+.\" in Times bold is _not_ shown as filled on page 226.  -- GBR
 .
 In italics,
 the box rule was not slanted.
@@ -1906,6 +1910,19 @@ The special font supplied the missing ASCII and Teletype 
extended
 glyphs,
 among several others.
 .
+The plus,
+minus,
+and equals signs appeared in the special font despite availability in
+text fonts \[lq]to insulate the appearance of equations from the choice
+of standard [read: text] fonts\[rq].
+.
+Recall that
+.I troff \" AT&T
+was turned to the task of mathematical typesetting as soon as it was
+developed.
+.
+.
+.P
 We note that AT&T took the opportunity to de-unify the apostrophe
 and acute accent
 (a choice ISO later duplicated in its 8859 series of standards).
@@ -1947,6 +1964,11 @@ No equivalent was available on the C/A/T;
 the box rule
 .BR \[rs][br] ,
 brace vertical extension
+.\" CSTR #54 (1976 edition) called this the "bold vertical", probably
+.\" because it was thicker than the box rule and matched the thickness
+.\" of the bracket pieces \(lt, \(lb, \(rt, \(rb, \(lk, \(rk, and so on.
+.\" Saying "bold" could be misleading because it appeared only in the
+.\" special font, not a bold text font.
 .BR \[rs][bv] ,
 and \[lq]or\[rq] operator
 .BR \[rs][or] ,
@@ -1963,8 +1985,8 @@ The files below are loaded automatically by the default
 .
 .TP
 .I @MACRODIR@/\:\%composite\:.tmac
-assigns mappings for glyphs after the first in a composite special
-character.
+assigns alternate mappings for identifiers after the first in a
+composite special character escape sequence.
 .
 See subsection \[lq]Accents\[rq] above.
 .