[groff] 08/20: tbl(1): Further document nroff mode limitations.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 9033494f6c08f67df1bb70549c3f7c807ebb0a8f
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Fri Feb 3 01:43:11 2023 -0600

    tbl(1): Further document nroff mode limitations.
    
    See Savannah #63749.
    
    Also consistently use the term "rule" instead of "line" (albeit with
    parenthetical clarification).  The value of the term "rule" is that it
    is not confusable with "lines" of (text) input or output.
---
 src/preproc/tbl/tbl.1.man | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/preproc/tbl/tbl.1.man b/src/preproc/tbl/tbl.1.man
index 65c2d5e7b..7ffc086ab 100644
--- a/src/preproc/tbl/tbl.1.man
+++ b/src/preproc/tbl/tbl.1.man
@@ -10,7 +10,7 @@ documents
 .\" Legal Terms
 .\" ====================================================================
 .\"
-.\" Copyright (C) 1989-2021 Free Software Foundation, Inc.
+.\" Copyright (C) 1989-2023 Free Software Foundation, Inc.
 .\"
 .\" Permission is granted to make and distribute verbatim copies of this
 .\" manual provided the copyright notice and this permission notice are
@@ -637,7 +637,7 @@ issues a diagnostic message.
 .
 .TP
 .B |
-Place a vertical rule on the corresponding row of the table
+Place a vertical rule (line) on the corresponding row of the table
 (if two of these are adjacent,
 a double vertical rule).
 .
@@ -647,7 +647,10 @@ entries correspond to it.
 A
 .B |
 to the left of the first column descriptor or to the right of the last
-one produces a line at the edge of the table.
+one produces a vertical rule at the edge of the table;
+these are redundant
+(and ignored)
+in boxed tables.
 .
 .
 .P
@@ -1559,7 +1562,7 @@ See section \[lq]Examples\[rq] below for a demonstration.
 .
 .
 .P
-Double horizontal rules are not currently supported by
+Double horizontal rules are not supported by
 .MR grotty @MAN1EXT@ ;
 single rules are used instead.
 .
@@ -1569,7 +1572,8 @@ so the
 .B u
 column modifier has no effect.
 .
-On terminal devices,
+On terminal devices
+.RI (\[lq] nroff mode\[rq]),
 horizontal rules and box borders occupy a full vee of space;
 this amount is doubled for
 .B doublebox
@@ -1584,6 +1588,12 @@ write
 .B ne
 requests accordingly.
 .
+Vertical rules between columns are drawn in the space between columns in
+.I nroff
+mode;
+using double vertical rules and/or reducing the column separation below
+the default can make them ugly or overstrike them with table data.
+.
 .
 .P
 A text block within a table must be able to fit on one page.