[groff] 03/16: [docs]: Document `.m` and `.M` registers better.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 1643e54a5b5b7ad4a27ce35bff14e9d264965271
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Wed Dec 14 10:55:01 2022 -0600

    [docs]: Document `.m` and `.M` registers better.
    
    Say what they do when the color is the default; they don't interpolate
    "default", even though that is the keyword you'd use with their
    counterpart requests and escape sequences.
---
 doc/groff.texi  | 6 ++++--
 man/groff.7.man | 4 ++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/doc/groff.texi b/doc/groff.texi
index 7b196ff47..8d4a92755 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -12013,7 +12013,8 @@ does a @code{gcolor} request without an argument.
 @cindex color name, stroke, register (@code{.m})
 The name of the current stroke color is available in the read-only
 string-valued register @samp{.m}; it is associated with the environment
-(@pxref{Environments}).
+(@pxref{Environments}).  It interpolates nothing when the stroke color
+is the default.
 
 @code{\m} doesn't produce an input token in GNU @code{troff}
 (@pxref{Gtroff Internals}).  It therefore can be used in requests like
@@ -12050,7 +12051,8 @@ does an @code{fcolor} request without an argument.
 @cindex color name, fill, register (@code{.M})
 The name of the current fill color is available in the read-only
 string-valued register @samp{.M}; it is associated with the environment
-(@pxref{Environments}).
+(@pxref{Environments}).  It interpolates nothing when the fill color
+is the default.
 
 @code{\M} doesn't produce an input token in GNU @code{troff}.
 @endDefesc
diff --git a/man/groff.7.man b/man/groff.7.man
index 53633b1bb..de03b0f87 100644
--- a/man/groff.7.man
+++ b/man/groff.7.man
@@ -5521,6 +5521,8 @@ see
 and
 .esc m .
 .
+Empty if the stroke color is the default.
+.
 .TP
 .REG .M
 Fill color (string-valued);
@@ -5529,6 +5531,8 @@ see
 and
 .esc M .
 .
+Empty if the fill color is the default.
+.
 .TP
 .REG .n
 Length of formatted output on previous output line.