[groff] 15/23: groff_mm(7) (Macros): Add introductory material.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit b39d29a1dd00595e173623e6431a05f70b558068
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Jul 28 14:48:14 2022 -0500

    groff_mm(7) (Macros): Add introductory material.
---
 contrib/mm/groff_mm.7.man | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/contrib/mm/groff_mm.7.man b/contrib/mm/groff_mm.7.man
index 626035554..99a2fef22 100644
--- a/contrib/mm/groff_mm.7.man
+++ b/contrib/mm/groff_mm.7.man
@@ -359,6 +359,28 @@ for instance with
 .SH Macros
 .\" ====================================================================
 .
+An explicitly empty argument may be specified with a pair of double
+quotes;
+to call a macro
+.B XX
+with an empty second argument but non-empty first and third ones,
+you could input the following.
+.
+.RS
+.EX
+\&.XX foo \[dq]\[dq] baz
+.EE
+.RE
+.
+.
+.P
+Macro names longer than two characters are GNU extensions;
+some shorter names were not part of DWB
+.IR mm 's
+published interface but are documented aspects of
+.I groff mm.
+.
+.
 .TP
 .BI )E\  "level text"
 Add heading text