[groff] 09/09: [ms]: Document origin/portability of .BI.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 8273b0155ea57ac2e0cdab0053295e9f3993c94a
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Apr 29 21:10:18 2021 +1000

    [ms]: Document origin/portability of .BI.
    
    The availability of a bold-italic style for nearly any font family,
    taken for granted in the PostScript era, is a late development relative
    to AT&T troff and ms.  The V7 Unix and 4.2BSD ms implementations lack
    the macro altogether.
    
    V10 Research Unix has it, with a terse comment: "only on 202"; I surmise
    that this is a reference to the equipment memorialized in the 1980
    Condon/Kernighan/Thompson paper "Experience with the Mergenthaler
    Linotron 202 Phototypesetter, or, How We Spent Our Summer Vacation"
    <https://www.cs.princeton.edu/~bwk/202/index.html>.
---
 doc/groff.texi      | 3 ++-
 doc/ms.ms           | 3 +++
 tmac/groff_ms.7.man | 3 +++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/doc/groff.texi b/doc/groff.texi
index 81d672e..b8d9504 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -3232,7 +3232,8 @@ to the @code{B}@tie{}macro otherwise.
 
 @Defmac {BI, [@Var{txt} [@Var{post} [@Var{pre}]]], ms}
 Sets its first argument in bold italic type.  It operates similarly to
-the @code{B}@tie{}macro otherwise.
+the @code{B}@tie{}macro otherwise.  This is a Version@tie{}10 Research
+Unix extension.
 @endDefmac
 
 @Defmac {CW, [@Var{txt} [@Var{post} [@Var{pre}]]], ms}
diff --git a/doc/ms.ms b/doc/ms.ms
index 0c45b34..88fc373 100644
--- a/doc/ms.ms
+++ b/doc/ms.ms
@@ -1192,6 +1192,9 @@ Sets its first argument in
 It operates similarly to the
 .CW .B
 macro otherwise.
+.
+This is a Version\~10 Research Unix extension.
+.\" possibly V9, but definitely not Berkeley
 T}
 _
 \&.CW [txt [post [pre]]]       T{
diff --git a/tmac/groff_ms.7.man b/tmac/groff_ms.7.man
index a20fbff..4337738 100644
--- a/tmac/groff_ms.7.man
+++ b/tmac/groff_ms.7.man
@@ -840,6 +840,9 @@ It operates similarly to the
 .B B
 macro otherwise.
 .
+This is a Version\~10 Research Unix extension.
+.\" Possibly V9, but definitely not Berkeley.
+.
 .
 .TP
 .B .CW\c