tmac/papersize.tmac: Improve integration w/ mm(7).

* tmac/papersize.tmac: Improve integration with mm(7) macro package.  If
  a paper format has been selected, set `W` register to new line length
  (if not already set on command line).  Similarly, set `O` register to
  1 inch for the symmetric horizontal margins otherwise assumed by this
  macro file.  This means that "groff -mm" and "groff -dpaper=letter
  -mm" are _not_ synonymous (when groff is configured to use U.S. letter
  as the default paper format), because groff mm(7) uses a page offset
  of 0.963 inches on typesetters for compatibility with DWB mm.

* NEWS: Add item.

See discussion in <https://lists.gnu.org/archive/html/groff/2022-11/\
msg00081.html> and (some) follow-ups.

1 files changed, 10 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 0c1e1f079..599bcff7a 100644
--- a/NEWS
+++ b/NEWS
@@ -360,6 +360,16 @@ o The e (me) and s (ms) macro packages now offer a `PF` macro,
   supporting the pic(1) preprocessor's "flyback" feature.  Thanks to
   Dave Kemper.
 
+o The m (mm) macro package now adapts to the paper format selected when
+  the macro file "papersize.tmac" is used (by specifying the groff "-d
+  paper" command-line option).  A consequence is that "groff -mm" and
+  "groff -d paper=letter -mm" are _not_ synonymous (when groff is
+  configured to use U.S. letter as the default paper format), because
+  groff mm(7) uses a page offset of 0.963 inches on typesetters for
+  compatibility with DWB mm.  If the `W` or `O` registers are also set
+  on the command line, the line length and page offset, respectively,
+  are not overridden.
+
 o The m (mm) macro package now recognizes a `V` register to set the
   vertical spacing for the document.  Like the existing `S`, it must be
   set from the command line.  Further, both registers are interpreted