Add new escape \F to switch font family.

* src/roff/troff/input.cc (token::next): Handle \F.
* src/roff/troff/env.cc (environment::set_family): Handle
`interrupted' flag.
* NEWS, doc/groff.texinfo, man/groff_diff.man, man/groff.man:
Document it.

* tmac/doc.tmac (doc-tag-list): Use \Z to avoid stretching of
spaces in tags.

* tmac/Xps.tmac: Remove some redundant code.

* tmac/doc-common, tmac/doc-ditroff, tmac/doc-nroff, tmac/doc.tmac,
tmac/dvi.tmac, contrib/groffer/groffer.man, man/roff.man,
man/groff_out.man, man/groff.man, man/groff_diff.man,
src/roff/groff/groff.man: Replace \f[P] with \f[].

4 files changed, 13 insertions, 3 deletions

diff --git a/src/devices/grotty/grotty.man b/src/devices/grotty/grotty.man
index 214b8147..3be01b96 100644
--- a/src/devices/grotty/grotty.man
+++ b/src/devices/grotty/grotty.man
@@ -74,7 +74,7 @@ emits SGR escape sequences (from ISO 6429, also called ANSI color escapes)
 to change text attributes (bold, italic, colors).
 This makes it possible to have have eight different \M[green]background\M[]
 and \m[red]foreground\m[] colors; additionally, bold and italic
-attributes can be used \f[BI]at the same time\f[P] (by using the BI font).
+attributes can be used \f[BI]at the same time\f[] (by using the BI font).
 .LP
 The following colors are defined in
 .BR tty.tmac :
diff --git a/src/roff/groff/groff.man b/src/roff/groff/groff.man
index baad66fc..00d98c1d 100644
--- a/src/roff/groff/groff.man
+++ b/src/roff/groff/groff.man
@@ -193,7 +193,7 @@ FDL in the main directory of the groff source package.
 .de ShellCommand
 .  ad l
 .  I shell#
-.  nop \f[CB]\$*\f[P]
+.  nop \f[CB]\$*\f[]
 .  ad
 ..
 .\" --------------------------------------------------------------------
diff --git a/src/roff/troff/env.cc b/src/roff/troff/env.cc
index 7e1cc734..ede6b78c 100644
--- a/src/roff/troff/env.cc
+++ b/src/roff/troff/env.cc
@@ -479,7 +479,9 @@ void environment::set_font(int n)
 
 void environment::set_family(symbol fam)
 {
-  if (fam.is_null()) {
+  if (interrupted)
+    return;
+  if (fam.is_null() || fam.is_empty()) {
     if (prev_family->make_definite(fontno) < 0)
       return;
     font_family *tem = family;
diff --git a/src/roff/troff/input.cc b/src/roff/troff/input.cc
index 0ddbc10b..446bc3d5 100644
--- a/src/roff/troff/input.cc
+++ b/src/roff/troff/input.cc
@@ -1806,6 +1806,14 @@ void token::next()
 	    have_input = 1;
 	  break;
 	}
+      case 'F':
+	{
+	  symbol s = read_escape_name(0);
+	  if (s.is_null())
+	    break;
+	  curenv->set_family(s);
+	  break;
+	}
       case 'g':
 	{
 	  symbol s = read_escape_name();