Implement \f[] as an alternative to \fP. Change \mP and \MP to

\m[] and \M[], respectively.

* src/roff/troff/symbol.cc (EMPTY_SYMBOL): New global variable.
(symbol::symbol): Handle NULL string and empty string differently.
* src/roff/troff/symbol.h (symbol::is_empty): New inline function.
* src/roff/troff/input.cc (read_escape_name, read_long_escape_name):
Add optional parameter.
Updated calling functions.
(get_copy, do_glyph_color, do_fill_color, token::next): Use
`symbol::is_empty'.
* src/roff/troff/env.cc (environment::set_font): Ditto.

* src/preproc/pic/troff.cc (troff_output::set_fill,
troff_output::reset_color: Updated.

* tmac/www.tmac: Updated.

* NEWS, man/groff_diff.man, man/groff.man, doc/groff.texinfo,
doc/homepage.ms, src/devices/grotty/grotty.man, tmac/groff_www.man:
Updated.

* src/include/printer.h, src/libs/libdriver/printer.cc
(printer::change_fill_color): New member function.
* src/libs/libdriver/input.cc (parse_D_command): Use it.

17 files changed, 220 insertions, 114 deletions

diff --git a/ChangeLog b/ChangeLog
index 22fb8aca..fee1f1cf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,33 @@
+2002-04-13  Werner LEMBERG  <wl@gnu.org>
+
+	Implement \f[] as an alternative to \fP.  Change \mP and \MP to
+	\m[] and \M[], respectively.
+
+	* src/roff/troff/symbol.cc (EMPTY_SYMBOL): New global variable.
+	(symbol::symbol): Handle NULL string and empty string differently.
+	* src/roff/troff/symbol.h (symbol::is_empty): New inline function.
+	* src/roff/troff/input.cc (read_escape_name, read_long_escape_name):
+	Add optional parameter.
+	Updated calling functions.
+	(get_copy, do_glyph_color, do_fill_color, token::next): Use
+	`symbol::is_empty'.
+	* src/roff/troff/env.cc (environment::set_font): Ditto.
+
+	* src/preproc/pic/troff.cc (troff_output::set_fill,
+	troff_output::reset_color: Updated.
+
+	* tmac/www.tmac: Updated.
+
+	* NEWS, man/groff_diff.man, man/groff.man, doc/groff.texinfo,
+	doc/homepage.ms, src/devices/grotty/grotty.man, tmac/groff_www.man:
+	Updated.
+
+2002-04-13  Bernd Warken  <bwarken@mayn.de>
+
+	* src/include/printer.h, src/libs/libdriver/printer.cc
+	(printer::change_fill_color): New member function.
+	* src/libs/libdriver/input.cc (parse_D_command): Use it.
+
 2002-04-12  Werner LEMBERG  <wl@gnu.org>
 
 	* doc/groff.texinfo: Completed pass on gtroff reference.
diff --git a/NEWS b/NEWS
index 7c226e18..37f8d5ed 100644
--- a/NEWS
+++ b/NEWS
@@ -18,10 +18,10 @@ o Color support has been added to troff and pic (and to the device drivers
   follow).  A new function `defcolor' defines colors; the escape sequence
   `\m' sets the drawing color, the escape sequence `\M' specifies the
   background color for closed objects created with \D'...' commands. 
-  Similar to fonts, `\mP' and `\MP' switch back to the previous color.  `\m'
-  and `\M' correspond to the new troff output command sets starting with `m'
-  and `DF'.  The device-specific default color is called `default' and can't
-  be redefined.
+  `\m[]' and `\M[]' switch back to the previous color.  `\m' and `\M'
+  correspond to the new troff output command sets starting with `m' and
+  `DF'.  The device-specific default color is called `default' and can't be
+  redefined.
 
   The old `Df' output command is mapped onto `DFg'; all color output
   commands don't change the current font position (consequently, `Df'
@@ -39,6 +39,9 @@ o Color support has been added to troff and pic (and to the device drivers
   More details can be found in the groff_diff.7 manual page and in
   groff.texinfo.
 
+o Similar to \m and \M, \f[] switches back to the previous font.  \fP
+  (and \f[P]) is still valid for backwards compatibility.
+
 o Two new glyph symbols are available: `eu' is the official Euro symbol;
   `Eu' is a font-specific glyph variant.
 
diff --git a/doc/groff.texinfo b/doc/groff.texinfo
index 05d5727e..0f1c5ad1 100644
--- a/doc/groff.texinfo
+++ b/doc/groff.texinfo
@@ -7516,11 +7516,11 @@ with the @code{styles} command in the @file{DESC} file), use it within
 the current font family (as set with the @code{fam} request or with
 the @code{family} command in the @file{DESC} file).
 
-@cindex previous font (@code{ft}, @code{\fP})
-@cindex font, previous (@code{ft}, @code{\fP})
+@cindex previous font (@code{ft}, @code{\f[]}, @code{\fP})
+@cindex font, previous (@code{ft}, @code{\f[]}, @code{\fP})
 With no argument or using @samp{P} as an argument, @code{.ft} switches
-to the previous font.  Use @code{\fP} or @code{\f[P]} to do this with
-the escape.
+to the previous font.  Use @code{\f[]} to do this with the escape.  The
+old syntax forms @code{\fP} or @code{\f[P]} are also supported.
 
 Fonts are generally specified as upper-case strings, which are usually
 1@w{ }to 4 characters representing an abbreviation or acronym of the
@@ -7544,7 +7544,7 @@ expects a single character as an argument) to change the font on
 the fly:
 
 @Example
-.mc \f[I]x\f[P]
+.mc \f[I]x\f[]
 @endExample
 
 @xref{Font Positions}, for an alternative syntax.
@@ -10866,10 +10866,10 @@ Set drawing color.  The following example shows how to turn the next four
 words red.
 
 @Example
-\m[red]these are in red\mP and these words are in black.
+\m[red]these are in red\m[] and these words are in black.
 @endExample
 
-The escape @code{\mP} returns to the previous color.
+The escape @code{\m[]} returns to the previous color.
 
 The drawing color is associated with the current environment
 (@pxref{Environments}).
@@ -10884,10 +10884,10 @@ Set background color for filled objects drawn with the
 A red ellipse can be created with the following code:
 
 @Example
-\M[red]\h'0.5i'\D'E 2i 1i'\Mp
+\M[red]\h'0.5i'\D'E 2i 1i'\M[]
 @endExample
 
-The escape @code{\MP} returns to the previous fill color.
+The escape @code{\M[]} returns to the previous fill color.
 
 The fill color is associated with the current environment
 (@pxref{Environments}).
diff --git a/doc/homepage.ms b/doc/homepage.ms
index b4668ffd..6bc07b1d 100755
--- a/doc/homepage.ms
+++ b/doc/homepage.ms
@@ -24,7 +24,7 @@
 .defcolor darkgreen rgb 0.1f 0.5f 0.2f
 .defcolor darkblue rgb 0.1f 0.2f 0.6f
 .
-.ds GNU \m[darkred]G\mP\m[darkgreen]N\mP\m[darkblue]U\mP
+.ds GNU \m[darkred]G\m[]\m[darkgreen]N\m[]\m[darkblue]U\m[]
 .
 .HTL
 .
diff --git a/man/groff.man b/man/groff.man
index 8fd71ef4..71ae61ca 100644
--- a/man/groff.man
+++ b/man/groff.man
@@ -2,7 +2,7 @@
 .ig
 groff.man
 
-Last update: 15 Mar 2002
+Last update: 14 Apr 2002
 
 This file is part of groff, the GNU roff type-setting system.
 
@@ -1543,6 +1543,8 @@ will be special.
 .REQ .ft
 Return to previous font.
 Same as
+.request \[rs]f[]
+or
 .request \[rs]fP .
 .
 .REQ .ft font
@@ -2514,6 +2516,9 @@ Equivalent to an escape character, but is not interpreted in copy-mode.
 Change to font with 1-character name or 1-digit number
 .IR F .
 .
+.ESC fP
+Switch back to previous font.
+.
 .ESC f( fo
 Change to font with 2-characer name or 2-digit number
 .IR fo .
@@ -2522,6 +2527,9 @@ Change to font with 2-characer name or 2-digit number
 Change to font with arbitrary length name or number expression
 .IR font .
 .
+.ESC[] f ""
+Switch back to previous font.
+.
 .ESC[] g reg
 Return format of register with name
 .I reg
@@ -2567,6 +2575,9 @@ Alternative forms
 and
 .escarg m c .
 .
+.ESC[] m ""
+Switch back to previous color.
+.
 .ESC[] M color
 Change filling color for closed drawn objects to color
 .IR color .
@@ -2576,6 +2587,9 @@ Alternative forms
 and
 .escarg M c .
 .
+.ESC[] M ""
+Switch to previous fill color.
+.
 .ESC n r
 The numerical value stored in the register variable with the
 1-character name
diff --git a/man/groff_diff.man b/man/groff_diff.man
index f2564848..f39b2506 100644
--- a/man/groff_diff.man
+++ b/man/groff_diff.man
@@ -3,7 +3,7 @@
 .ig
 groff_diff.man
 
-Last update : 6 Jan 2002
+Last update : 14 Apr 2002
 
 This file is part of groff, the GNU roff type-setting system.
 It is the source of the man-page groff_diff(7).
@@ -185,6 +185,12 @@ Print the special character called
 Set font
 .IR xxx .
 .
+Additionally,
+.B \[rs]f[]
+is a new syntax equal to
+.BR \[rs]fP ,
+i.e., to return to the previous font.
+.
 .TP
 .BI \[rs]*[ xxx ]
 Interpolate string
@@ -414,7 +420,7 @@ argument).
 .TQ
 .BI \[rs]m[ xxx ]
 Set drawing color.
-.B \[rs]mP
+.B \[rs]m[]
 switches back to the previous color.
 .
 .TP
@@ -426,7 +432,7 @@ switches back to the previous color.
 Set background color for filled objects drawn with the
 .BI \[rs]D' .\|.\|. '
 commands.
-.B \[rs]MP
+.B \[rs]M[]
 switches back to the previous color.
 .
 .TP
diff --git a/src/devices/grotty/grotty.man b/src/devices/grotty/grotty.man
index 0f0e24e9..214b8147 100644
--- a/src/devices/grotty/grotty.man
+++ b/src/devices/grotty/grotty.man
@@ -72,8 +72,8 @@ By default,
 .B grotty
 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[P]
-and \m[red]foreground\m[P] colors; additionally, bold and italic
+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).
 .LP
 The following colors are defined in
diff --git a/src/include/printer.h b/src/include/printer.h
index 726277b9..4d5cbf52 100644
--- a/src/include/printer.h
+++ b/src/include/printer.h
@@ -1,23 +1,40 @@
 // -*- C++ -*-
+
+// <groff_src_dir>/src/include/printer.h
+
 /* Copyright (C) 1989, 1990, 1991, 1992, 2001, 2002
    Free Software Foundation, Inc.
-     Written by James Clark (jjc@jclark.com)
 
-This file is part of groff.
+   Written by James Clark (jjc@jclark.com)
+
+   Last update: 12 Apr 2002
+
+   This file is part of groff.
+
+   groff is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   groff is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
 
-groff is free software; you can redistribute it and/or modify it under
-the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
-version.
+   You should have received a copy of the GNU General Public License
+   along with groff; see the file COPYING.  If not, write to the Free
+   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.
+*/
 
-groff is distributed in the hope that it will be useful, but WITHOUT ANY
-WARRANTY; without even the implied warranty of MERCHANTABILITY or
-FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-for more details.
+/* Description
 
-You should have received a copy of the GNU General Public License along
-with groff; see the file COPYING.  If not, write to the Free Software
-Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+   The class `printer' performs the postprocessing.  Each
+   postprocessor only need to implement a derived class of `printer' and
+   a suitable function `make_printer' for the device-dependent tasks.
+   Then the methods of class `printer' are called automatically by
+   `do_file()' in `input.cc'.
+*/
 
 #include "color.h"
 
@@ -50,17 +67,22 @@ public:
 		      int *widthp = 0);
   void set_special_char(const char *nm, const environment *env,
 			int *widthp = 0);
-  void set_numbered_char(int n, const environment *env, int *widthp = 0);
+  void set_numbered_char(int n, const environment *env,
+			 int *widthp = 0);
   int set_char_and_width(const char *nm, const environment *env,
 			 int *widthp, font **f);
   font *get_font_from_index(int fontno);
   virtual void draw(int code, int *p, int np, const environment *env);
-  virtual void change_color(const environment *env);
+  // perform change of line color (text, outline) in the print-out 
+  virtual void change_color(const environment * const env);
+  // perform change of fill color in the print-out 
+  virtual void change_fill_color(const environment * const env);
   virtual void begin_page(int) = 0;
   virtual void end_page(int page_length) = 0;
   virtual font *make_font(const char *nm);
   virtual void end_of_line();
-  virtual void special(char *arg, const environment *env, char type = 'p');
+  virtual void special(char *arg, const environment *env,
+		       char type = 'p');
 protected:
   font_pointer_list *font_list;
 
diff --git a/src/libs/libdriver/input.cc b/src/libs/libdriver/input.cc
index 697af23b..7008ee8d 100644
--- a/src/libs/libdriver/input.cc
+++ b/src/libs/libdriver/input.cc
@@ -8,7 +8,7 @@
    Written by James Clark (jjc@jclark.com)
    Major rewrite 2001 by Bernd Warken (bwarken@mayn.de)
 
-   Last update: 10 Apr 2002
+   Last update: 12 Apr 2002
 
    This file is part of groff, the GNU roff text processing system.
 
@@ -60,6 +60,7 @@
    - Unknown subcommands of `D' and `x' are now ignored like in the
      classical case, but a warning is issued.  This was also
      implemented for the other commands.
+   - A warning is emitted if `x stop' is missing.
    - `DC' and `DE' commands didn't position to the right end after
      drawing (now they do), see discussion below.
    - So far, `x stop' was ignored.  Now it terminates the processing
@@ -85,16 +86,12 @@
      checks whether its argument agrees with the file name used so far,
      otherwise a warning is issued.  Then the new name is remembered
      and used for the following error messages.
-   - Positioning of drawing commands is corrected according to the
-     classical rule, see the discussion below.
-     - Setting commands (`Dt', `Df', `DF') and polygons (`Dp' and `DP')
-       do not change position now.
-     - Filled circles and ellipses (`DC' and `DE') position at their
-       most right point (outlined ones `Dc' and `De' did this anyway).
-     - As before, all open graphical objects position to their final
-       drawing point (alternate sum of the command arguments).
-     There is a macro STUPID_DRAWING_POSITIONING that implements the
-     old behavior for testing purposes.
+   - For the positioning after drawing commands, an alternative, easier
+     scheme is provided, but not yet activated; it can be chosen by
+     undefining the preprocessor macro STUPID_DRAWING_POSITIONING.
+     It extends the rule of the classical troff output language in a
+     logical way instead of the rather strange actual positioning.
+     For details, see the discussion below.
    - For the `D' commands that only set the environment, the calling of
      pr->send_draw() was removed because this doesn't make sense for
      the `DF' commands; the (changed) environment is sent with the
@@ -138,19 +135,18 @@
    - Various comments were added.
 
    TODO
-   - Add scaling facility for classical device independence and
-     non-groff devices.
-   - Should a missing `x stop' be warned?
    - Get rid of the stupid drawing positioning.
    - Can the `Dt' command be completely handled by setting environment
      within do_file() instead of sending to pr?
    - Integer arguments must be >= 32 bits, use conditional #define.
-   - Classical troff output had a quasi device independence by scaling
-     the intermediate output to the resolution of the postprocessor
-     device if different from the one specified with `x T', groff does
-     not.  So implement full quasi device indepedence, including
-     the mapping of the strange classical devices to the postprocessor
-     device (seems to be reasonably easy).
+   - Add scaling facility for classical device independence and
+     non-groff devices.  Classical troff output had a quasi device
+     independence by scaling the intermediate output to the resolution
+     of the postprocessor device if different from the one specified
+     with `x T', groff have not.  So implement full quasi device
+     indepedence, including the mapping of the strange classical
+     devices to the postprocessor device (seems to be reasonably
+     easy).
    - The external, global pointer variables are not optimally handled.
      - `pr' isn't used outside besides initialization and deletion.
        So it could be replaced by a static local variable.  For
@@ -159,14 +155,16 @@
      - The global variables `current_filename' and `current_lineno' are
        only used for error reporting.  So implement a static class
        `Error' (`::' calls).
-     - Stop using global `device'; design a new scheme based on
-       postprocessors.
+     - The global `device' is the name used during the formatting
+       process; there should be a new variable for the device name used
+       during the postprocessing.
   - Implement the B-spline drawing `D~' for all graphical devices.
   - Make `environment' a class with an overflow check for its members
     and a delete method to get rid of delete_current_env().
+  - Implement the `EnvStack' to use `new' instead of `malloc'.
   - The class definitions of this document could go into a new file.
-  - Once things will have been settled the comments in this document
-    could be strongly reduced.
+  - The comments in this section should go to a `Changelog' or some
+    `README' file in this directory.
 */
 
 /*
@@ -229,6 +227,15 @@
   classical specification with its clear end-of-drawing rule that is
   suitable for all cases.  But a macro STUPID_DRAWING_POSITIONING is
   provided for testing the funny former behavior.
+
+  The new rule implies the following behavior.
+  - Setting commands (`Dt', `Df', `DF') and polygons (`Dp' and `DP')
+    do not change position now.
+  - Filled circles and ellipses (`DC' and `DE') position at their
+    most right point (outlined ones `Dc' and `De' did this anyway).
+  - As before, all open graphical objects position to their final
+    drawing point (alternate sum of the command arguments).
+
 */
 
 #ifndef STUPID_DRAWING_POSITIONING
@@ -1353,7 +1360,7 @@ parse_D_command()
 	delete current_env->fill;
 	current_env->fill = new color(current_env->col);
       }
-      pr->change_color(current_env);
+      pr->change_fill_color(current_env);
       // skip unused `vertical' component (\D'...' always emits pairs)
       (void) get_integer_arg();
       // no positioning
@@ -1362,7 +1369,7 @@ parse_D_command()
     }
   case 'F':			// DF: set fill color, several formats
     parse_color_command(current_env->fill);
-    pr->change_color(current_env);
+    pr->change_fill_color(current_env);
     // no positioning (setting-only command)
     skip_line_x();
     break;
diff --git a/src/libs/libdriver/printer.cc b/src/libs/libdriver/printer.cc
index 922f0b5f..c97e2ce6 100644
--- a/src/libs/libdriver/printer.cc
+++ b/src/libs/libdriver/printer.cc
@@ -1,23 +1,30 @@
 // -*- C++ -*-
+
+// <groff_src_dir>/src/libs/libdriver/printer.cc
+
 /* Copyright (C) 1989, 1990, 1991, 1992, 2001, 2002
    Free Software Foundation, Inc.
-     Written by James Clark (jjc@jclark.com)
+   Written by James Clark (jjc@jclark.com)
+
+   Last update: 12 Apr 2002
 
-This file is part of groff.
+   This file is part of groff.
 
-groff is free software; you can redistribute it and/or modify it under
-the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
-version.
+   groff is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
 
-groff is distributed in the hope that it will be useful, but WITHOUT ANY
-WARRANTY; without even the implied warranty of MERCHANTABILITY or
-FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-for more details.
+   groff is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
 
-You should have received a copy of the GNU General Public License along
-with groff; see the file COPYING.  If not, write to the Free Software
-Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+   You should have received a copy of the GNU General Public License
+   along with groff; see the file COPYING.  If not, write to the Free
+   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.
+*/
 
 #include "driver.h"
 
@@ -110,6 +117,10 @@ void printer::change_color(const environment *)
 {
 }
 
+void printer::change_fill_color(const environment *)
+{
+}
+
 void printer::set_ascii_char(unsigned char c, const environment *env, 
 			     int *widthp)
 {
diff --git a/src/preproc/pic/troff.cc b/src/preproc/pic/troff.cc
index 469ffa20..7ee7293f 100644
--- a/src/preproc/pic/troff.cc
+++ b/src/preproc/pic/troff.cc
@@ -484,7 +484,7 @@ void troff_output::set_fill(double f)
   if (last_filled) {
     free(last_filled);
     last_filled = 0;
-    printf("\\MP\n.sp -1\n");
+    printf("\\M[]\n.sp -1\n");
   }
 }
 
@@ -509,12 +509,12 @@ void troff_output::reset_color()
 {
   if (driver_extension_flag) {
     if (last_filled) {
-      printf("\\MP\n.sp -1\n");
+      printf("\\M[]\n.sp -1\n");
       free(last_filled);
       last_filled = 0;
     }
     if (last_outlined) {
-      printf("\\mP\n.sp -1\n");
+      printf("\\m[]\n.sp -1\n");
       free(last_outlined);
       last_outlined = 0;
     }
diff --git a/src/roff/troff/env.cc b/src/roff/troff/env.cc
index 933f68f9..7e1cc734 100644
--- a/src/roff/troff/env.cc
+++ b/src/roff/troff/env.cc
@@ -438,7 +438,7 @@ void environment::set_font(symbol nm)
 {
   if (interrupted)
     return;
-  if (nm == symbol("P")) {
+  if (nm == symbol("P") || nm.is_empty()) {
     if (family->make_definite(prev_fontno) < 0)
       return;
     int tem = fontno;
diff --git a/src/roff/troff/input.cc b/src/roff/troff/input.cc
index 19817f5e..0ddbc10b 100644
--- a/src/roff/troff/input.cc
+++ b/src/roff/troff/input.cc
@@ -130,7 +130,8 @@ static void copy_mode_error(const char *,
 			    const errarg & = empty_errarg,
 			    const errarg & = empty_errarg);
 
-static symbol read_escape_name();
+static symbol read_escape_name(int no_empty = 1);
+static symbol read_long_escape_name(int no_empty = 1);
 static void interpolate_string(symbol);
 static void interpolate_macro(symbol);
 static void interpolate_number_format(symbol);
@@ -724,7 +725,7 @@ static symbol read_two_char_escape_name()
   return symbol(buf);
 }
 
-static symbol read_long_escape_name()
+static symbol read_long_escape_name(int no_empty)
 {
   int start_level = input_stack::get_level();
   char abuf[ABUF_SIZE];
@@ -759,8 +760,9 @@ static symbol read_long_escape_name()
   buf[i] = 0;
   if (buf == abuf) {
     if (i == 0) {
-      copy_mode_error("empty escape name");
-      return NULL_SYMBOL;
+      if (no_empty)
+        copy_mode_error("empty escape name");
+      return EMPTY_SYMBOL;
     }
     return symbol(abuf);
   }
@@ -771,7 +773,7 @@ static symbol read_long_escape_name()
   }
 }
 
-static symbol read_escape_name()
+static symbol read_escape_name(int no_empty)
 {
   int c = get_char_for_escape_name();
   if (c == 0)
@@ -779,7 +781,7 @@ static symbol read_escape_name()
   if (c == '(')
     return read_two_char_escape_name();
   if (c == '[' && !compatible_flag)
-    return read_long_escape_name();
+    return read_long_escape_name(no_empty);
   char buf[2];
   buf[0] = c;
   buf[1] = '\0';
@@ -848,7 +850,7 @@ static int get_copy(node **nd, int defining)
       {
 	(void)input_stack::get(0);
 	symbol s = read_escape_name();
-	if (!s.is_null())
+	if (!(s.is_null() || s.is_empty()))
 	  interpolate_arg(s);
 	break;
       }
@@ -856,7 +858,7 @@ static int get_copy(node **nd, int defining)
       {
 	(void)input_stack::get(0);
 	symbol s = read_escape_name();
-	if (!s.is_null())
+	if (!(s.is_null() || s.is_empty()))
 	  interpolate_string(s);
 	break;
       }
@@ -874,7 +876,7 @@ static int get_copy(node **nd, int defining)
 	(void)input_stack::get(0);
 	int inc;
 	symbol s = read_increment_and_escape_name(&inc);
-	if (!s.is_null())
+	if (!(s.is_null() || s.is_empty()))
 	  interpolate_number_reg(s, inc);
 	break;
       }
@@ -882,7 +884,7 @@ static int get_copy(node **nd, int defining)
       {
 	(void)input_stack::get(0);
 	symbol s = read_escape_name();
-	if (!s.is_null())
+	if (!(s.is_null() || s.is_empty()))
 	  interpolate_number_format(s);
 	break;
       }
@@ -893,7 +895,7 @@ static int get_copy(node **nd, int defining)
       {
 	(void)input_stack::get(0);
 	symbol s = read_escape_name();
-	if (!s.is_null())
+	if (!(s.is_null() || s.is_empty()))
 	  interpolate_environment_variable(s);
 	break;
       }
@@ -1033,7 +1035,7 @@ static node *do_glyph_color(symbol nm)
 {
   if (nm.is_null())
     return 0;
-  if (nm == symbol("P"))
+  if (nm.is_empty())
     curenv->set_glyph_color(curenv->get_prev_glyph_color());
   else {
     color *tem = lookup_color(nm);
@@ -1049,7 +1051,7 @@ static node *do_fill_color(symbol nm)
 {
   if (nm.is_null())
     return 0;
-  if (nm == symbol("P"))
+  if (nm.is_empty())
     curenv->set_fill_color(curenv->get_prev_fill_color());
   else {
     color *tem = lookup_color(nm);
@@ -1738,14 +1740,14 @@ void token::next()
       case '$':
 	{
 	  symbol nm = read_escape_name();
-	  if (!nm.is_null())
+	  if (!(nm.is_null() || nm.is_empty()))
 	    interpolate_arg(nm);
 	  break;
 	}
       case '*':
 	{
 	  symbol nm = read_escape_name();
-	  if (!nm.is_null())
+	  if (!(nm.is_null() || nm.is_empty()))
 	    interpolate_string(nm);
 	  break;
 	}
@@ -1789,14 +1791,14 @@ void token::next()
 	goto handle_escape_char;
       case 'f':
 	{
-	  symbol s = read_escape_name();
+	  symbol s = read_escape_name(0);
 	  if (s.is_null())
 	    break;
 	  const char *p;
 	  for (p = s.contents(); *p != '\0'; p++)
 	    if (!csdigit(*p))
 	      break;
-	  if (*p)
+	  if (*p || s.is_empty())
 	    curenv->set_font(s);
 	  else
 	    curenv->set_font(atoi(s.contents()));
@@ -1807,7 +1809,7 @@ void token::next()
       case 'g':
 	{
 	  symbol s = read_escape_name();
-	  if (!s.is_null())
+	  if (!(s.is_null() || s.is_empty()))
 	    interpolate_number_format(s);
 	  break;
 	}
@@ -1825,7 +1827,7 @@ void token::next()
 	break;
       case 'k':
 	nm = read_escape_name();
-	if (nm.is_null())
+	if (nm.is_null() || nm.is_empty())
 	  break;
 	type = TOKEN_MARK_INPUT;
 	return;
@@ -1846,13 +1848,13 @@ void token::next()
 	  return;
 	}
       case 'm':
-	nd = do_glyph_color(read_escape_name());
+	nd = do_glyph_color(read_escape_name(0));
 	if (!nd)
 	  break;
 	type = TOKEN_NODE;
 	return;
       case 'M':
-	nd = do_fill_color(read_escape_name());
+	nd = do_fill_color(read_escape_name(0));
 	if (!nd)
 	  break;
 	type = TOKEN_NODE;
@@ -1861,7 +1863,7 @@ void token::next()
 	{
 	  int inc;
 	  symbol nm = read_increment_and_escape_name(&inc);
-	  if (!nm.is_null())
+	  if (!(nm.is_null() || nm.is_empty()))
 	    interpolate_number_reg(nm, inc);
 	  break;
 	}
@@ -1921,7 +1923,7 @@ void token::next()
       case 'V':
 	{
 	  symbol nm = read_escape_name();
-	  if (!nm.is_null())
+	  if (!(nm.is_null() || nm.is_empty()))
 	    interpolate_environment_variable(nm);
 	  break;
 	}
@@ -1943,7 +1945,7 @@ void token::next()
       case 'Y':
 	{
 	  symbol s = read_escape_name();
-	  if (s.is_null())
+	  if (s.is_null() || s.is_empty())
 	    break;
 	  request_or_macro *p = lookup_request(s);
 	  macro *m = p->to_macro();
@@ -1987,7 +1989,7 @@ void token::next()
       case '[':
 	if (!compatible_flag) {
 	  nm = read_long_escape_name();
-	  if (nm.is_null())
+	  if (nm.is_null() || nm.is_empty())
 	    break;
 	  type = TOKEN_SPECIAL;
 	  return;
@@ -4631,7 +4633,7 @@ extern int image_no;		// from node.cc
 
 static node *do_suppress(symbol nm)
 {
-  if (nm.is_null()) {
+  if (nm.is_null() || nm.is_empty()) {
     error("expecting an argument to escape \\O");
     return 0;
   }
diff --git a/src/roff/troff/symbol.cc b/src/roff/troff/symbol.cc
index ce09e393..6245301e 100644
--- a/src/roff/troff/symbol.cc
+++ b/src/roff/troff/symbol.cc
@@ -1,5 +1,5 @@
 // -*- C++ -*-
-/* Copyright (C) 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
+/* Copyright (C) 1989, 1990, 1991, 1992, 2002 Free Software Foundation, Inc.
      Written by James Clark (jjc@jclark.com)
 
 This file is part of groff.
@@ -29,6 +29,7 @@ char *symbol::block = 0;
 int symbol::block_size = 0;
 
 const symbol NULL_SYMBOL;
+const symbol EMPTY_SYMBOL("");
 
 #ifdef BLOCK_SIZE
 #undef BLOCK_SIZE
@@ -73,10 +74,14 @@ inline void unused(void *) { }
 
 symbol::symbol(const char *p, int how)
 {
-  if (p == 0 || *p == 0) {
+  if (p == 0) {
     s = 0;
     return;
   }
+  if (*p == 0) {
+    s = "";
+    return;
+  }
   if (table == 0) {
     table_size = table_sizes[0];
     table = (const char **)new char*[table_size];
@@ -147,4 +152,3 @@ symbol concat(symbol s1, symbol s2)
   a_delete buf;
   return res;
 }
-
diff --git a/src/roff/troff/symbol.h b/src/roff/troff/symbol.h
index 88e0fff3..5b7c9b19 100644
--- a/src/roff/troff/symbol.h
+++ b/src/roff/troff/symbol.h
@@ -1,5 +1,5 @@
 // -*- C++ -*-
-/* Copyright (C) 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
+/* Copyright (C) 1989, 1990, 1991, 1992, 2002 Free Software Foundation, Inc.
      Written by James Clark (jjc@jclark.com)
 
 This file is part of groff.
@@ -36,10 +36,12 @@ public:
   int operator !=(symbol) const;
   const char *contents() const;
   int is_null() const;
+  int is_empty() const;
 };
 
 
 extern const symbol NULL_SYMBOL;
+extern const symbol EMPTY_SYMBOL;
 
 inline symbol::symbol() : s(0)
 {
@@ -70,4 +72,9 @@ inline int symbol::is_null() const
   return s == 0;
 }
 
+inline int symbol::is_empty() const
+{
+  return s != 0 && *s == 0;
+}
+
 symbol concat(symbol, symbol);
diff --git a/tmac/groff_www.man b/tmac/groff_www.man
index e070c3ce..3ac6baab 100644
--- a/tmac/groff_www.man
+++ b/tmac/groff_www.man
@@ -155,7 +155,7 @@ If this is processed by a device other than
 it appears as:
 .RS
 .IP
-\m[blue]foo\mP \[la]\fChttp://foo.org\fP\[ra]:
+\m[blue]foo\m[] \[la]\fChttp://foo.org\fP\[ra]:
 .RE
 .IP
 The URL macro can be of any type; for example we can reference
diff --git a/tmac/www.tmac b/tmac/www.tmac
index 3d2d9351..479ea1e7 100644
--- a/tmac/www.tmac
+++ b/tmac/www.tmac
@@ -72,7 +72,7 @@
 .  ie \\n[www-html] \
 .    HTML <a href="\\$1">\\$2</a>\\$3
 .  el \
-.    nop \m[blue]\\$2\mP \%\[la]\fC\\$1\fP\[ra]\\$3
+.    nop \m[blue]\\$2\m[] \%\[la]\fC\\$1\fP\[ra]\\$3
 ..
 .\"
 .\" FTP url description [after]
@@ -105,9 +105,9 @@
 .  \}
 .  el \{\
 .    ie '\\$2'' \
-.      nop \%\m[blue]\fC\\$1\fP\mP\\$3
+.      nop \%\m[blue]\fC\\$1\fP\m[]\\$3
 .    el \
-.      nop \m[blue]\\$2\mP \%\[la]\fC\\$1\fP\[ra]\\$3
+.      nop \m[blue]\\$2\m[] \%\[la]\fC\\$1\fP\[ra]\\$3
 .  \}
 ..
 .\"
@@ -506,7 +506,7 @@
 '      ti \w'\\[dcap]'u
 .    \}
 .  \}
-.  nop \\mP\\$2
+.  nop \\m[]\\$2
 ..
 .\"
 .\" now set up TS, TE, EQ, EN default macros