* man/groff_tmac.man: Updated and extended.

1 files changed, 973 insertions, 279 deletions

diff --git a/man/groff_tmac.man b/man/groff_tmac.man
index db2a0bb7..bb8288d5 100644
--- a/man/groff_tmac.man
+++ b/man/groff_tmac.man
@@ -1,10 +1,27 @@
+.
+.TH GROFF_TMAC @MAN5EXT@ "@MDATE@" "Groff Version @VERSION@"
+.SH NAME
+groff_tmac \- macro files in the roff typesetting system
+.SH DESCRIPTION
+.\" The .SH was moved to this place to make `apropos' happy.
+.
+.
+.\" --------------------------------------------------------------------
+.\" Legalize
+.\" --------------------------------------------------------------------
+.
 .ig
 groff_tmac.5
 
+File position: <groff-source>/man/groff_tmac.man
+
+Last update: 25 June 2002
+
 This file is part of groff, the GNU roff type-setting system.
 
 Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
-written by Bernd Warken <bwarken@mayn.de>
+written by Bernd Warken <bwarken@mayn.de> and Werner Lemberg
+<wl@gnu.org>
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.1 or
@@ -20,6 +37,8 @@ FDL in the main directory of the groff source package.
 .\" Setup
 .\" --------------------------------------------------------------------
 .
+.mso www.tmac
+.
 .if n \{\
 .  mso tty-char.tmac
 .  ftr CR R
@@ -27,423 +46,1098 @@ FDL in the main directory of the groff source package.
 .  ftr CB B
 .\}
 .
-.\" text lines in macro definitions or bracketed sections \{...\}
-.de text
-.  if 1 \&\\$*\&
-..
+.ds Ellipsis \.\|.\|.\&\"
+.
+.\" Global static variables for inter-macro communication
+.rr @+Example_font
+.
+.\" --------------------------------------------------------------------
+.\" setup for the macro definitions below
+.\"
+.\" naming:  namespace:cathegory_macro.variable_name  (experimental)
+.
+.\" --------------------------------------------------------------------
+.\" configuration of prompt for `.Shell_cmd'* macros
+.ds groffer:Shell_cmd.prompt_text sh#\"    prompt for shell commands
+.ds groffer:Shell_cmd+.prompt_text >\"     prompt on continuation lines
+.ds groffer:Shell_cmd_base.prompt_font I\" font for prompts
 .
+.\" automatically determine setup from the configuration above
+.als @f groffer:Shell_cmd_base.prompt_font\"
+.als @t groffer:Shell_cmd.prompt_text\"
+.als @t+ groffer:Shell_cmd+.prompt_text\"
+.ds groffer:Shell_cmd.prompt \f[\*[@f]]\*[@t]\f[]\"            needed
+.ds groffer:Shell_cmd+.prompt \f[\*[@f]]\*[@t+]\f[]\"          needed
+.nr @w \w'\*[groffer:Shell_cmd.prompt]'\"
+.nr @w+ \w'\*[groffer:Shell_cmd+.prompt]'\"
+.ft \*[@f]
+.\" Full prompt width is maximum of texts plus 1m
+.nr groffer:Shell_cmd_base.prompt_width (\n[@w]>?\n[@w+]+1m)\" needed
+.ft
+.rm @f
+.rm @f+
+.rm @t
+.rm @t+
+.rr @w
+.rr @w+
+.
+.\"--------------------------------------------------------------------
+.\" Ignore all arguments like a comment, even after a .eo call.
+.de c
+..
+.c --------------------------------------------------------------------
 .de BIR
 .  ie (\\n[.$] < 3) \
 .    BI \\$@
 .  el \{\
-.    ds @tmp@ \fB\\$1\fP\fI\\$2\fP
+.    ds @tmp@ \fB\\$1\f[]\fI\\$2\f[]
 .    shift 2
-.    text \\*[@tmp@]\fR\\$*\fP
+.    Text \\*[@tmp@]\fR\\$*\f[]
 .    rm @tmp@
 .  \}
 ..
+.c --------------------------------------------------------------------
+.de CB
+.  nr @+f \\n[.f]
+.  ft CB
+.  Text \\$@
+.  ft \\n[@+f]
+.  rr @+f
+..
+.c --------------------------------------------------------------------
+.de CI
+.  nr @+f \\n[.f]
+.  ft CI
+.  Text \\$@
+.  ft \\n[@+f]
+.  rr @+f
+..
+.c --------------------------------------------------------------------
+.de CR
+.  nr @+f \\n[.f]
+.  ft CR
+.  Text \\$@
+.  ft \\n[@+f]
+.  rr @+f
+..
+.c --------------------------------------------------------------------
+.c .Env_var  (<env_var_name> [<punct>])
+.c
+.c Display an environment variable, with optional punctuation.
+.c
+.de Env_var
+.  nh
+.  SM
+.  Text \f[CB]\\$1\f[]\\$2
+.  hy
+..
+.c --------------------------------------------------------------------
+.c .Error  (<text>...)
+.c
+.c Print error message to terminal and abort.
+.c
+.de Error
+.  tm \\$*
+.  ab
+..
+.c --------------------------------------------------------------------
+.de Example
+.  if r@+Example_font \
+.    Error previous .Example was not terminated by a ./Example
+.  nr @+Example_font \\n[.f]
+.  nh
+.  nf
+.  RS
+.  ft CR
+..
+.c --------------------------------------------------------------------
+.de /Example
+.  if !r@+Example_font \
+.    Error no previous call to .Example
+.  ft \\n[@+Example_font]
+.  RE
+.  fi
+.  hy
+.  rr @+Example_font
+..
 .
+.c --------------------------------------------------------------------
+.c .Shell_cmd  (<CR> [<CI>] ...)
+.c
+.c A shell command line; display args alternating in fonts CR and CI.
+.c
+.c Examples:
+.c   .Shell_cmd "groffer --dpi 100 file"
+.c     result: `sh#  groffer --dpi 100 file'
+.c             with 'sh#' in font I, the rest in CR
+.c
+.c   .Shell_cmd groffer\~--dpi\~100\~file
+.c     result: the same as above
+.c
+.c   .Shell_cmd "groffer --dpi=" value " file"
+.c     result: sh#  groffer --dpi=value file
+.c             with `groffer --dpi=' and `file' in CR; `value' in CI
+.c
+.c   .Shell_cmd groffer\~--dpi= value \~file
+.c     result: the same as the previous example
+.c
+.de Shell_cmd
+.  groffer:Shell_cmd_base "\*[groffer:Shell_cmd.prompt]" \\$@
+..
+.c --------------------------------------------------------------------
+.c .Shell_cmd+  (<CR> [<CI>] ...)
+.c
+.c A continuation line for .Shell_cmd.
+.c
+.de Shell_cmd+
+.  groffer:Shell_cmd_base "\*[groffer:Shell_cmd+.prompt]" \\$@
+..
+.c --------------------------------------------------------------------
+.c .Shell_cmd_base  (<prompt> [<CR> [<CI>] ...])
+.c
+.c A shell command line; display args alternating in fonts CR and CI.
+.c Internal, do not use directly.
+.c
+.c Globals: read-only register @.Shell_cmd_width
+.c
+.de groffer:Shell_cmd_base
+.  if (\\n[.$] <= 0) \
+.    return
+.  nr @+font \\n[.f]\"
+.  ds @prompt \\$1\"
+.  ft CR
+.  c gap between prompt and command
+.  nr @+gap \\n[groffer:Shell_cmd_base.prompt_width]-\\w'\\*[@prompt]'\"
+.  ds @res \\*[@prompt]\h'\\n[@+gap]u'\"
+.  shift
+.  ds @cf CR\"
+.  while (\\n[.$] > 0) \{\
+.    as @res \\f[\\*[@cf]]\\$1\"
+.    shift
+.    ie '\\*[@cf]'CR' \
+.      ds @cf I\"
+.    el \
+.      ds @cf CR\"
+.  \}
+.  br
+.  ad l
+.  nh
+.  nf
+.  Text \\*[@res]\"
+.  fi
+.  hy
+.  ad
+.  br
+.  ft \\n[@+font]
+.  rr @+font
+.  rr @+gap
+.  rm @cf
+.  rm @res
+..
+.c --------------------------------------------------------------------
+.c .Text  (<text>...)
+.c
+.c Treat the arguments as text, no matter how they look.
+.c
+.de Text
+.  if (\\n[.$] == 0) \
+.    return
+.  nop \)\\$*\)
+..
+.c --------------------------------------------------------------------
+.c .Topic  ([<indent>])
+.c
+.c A bulleted paragraph
+.c
+.de Topic
+.  ie (\\n[.$] = 0) \
+.    .ds @indent 2m\"
+.  el \
+.    .ds @indent \\$1\"
+.  TP \\*[@indent]
+.  Text \[bu]
+.  rm @indent
+..
+.c --------------------------------------------------------------------
+.c .TP+  ()
+.c
+.c Continuation line for .TP header.
+.c
+.de TP+
+.  br
+.  ns
+.  TP \\$1
+..
+.c --------------------------------------------------------------------
 .de 'char
-.  ds @tmp@ `\f(CB\\$1\fP'
+.  ds @tmp@ `\f(CR\\$1\f[]'
 .  shift
-.  text \\*[@tmp@]\\$*
+.  Text \\*[@tmp@]\\$*
 .  rm @tmp@
 ..
-.
+.c --------------------------------------------------------------------
 .de option
-.  ds @tmp@ \f(CB\\$1\fP
+.  ds @tmp@ \f(CB\\$1\f[]
 .  shift 1
-.  text \\*[@tmp@]\\$*
+.  Text \\*[@tmp@]\\$*
 .  rm @tmp@
 ..
-.
-.als shellcommand option
-.
+.c --------------------------------------------------------------------
 .de argument
-.  ds @tmp@ \f(CI\\$1\fP
+.  ds @tmp@ \f(CI\\$1\f[]
 .  shift 1
-.  text \\*[@tmp@]\\$*
+.  Text \\*[@tmp@]\\$*
 .  rm @tmp@
 ..
-.
+.c --------------------------------------------------------------------
 .de request
-.  ds @tmp@ \f(CB\\$1\fP
+.  ds @tmp@ \f(CB\\$1\f[]
 .  shift 1
-.  text \\*[@tmp@]\\$*
+.  Text .\\*[@tmp@]\\$*
+.  rm @tmp@
+..
+.c --------------------------------------------------------------------
+.de escape
+.  ds @tmp@ \f[CB]\\$1\f[]
+.  shift 1
+.  Text \[rs]\\*[@tmp@]\\$*
 .  rm @tmp@
 ..
-.
-.\" --------------------------------------------------------------------
-.\" Title
-.\" --------------------------------------------------------------------
-.TH GROFF_TMAC @MAN5EXT@ "@MDATE@" "Groff Version @VERSION@"
-.SH NAME
-groff_tmac \- macro files in the roff typesetting system
 .\" --------------------------------------------------------------------
-.SH DESCRIPTION
+.\" SH DESCRIPTION
 .\" --------------------------------------------------------------------
+.
 The
 .BR roff (@MAN7EXT@)
 type-setting system provides a set of macro packages suitable for
-special kinds of documents.  Each macro package stores its macros and
-definitions in a file called the package's
+special kinds of documents.
+.
+Each macro package stores its macros and definitions in a file called
+the package's
 .BR "tmac file" .
 The name is deduced from
-.RB ` T roff
-.BR MAC ros'.
-.LP
+.RB ` T\c
+.IB roff MAC\c
+.IR ros '.
+.
+.P
 The tmac files are normal roff source documents, except that they
-usually contain only definitions and setup commands, but no text.  All
-tmac files are kept in a single or a small number of directories, the
+usually contain only definitions and setup commands, but no text.
+.
+All tmac files are kept in a single or a small number of directories,
+the
 .B tmac
 directories.
+.
+.
+.\" --------------------------------------------------------------------
+.SH "GROFF MACRO PACKAGES"
+.\" --------------------------------------------------------------------
+.
+.I groff
+provides all classical macro packages, some more full packages, and
+some secondary packages for special purposes.
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Man\~Pages"
+.\" --------------------------------------------------------------------
+.
+.TP
+.B man
+This is the classical macro package for UNIX manual pages
+(man\~pages); it is quite handy and easy to use; see
+.BR groff_man (@MAN7EXT@).
+.
+.TP
+.B doc
+.TP+
+.B mdoc
+An alternative macro package for man\~pages mainly used in BSD systems; it
+provides many new features, but is not the standard for man\~pages;
+see
+.BR groff_mdoc (@MAN7EXT@).
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Full Packages"
+.\" --------------------------------------------------------------------
+.
+The packages in this section are provide a complete set of macros for
+writing documents of any kind, up to whole books.
+.
+They are similar in functionality; it is a matter of taste which one
+to use.
+.
+.
+.TP
+.B me
+The classical
+.I me
+macro package;
+see
+.BR groff_me (@MAN7EXT@).
+.
+.
+.TP
+.B mm
+The semi-classical
+.I mm
+macro package;
+see
+.BR groff_mm (@MAN7EXT@).
+.
+.
+.TP
+.B mom
+The new
+.I mom
+macro package, only available in groff.
+.
+As this is not based on other packages, it can be freely designed.
+.
+So it is expected to become quite a nice, modern macro package.
+.
+See
+.BR groff_mom (@MAN7EXT@).
+.
+.
+.TP
+.B ms
+The classical
+.I ms
+macro package;
+see
+.BR groff_ms (@MAN7EXT@).
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Special Packages"
+.\" --------------------------------------------------------------------
+.
+The macro packages in this section are not intended for stand-alone
+usage, but can be used to add special functionality to any other
+macro package or to plain groff.
+.
+.
+.TP
+.B tty-char
+Overrides the definition of standard troff characters and some groff
+characters for tty devices.
+.
+The optical appearance is intentionally inferior compared to that of
+normal tty formatting to allow processing with critical equipment.
+.
+.
+.TP
+.B www
+Additions of elements known from the html format, as being used in the
+internet (World Wide Web) pages; this includes URL links and mail
+addresses; see
+.BR groff_www (@MAN7EXT@).
+.
+.
 .\" --------------------------------------------------------------------
 .SH NAMING
 .\" --------------------------------------------------------------------
-In classical roff systems, there was a funny naming scheme.
-If the name of a macro package started with
-.'char m
-this letter was omitted, e.g., the macro package for the man pages
-.I man
-was called
+.
+In classical roff systems, there was a funny naming scheme for macro
+packages, due to a simplistic design in option parsing.
+.
+Macro packages were always included by option
+.option -m;
+when this option was directly followed by its argument without an
+intervening space, this looked like a long option preceded by a single
+minus \[em] a sensation in the computer stone age.
+.
+To make this optically working for macro package names, all classical
+macro packages choose a name that started with the letter
+.'char m ,
+which was omitted in the naming of the macro file.
+.
+.
+.P
+For example, the macro package for the man pages was called
+.IR man ,
+while its macro file
+.IR tmac.an .
+So it could be activated by the argument
 .I an
-and its macro file
-.I tmac.an
-(note that in recent versions of groff this file is called
-.I an.tmac
-instead).
-.LP
-By a similar reasoning, macro packages that did not start with an
+to option
+.option -m ,
+or
+.option -man
+for short.
+.
+.
+.P
+For similar reasons, macro packages that did not start with an
 .'char m
-were often referred to by adding an
-.'char m ,
-e.g., the package corresponding to
+had a leading
+.'char m
+added in the documentation and in talking; for example, the package
+corresponding to
 .I tmac.doc
 was called
 .I mdoc
-because the command-line for activating it reads
-.RS
-.LP
-.BIR "troff\ \-m" doc .
-.RE
-.LP
-Actual versions of
+in the documentation, although a more suitable name would be
+.IR doc .
+For, when omitting the space between the option and its argument, the
+command line option for activating this package reads
+.option "-mdoc" .
+.
+.
+.P
+To cope with all situations, actual versions of
 .BR groff (@MAN1EXT@)
-provide both naming schemes for the inflicted macro packages, with and
-without the leading
-.'char m .
+are smart about both naming schemes by providing two macro files
+for the inflicted macro packages; one with a leading
+.'char m ,
+the other one without it.
+.
 So in
 .IR groff ,
 the
 .I man
-macro package may be specified as
+macro package may be specified as on of the following four methods:
+.
 .RS
-.LP
-.BIR "groff\ \-m\ " man ,
-.br
-.BIR "groff\ \-m" an ,
-.br
-.BIR "groff\ \-m" man , or
-.br
-.BIR "groff\ \-m " an .
+.P
+.Shell_cmd "groff\~\-m\~man"
+.Shell_cmd "groff\~\-man"
+.Shell_cmd "groff\~\-mman"
+.Shell_cmd "groff\~\-m\~an"
 .RE
-.LP
+.
+.P
+Recent packages that do not start with
+.'char m
+do not use an additional
+.'char m
+in the documentation.
+.
+For example, the
+.I www
+macro package may be specified only as one of the two methods:
+.
+.P
+.RS
+.Shell_cmd "groff\~\-m\~www"
+.Shell_cmd "groff\~\-mwww"
+.RE
+.
+.P
+Obviously, variants like
+.CR -mmwww
+would not make much sense.
+.
+.
+.P
+A second strange feature of classical troff was to name macro files
+according to
+.BIR tmac. name .
+In modern operating systems, the type of a file is specified as
+postfix, the extension.
+.
+Again, groff copes with this situation by searching both
+.IB anything .tmac
+and
+.BI tmac. anything
+if only
+.I anything
+is specified.
+.
+.
+.P
 The easiest way to find out which macro packages are available on a
-system is to check the contents of the
+system is to check the man\~page
+.BR groff (@MAN1EXT@),
+or the contents of the
 .I tmac
 directories.
-For example, a file called
-.BI tmac. anything
-or
-.IB anything .tmac
-determines a macro package named
-.IR anything .
-.LP
+.
+.
+.P
 In
 .IR groff ,
-most macro packages are described in man pages called
-.BR groff_<name> (@MAN7EXT@),
+most macro packages are described in\~man pages called
+.BR groff_\f[I]name\f[] (@MAN7EXT@),
 with a leading
 .'char m
 for the classical packages.
+.
+.
 .\" --------------------------------------------------------------------
 .SH INCLUSION
 .\" --------------------------------------------------------------------
-There are several ways to use a macro package in documents.  At
-run-time, the groff option
-.option \-m \ \c
+.
+There are several ways to use a macro package in a document.
+.
+The classical way is to specify the troff/groff option
+.option \-m
 .argument name
-makes the definitions in the macro file
-.IB name .tmac
-available as described in the section
-.BR NAMING .
-If this file isn't found,
-.BI tmac. name
-will be searched.
-.LP
-It is also possible to include the macro file into the document by using
-the groff requests
-.request .so
-or
-.request .mso .
-For
-.request .so
-the full filename of the macro file must be specified \(em including the
-directory where it is kept.
-If the macro file is stored in one of the tmac directories it is more
-convenient to use
-.request .mso
-instead because it searches the tmac path for the filename.
-Additionally, if the file name to be included has the form
+at run-time; this makes the contents of the macro package
+.I name
+available.
+.
+In groff, the file
 .IB name .tmac
-and it isn't found,
-.request .mso
-will try to open
+is searched within the tmac path; if not found,
 .BI tmac. name
-instead and vice versa.
-.LP
+will be searched for instead.
+.
+.
+.P
+Alternatively, it is also possible to include a macro file by adding
+the request
+.request so
+.I filename
+into the document; the argument must be the full file name of an
+existing file, possibly with the directory where it is kept.
+.
+In groff, this was improved by the similar request
+.request mso
+.IR package ,
+which added searching in the tmac path, just like option
+.option -m
+does.
+.
+.
+.P
 Note that in order to resolve the
-.request .so
+.request so
 and
-.request .mso
-requests the roff preprocessor
-.shellcommand soelim
-must be called if the files to be included needs preprocessing.
-This can be done either directly by a pipeline on the command line or by
-using the
-.option \-s
-option of
-.shellcommand groff .
-.LP
-You can also supply the letter
-.'char s
-in the preprocessor word as described in section
-.BR CONVENTION .
-.LP
+.request mso
+requests, the roff preprocessor
+.BR soelim (@MAN1EXT@)
+must be called if the files to be included need preprocessing.
+.
+This can be done either directly by a pipeline on the command line or
+by using the troff/groff option
+.option \-s .
+.
+.I man
+calls soelim automatically.
+.
+.
+.P
 For example, suppose a macro file is stored as
 .I @MACRODIR@/macros.tmac
 and is used in some document called
 .IR docu.roff .
-.LP
+.
+.P
 At run-time, the formatter call for this is
 .RS
-.LP
-.ft CR
-.shellcommand "groff\ \-m"
-.argument macros
-.argument docu.roff
-.ft P
+.P
+.Shell_cmd "groff\~\-m\~" "macrofile\~document.roff"
 .RE
-.LP
+.
+.P
 To include the macro file directly in the document either
 .RS
-.ft CR
-\&\.mso macros.tmac
-.ft P
+.CR .mso macrofile.tmac
 .RE
 is used or
 .RS
-.ft CR
-\&\.so @MACRODIR@/macros.tmac
-.ft P
+.CR .so @MACRODIR@/macros.tmac
 .RE
-.LP
+.
+.P
 In both cases, the formatter is called with
-.ft CR
 .RS
-groff\ \-s docu.roff
+.Shell_cmd "troff\~\-s\~" docu.roff
 .RE
-.ft P
 .
+.
+.P
+If you want to write your own groff macro file, call it
+.IB whatever .tmac
+and put it in some directory of the tmac path, cf.\& section
+.BR FILES .
+Then documents can include it with the
+.request mso
+request or the option
+.option -m .
+.
+.
+.ig
 .\" --------------------------------------------------------------------
 .SH CONVENTION
 .\" --------------------------------------------------------------------
-.LP
+.
 There is a convention that is supported by many modern roff
-type-setters: the
-.B preprocessor word
+type-setters and
+.BR man (1)
+programs, the
+.I preprocessor word
 described in the following.
-.LP
+.
+.P
 If the first line in a document is a comment, the first word (after the
 comment characters and a blank) constitutes the
 .B preprocessor
 .BR word .
 That means that the letters of this word are interpreted as
 abbreviations for those preprocessor commands that should be run
-when formatting the document.  Mostly, only the letters corresponding to
-the options for the preprocessors are recognized,
-.'char e ,
-.'char G ,
-.'char g ,
+when formatting the document.
+.
+Mostly, only the letters corresponding to the options for the
+preprocessors are recognized,
+.'char e
+(for
+.BR eqn ),
+.\" 'char G ,
+.\" 'char g ,
 .'char p ,
-.'char R ,
-.'char s , and
+(for
+.BR pic ),
+.'char R
+(for
+.BR refer ),
+.'char s
+(for
+.BR soelim ),
+and
 .'char t
+(for
+.BR tbl ).
 (see
 .BR roff (@MAN7EXT@)).
-.LP
+.
+.
+.P
 Besides being a good reminder for the user, some formatters (like the
 .BR man (1)
 program) are even able to automatically start the preprocessors
 specified in the preprocessor word, but do not bet on this.
+.
+.
+.P
+The
+.I man
+program handles some preprocessors automatically, such that in
+man\~pages only the following characters should be used:
+.'char e ,
+.'char p ,
+and
+.'char t .
+.
+.
+..
 .\" --------------------------------------------------------------------
-.SH "WRITING A MACRO FILE"
-.\" --------------------------------------------------------------------
-Writing a groff macro file is easy.  Design a set of macros, strings,
-registers, etc.  Store them in a single file.  Documents that use the
-macros include this macro file with the
-.request .so
-request as described in the
-.B INCLUSION
-section.
-.LP
-To use the tmac functionality, call the macro file
-.IB whatever .tmac
-(or
-.BI tmac. whatever\c
-) and put it in some directory of the tmac path, cf. section
-.BR FILES .
-Then documents can include it with the
-.request .mso
-request or the
-.shellcommand "groff\ \-m"
-option as described in the
-.B INCLUSION
-section.
-.LP
-If your macros might be of general usage contact the groff maintainers
-to have them included in the groff
-.I contrib
-source directory.
-.LP
-Some general guidelines might be helpful in writing macros.
-.IP \(bu 2m
-Double all functional backslashes,
-.'char \e
-->
-.'char \e\e .
-.IP \(bu 2m
-All printable backslashes must be written as
-.'char \ee .
-.IP \(bu 2m
-Escape all dots,
-.'char .
-->
-.'char \e. .
-.IP \(bu 2m
-Make ample use of the non-printable character
-.'char \e&
-in text parts, esp. before
-.'char \e
-and at the beginning of a line, but not before a delayed command.
-.IP \(bu 2m
-Use the character
-.'char @
-in temporary variable names.
-.IP \(bu 2m
-Test your macros for text and graphical devices, e.g.,
-.I latin1
+.SH "WRITING MACROS"
+.\" --------------------------------------------------------------------
+.
+A
+.BR roff (@MAN7EXT@)
+document is a text file that is enriched by predefined formatting
+constructs, such as requests, escape sequences, strings, numeric
+registers, and macros from a macro package.
+.
+These elements are described in
+.BR roff (@MAN7EXT@).
+.
+.
+.P
+To give a document a personal style, it is most useful to extend the
+existing elements by defining some macros for repeating tasks; the best
+place for this is near the beginning of the document or in a separate
+file.
+.
+.
+.P
+Macros without arguments are just like strings.
+.
+But the full power of macros reveals when arguments are passed with a
+macro call.
+.
+Within the macro definition, the arguments are available as the escape
+sequences
+.BR $1 ,
+\*[Ellsipsis],
+.BR $9 ,
+.BR $[ \*[Ellsipsis] ] ,
+.BR $* ,
+and
+.BR $@ ,
+the name under which the macro was called is in
+.BR $0 ,
+and the number of arguments is in register
+.BR \n[.$] ;
+see
+.BR groff (@MAN7EXT@).
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Copy-in Mode"
+.\" --------------------------------------------------------------------
+.
+The phase when groff reads a macro is called
+.I "copy-in mode"
+in roff-talk.
+.
+This is comparable to the C\~preprocessing phase during the development
+of a program written in the C\~language.
+.
+.
+.P
+In this phase, groff interprets all backslashes; that means that all
+escape sequences in the macro body are interpreted and replaced by
+their value.
+.
+For constant expression, this is wanted, but strings and registers
+that might change between calls of the macro must be protected from
+being evaluated.
+.
+This is most easily done by doubling the backslash that introduces the
+escape sequence.
+.
+This doubling is most important for the positional parameters.
+.
+For example, to print information on the arguments that were passed to
+the macro to the terminal, define a macro named
+. print_args ,
+say.
+.
+.
+.P
+.ds @1 \[rs]f[I]\[rs]\[rs]$0\[rs]f[]\"
+.ds @2 arguments:\"
+.Example
+.Text .ds midpart was called with
+.Text .de print_args
+.Text .\~\~tm\~\*[@1]\~\[rs]\[rs]*[midpart]\~\[rs]\[rs]n[.$]\~\*[@2]
+.Text .\~\~tm\~\[rs]\[rs]$*
+.Text ..
+./Example
+.rm @1
+.rm @2
+.
+.
+.P
+When calling this macro by
+.P
+.Example
+.Text .print_args arg1 arg2
+./Example
+.P
+the following text is printed to the terminal:
+.Example
+\f[CI]print_args\f[] was called with the following 2 arguments:
+arg1 arg2
+./Example
+.
+.
+.P
+Let's analyze each backslash in the macro definition.
+.
+As the positional parameters and the number of arguments will change
+with each call of the macro their leading backslash must be doubled,
+which results in
+.I \[rs]\[rs]$*
 and
-.IR ps .
+.IR \[rs]\[rs][.$] .
+The same applies to the macro name because it could be called with an
+alias name, so
+.IR \[rs]\[rs]$0 .
+.
+.
+.P
+On the other hand,
+.I midpart
+is a constant string, it will not change, so no doubling for
+.IR \[rs]*[midpart] .
+The
+.I \[rs]f
+escape sequences are predefined groff elements for setting the font
+within the text.
+.
+Of course, this behavior will not change, so no doubling with
+.I \[rs]f[I]
+and
+.IR \[rs]f[] .
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Draft Mode"
+.\" --------------------------------------------------------------------
+.
+Writing groff macros is easy when the escaping mechanism is temporarily
+disabled.
+.
+In groff, this is done by enclosing the macro definition(s) into a
+pair of
+.B .eo
+and
+.B .ec
+requests.
+.
+Then the body in the macro definition is just like a normal part of
+the document \[em] text enhanced by calls of requests, macros,
+strings, registers, etc.
+.
+For example, the code above can be written in a simpler way by
+.
+.
+.P
+.ds @1 \[rs]f[I]\[rs]$0\[rs]f[]\"
+.ds @2 arguments:\"
+.Example
+.Text .eo
+.Text .ds midpart was called with
+.Text .de print_args
+.Text .\~\~tm\~\*[@1]\~\[rs]*[midpart]\~\[rs]n[.$]\~\*[@2]
+.Text .\~\~tm\~\[rs]$*
+.Text ..
+.Text .ec
+./Example
+.rm @1
+.rm @2
+.
+.
+.P
+Unfortunately, draft mode cannot be used universally.
+.
+Although it is good enough for defining normal macros, draft mode
+will fail with advanced applications, such as indirectly defined
+strings, registers, etc.
+.
+An optimal way is to define and test all macros in draft mode and then
+do the backslash doubling as a final step; do not forget to remove the
+.I .eo
+request.
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Tips for Macro Definitions"
+.\" --------------------------------------------------------------------
+.
+.Topic
+Start every line with a dot, for example, by using the groff request
+.B .nop
+for text lines, or write your own macro that handles also text lines
+with a leading dot.
+.
+.IP
+.Example
+.Text .de Text
+.Text .\~\~if (\[rs]\[rs]n[.$] == 0)\~\[rs]
+.Text .\~\~\~\~return
+.Text .\~nop\~\[rs])\[rs]\[rs]$*[rs]\)
+.Text ..
+./Example
+.
+.Topic
+Write a comment macro that works both for copy-in and draft mode; for
+as escaping is off in draft mode, trouble might occur when normal
+comments are used.
+.
+For example, the following macro just ignores its arguments, so it
+acts like a comment line:
+.
+.IP
+.Example
+.Text .de\~c
+.Text ..
+.Text .c\~This\~is\~like\~a\~comment\~line.
+./Example
+.
+.Topic
+In long macro definitions, make ample use of comment lines or empty
+lines for a better structuring.
+.
+.Topic
+To increase readability, use groff's indentation facility for requests
+and macro calls (arbitrary whitespace after the leading dot).
+.
+.
+.\" --------------------------------------------------------------------
+.SS "Diversions"
+.\" --------------------------------------------------------------------
+.
+Diversions can be used to realize quite advanced programming
+constructs.
+.
+They are comparable to pointers to large data structures in the
+C\~programming language, but their usage is quite different.
+.
+.
+.P
+In their simplest form, diversions are multi-line strings, but
+they get their power when diversions are used dynamically within macros.
+.
+The information stored in a diversion can be retrieved by calling the
+diversion just like a macro.
+.
+.
+.P
+Most of the problems arising with diversions can be avoided if you are
+conscious about the fact that diversions always deal with complete
+lines.
+.
+If diversions are used if the line buffer has not been flashed,
+strange results are produced; not knowing this, many people get
+desperate about diversions.
+.
+To ensure that a diversion works, line breaks should be added at the
+right places.
+.
+To be on the secure side, enclose everything that has to do with
+diversions into a pair of line breaks; for example, by amply using
+.B .br
+requests.
+.
+This rule should be applied to diversion definition, both inside and
+outside, and to all calls of diversions.
+.
+This is a bit of overkill, but it works nicely.
+.
+.
+.P
+[If you really need diversions which should ignore the current partial
+line, use environments to save the current partial line and/\:or use the
+.B .box
+request.]
+.
+.
+.P
+The most powerful feature using diversions is to start a diversion
+within a macro definition and end it within another macro.
+.
+Then everything between each call of this macro pair is stored within
+the diversion and can be manipulated from within the macros.
+.
+.
 .\" --------------------------------------------------------------------
 .SH FILES
 .\" --------------------------------------------------------------------
+.
 All macro names must be named
 .IB name .tmac
-or
+to fully use the tmac mechanism.
+.
 .BI tmac. name
-to use the tmac mechanism.
-.LP
+as with	classical packages is possible as well, but deprecated.
+.
+.
+.P
 The macro files are kept in the
-.B tmac
-.BR directories ,
-all of which constitute the
-.B tmac
-.BR path.
-.LP
-The elements of the search path for macro files are (in that order):
-.IP \(bu 4
-the directories specified with troff's resp. groff's
+.IR "tmac directories" ;
+a colon separated list of these constitutes the
+.IR "tmac path" .
+.
+.
+.P
+The search sequence for macro files is (in that order):
+.
+.Topic
+the directories specified with troff/groff's
 .B \-M
 command line option
-.IP \(bu 4
+.
+.Topic
 the directories given in the
-.B GROFF_TMAC_PATH
+.Env_var $GROFF_TMAC_PATH
 environment variable
-.IP \(bu 4
-the current directory (only if in unsafe mode using the
+.
+.Topic
+the current directory (only if in unsafe mode, which is enabled by the
 .B \-U
 command line switch)
-.IP \(bu 4
+.
+.Topic
 the home directory
-.IP \(bu 4
-a platform-specific directory, a site-specific (platform-independent)
-directory, and the main tmac directory:
-.IP "" 6
-@SYSTEMMACRODIR@
-.br
-@LOCALMACRODIR@
-.br
-@MACRODIR@
+.
+.Topic
+a platform-specific directory, being
+.B @SYSTEMMACRODIR@
+in this installation
+.
+.Topic
+a site-specific (platform-independent) directory, being
+.B @LOCALMACRODIR@
+in this installation
+.
+.Topic
+the main tmac directory, being
+.B @MACRODIR@
+in this installation
+.
+.
 .\" --------------------------------------------------------------------
 .SH ENVIRONMENT
 .\" --------------------------------------------------------------------
+.
 .TP
-.B GROFF_TMAC_PATH
+.Env_var $GROFF_TMAC_PATH
 A colon separated list of additional tmac directories in which to search
 for macro files.
+.
 See the previous section for a detailed description.
-.\" --------------------------------------------------------------------
-.SH BUGS
-.\" --------------------------------------------------------------------
-The groff documentation is in evolution at the moment.  It is possible
-that small inconsistencies between different documents exist
-temporarily.
+.
+.
 .\" --------------------------------------------------------------------
 .SH AUTHOR
 .\" --------------------------------------------------------------------
-This document is part of groff, the GNU roff distribution.  It was
-written by Bernd Warken <bwarken@mayn.de>.
-.LP
-It is distributed under the terms of the FDL (GNU Free Documentation
-License) version 1.1 or later.  You should have received a copy of the
-FDL on your system, it is also available on-line under
-.RS
-.LP
-.IR <http://www.gnu.org/copyleft/fdl.html> .
-.RE
+.
+Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
+.
+.P
+This document is distributed under the terms of the FDL (GNU Free
+Documentation License) version 1.1 or later.
+.
+You should have received a copy of the FDL on your system, it is also
+available on-line at the
+.URL http://\:www.gnu.org/\:copyleft/\:fdl.html "GNU copyleft site" .
+.
+.P
+This document is part of
+.IR groff ,
+the GNU roff distribution.
+.
+It was written by
+.MTO bwarken@mayn.de "Bernd Warken" ;
+it is maintained by
+.MTO wl@gnu.org "Werner Lemberg" .
+.
+.
 .\" --------------------------------------------------------------------
 .SH "SEE ALSO"
 .\" --------------------------------------------------------------------
-The authoritative source of information for all details of the groff
-system is the groff
+.
+A complete reference for all parts of the groff system is found in the groff
 .BR info (1)
 file.
-.LP
-For a groff overview, see
-.BR roff (@MAN7EXT@)
-and the file
-.I README
-in the groff source package.
-.LP
-The groff tmac macro packages are
+.
+.TP
+.BR groff (@MAN1EXT@)
+an overview of the groff system.
+.
+.TP
 .BR groff_man (@MAN7EXT@),
-.BR groff_www (@MAN7EXT@),
+.TP+
 .BR groff_mdoc (@MAN7EXT@),
+.TP+
 .BR groff_me (@MAN7EXT@),
+.TP+
 .BR groff_mm (@MAN7EXT@),
-.BR groff_mmroff (@MAN7EXT@),
-and
-.BR groff_ms (@MAN7EXT@).
-.LP
-The groff language is described in
+.TP+
+.BR groff_mom (@MAN7EXT@),
+.TP+
+.BR groff_ms (@MAN7EXT@),
+.TP+
+.BR groff_www (@MAN7EXT@).
+the groff tmac macro packages.
+.
+.TP
 .BR groff (@MAN7EXT@)
-and the formatters in
-.BR groff (@MAN1EXT@),
-.BR troff (@MAN1EXT@).
-.LP
-The Filesystem Hierarchy Standard (FHS) is available at
-.BR http://www.pathname.com/fhs/ .
+the groff language.
+.
+.
+.P
+The Filesystem Hierarchy Standard is available at the
+.URL http://\:www.pathname.com/\:fhs/ "FHS web site" .
 .
 .\" Local Variables:
 .\" mode: nroff