This is groff.info, produced by makeinfo version 4.0 from groff.texi.

INFO-DIR-SECTION Miscellaneous
START-INFO-DIR-ENTRY
* Groff: (groff).   The GNU troff document formatting system.
END-INFO-DIR-ENTRY

   This Info file documents GNU troff version 1.12.

   Published by the Free Software Foundation 59 Temple Place, Suite 330
Boston, MA  02111-1307  USA

   Copyright (C) 1994, 1999 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the section entitled "GNU General Public License" is included
exactly as in the original, and provided that the entire resulting
derived work is distributed under the terms of a permission notice
identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the section entitled "GNU General Public License"
may be included in a translation approved by the Free Software
Foundation instead of in the original English.


File: groff.info,  Node: Top,  Next: Copying,  Prev: (dir),  Up: (dir)

   This Info file documents groff version 1.13, the GNU implementation
of the troff typesetting system.

   This is an in-progress document; contributions, comments, or
contributions are welcome.  Send them to bug-groff@gnu.org.

* Menu:

* Copying::
* Introduction::
* Invoking groff::
* Tutorial for Macro Users::
* Programming Tutorial::
* File formats::
* Request Index::
* Register Index::
* Program Index::
* Concept Index::


File: groff.info,  Node: Copying,  Next: Introduction,  Prev: Top,  Up: Top

GNU GENERAL PUBLIC LICENSE
**************************

                         Version 2, June 1991

     Copyright (C) 1989, 1991 Free Software Foundation, Inc.
     59 Temple Place, Suite 330, Boston, MA 02111, USA
     
     Everyone is permitted to copy and distribute verbatim copies of this
     license document, but changing it is not allowed.

Preamble
========

   The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software - to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software Foundation's
software and to any other program whose authors commit to using it.
(Some other Free Software Foundation software is covered by the GNU
Library General Public License instead.)  You can apply it to your
programs, too.

   When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it in
new free programs; and that you know you can do these things.

   To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

   For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

   We protect your rights with two steps: (1) copyright the software,
and (2) offer you this license which gives you legal permission to
copy, distribute and/or modify the software.

   Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

   Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

   The precise terms and conditions for copying, distribution and
modification follow.

    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains a
     notice placed by the copyright holder saying it may be distributed
     under the terms of this General Public License.  The "Program",
     below, refers to any such program or work, and a "work based on
     the Program" means either the Program or any derivative work under
     copyright law: that is to say, a work containing the Program or a
     portion of it, either verbatim or with modifications and/or
     translated into another language.  (Hereinafter, translation is
     included without limitation in the term "modification".)  Each
     licensee is addressed as "you".

     Activities other than copying, distribution and modification are
     not covered by this License; they are outside its scope.  The act
     of running the Program is not restricted, and the output from the
     Program is covered only if its contents constitute a work based on
     the Program (independent of having been made by running the
     Program).  Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
     source code as you receive it, in any medium, provided that you
     conspicuously and appropriately publish on each copy an
     appropriate copyright notice and disclaimer of warranty; keep
     intact all the notices that refer to this License and to the
     absence of any warranty; and give any other recipients of the
     Program a copy of this License along with the Program.

     You may charge a fee for the physical act of transferring a copy,
     and you may at your option offer warranty protection in exchange
     for a fee.

  2. You may modify your copy or copies of the Program or any portion
     of it, thus forming a work based on the Program, and copy and
     distribute such modifications or work under the terms of Section 1
     above, provided that you also meet all of these conditions:

       a. You must cause the modified files to carry prominent notices
          stating that you changed the files and the date of any change.

       b. You must cause any work that you distribute or publish, that
          in whole or in part contains or is derived from the Program
          or any part thereof, to be licensed as a whole at no charge
          to all third parties under the terms of this License.

       c. If the modified program normally reads commands interactively
          when run, you must cause it, when started running for such
          interactive use in the most ordinary way, to print or display
          an announcement including an appropriate copyright notice and
          a notice that there is no warranty (or else, saying that you
          provide a warranty) and that users may redistribute the
          program under these conditions, and telling the user how to
          view a copy of this License.  (Exception: if the Program
          itself is interactive but does not normally print such an
          announcement, your work based on the Program is not required
          to print an announcement.)

     These requirements apply to the modified work as a whole.  If
     identifiable sections of that work are not derived from the
     Program, and can be reasonably considered independent and separate
     works in themselves, then this License, and its terms, do not
     apply to those sections when you distribute them as separate
     works.  But when you distribute the same sections as part of a
     whole which is a work based on the Program, the distribution of
     the whole must be on the terms of this License, whose permissions
     for other licensees extend to the entire whole, and thus to each
     and every part regardless of who wrote it.

     Thus, it is not the intent of this section to claim rights or
     contest your rights to work written entirely by you; rather, the
     intent is to exercise the right to control the distribution of
     derivative or collective works based on the Program.

     In addition, mere aggregation of another work not based on the
     Program with the Program (or with a work based on the Program) on
     a volume of a storage or distribution medium does not bring the
     other work under the scope of this License.

  3. You may copy and distribute the Program (or a work based on it,
     under Section 2) in object code or executable form under the terms
     of Sections 1 and 2 above provided that you also do one of the
     following:

       a. Accompany it with the complete corresponding machine-readable
          source code, which must be distributed under the terms of
          Sections 1 and 2 above on a medium customarily used for
          software interchange; or,

       b. Accompany it with a written offer, valid for at least three
          years, to give any third party, for a charge no more than
          your cost of physically performing source distribution, a
          complete machine-readable copy of the corresponding source
          code, to be distributed under the terms of Sections 1 and 2
          above on a medium customarily used for software interchange;
          or,

       c. Accompany it with the information you received as to the
          offer to distribute corresponding source code.  (This
          alternative is allowed only for noncommercial distribution
          and only if you received the program in object code or
          executable form with such an offer, in accord with Subsection
          b above.)

     The source code for a work means the preferred form of the work for
     making modifications to it.  For an executable work, complete
     source code means all the source code for all modules it contains,
     plus any associated interface definition files, plus the scripts
     used to control compilation and installation of the executable.
     However, as a special exception, the source code distributed need
     not include anything that is normally distributed (in either
     source or binary form) with the major components (compiler,
     kernel, and so on) of the operating system on which the executable
     runs, unless that component itself accompanies the executable.

     If distribution of executable or object code is made by offering
     access to copy from a designated place, then offering equivalent
     access to copy the source code from the same place counts as
     distribution of the source code, even though third parties are not
     compelled to copy the source along with the object code.

  4. You may not copy, modify, sublicense, or distribute the Program
     except as expressly provided under this License.  Any attempt
     otherwise to copy, modify, sublicense or distribute the Program is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses
     terminated so long as such parties remain in full compliance.

  5. You are not required to accept this License, since you have not
     signed it.  However, nothing else grants you permission to modify
     or distribute the Program or its derivative works.  These actions
     are prohibited by law if you do not accept this License.
     Therefore, by modifying or distributing the Program (or any work
     based on the Program), you indicate your acceptance of this
     License to do so, and all its terms and conditions for copying,
     distributing or modifying the Program or works based on it.

  6. Each time you redistribute the Program (or any work based on the
     Program), the recipient automatically receives a license from the
     original licensor to copy, distribute or modify the Program
     subject to these terms and conditions.  You may not impose any
     further restrictions on the recipients' exercise of the rights
     granted herein.  You are not responsible for enforcing compliance
     by third parties to this License.

  7. If, as a consequence of a court judgment or allegation of patent
     infringement or for any other reason (not limited to patent
     issues), conditions are imposed on you (whether by court order,
     agreement or otherwise) that contradict the conditions of this
     License, they do not excuse you from the conditions of this
     License.  If you cannot distribute so as to satisfy simultaneously
     your obligations under this License and any other pertinent
     obligations, then as a consequence you may not distribute the
     Program at all.  For example, if a patent license would not permit
     royalty-free redistribution of the Program by all those who
     receive copies directly or indirectly through you, then the only
     way you could satisfy both it and this License would be to refrain
     entirely from distribution of the Program.

     If any portion of this section is held invalid or unenforceable
     under any particular circumstance, the balance of the section is
     intended to apply and the section as a whole is intended to apply
     in other circumstances.

     It is not the purpose of this section to induce you to infringe any
     patents or other property right claims or to contest validity of
     any such claims; this section has the sole purpose of protecting
     the integrity of the free software distribution system, which is
     implemented by public license practices.  Many people have made
     generous contributions to the wide range of software distributed
     through that system in reliance on consistent application of that
     system; it is up to the author/donor to decide if he or she is
     willing to distribute software through any other system and a
     licensee cannot impose that choice.

     This section is intended to make thoroughly clear what is believed
     to be a consequence of the rest of this License.

  8. If the distribution and/or use of the Program is restricted in
     certain countries either by patents or by copyrighted interfaces,
     the original copyright holder who places the Program under this
     License may add an explicit geographical distribution limitation
     excluding those countries, so that distribution is permitted only
     in or among countries not thus excluded.  In such case, this
     License incorporates the limitation as if written in the body of
     this License.

  9. The Free Software Foundation may publish revised and/or new
     versions of the General Public License from time to time.  Such
     new versions will be similar in spirit to the present version, but
     may differ in detail to address new problems or concerns.

     Each version is given a distinguishing version number.  If the
     Program specifies a version number of this License which applies
     to it and "any later version", you have the option of following
     the terms and conditions either of that version or of any later
     version published by the Free Software Foundation.  If the Program
     does not specify a version number of this License, you may choose
     any version ever published by the Free Software Foundation.

 10. If you wish to incorporate parts of the Program into other free
     programs whose distribution conditions are different, write to the
     author to ask for permission.  For software which is copyrighted
     by the Free Software Foundation, write to the Free Software
     Foundation; we sometimes make exceptions for this.  Our decision
     will be guided by the two goals of preserving the free status of
     all derivatives of our free software and of promoting the sharing
     and reuse of software generally.

                                NO WARRANTY

 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
     WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
     LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
     HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
     WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
     FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE
     QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
     PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
     SERVICING, REPAIR OR CORRECTION.

 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
     WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
     MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
     LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
     INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
     INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
     DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
     OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
     OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
     ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

                      END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs
=============================================

   If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.

   To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least the
"copyright" line and a pointer to where the full notice is found.

     ONE LINE TO GIVE THE PROGRAM'S NAME AND AN IDEA OF WHAT IT DOES.
     Copyright (C) 19YY NAME OF AUTHOR
     
     This program 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 of the License, or (at your
     option) any later version.
     
     This program 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 this program; if not, write to the Free Software Foundation, Inc.,
     59 Temple Place, Suite 330, Boston, MA 02111, USA.

   Also add information on how to contact you by electronic and paper
mail.

   If the program is interactive, make it output a short notice like
this when it starts in an interactive mode:

     Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR
     Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type
     `show w'.  This is free software, and you are welcome to redistribute it
     under certain conditions; type `show c' for details.

   The hypothetical commands `show w' and `show c' should show the
appropriate parts of the General Public License.  Of course, the
commands you use may be called something other than `show w' and `show
c'; they could even be mouse-clicks or menu items--whatever suits your
program.

   You should also get your employer (if you work as a programmer) or
your school, if any, to sign a "copyright disclaimer" for the program,
if necessary.  Here is a sample; alter the names:

     Yoyodyne, Inc., hereby disclaims all copyright
     interest in the program `Gnomovision'
     (which makes passes at compilers) written
     by James Hacker.
     
     SIGNATURE OF TY COON, 1 April 1989
     Ty Coon, President of Vice

   This General Public License does not permit incorporating your
program into proprietary programs.  If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library.  If this is what you want to do, use the
GNU Library General Public License instead of this License.


File: groff.info,  Node: Introduction,  Next: Invoking groff,  Prev: Copying,  Up: Top

Introduction
************

   GNU `troff' (or `groff') is a system for typesetting documents.
`troff' is very flexible and has been in existence (and use) for about
3 decades.  It is quite widespread and firmly entrenched in the UNIX
community.

* Menu:

* What Is groff?::
* History::
* groff Capabilities::
* Macro Packages::
* Preprocessors::
* Postprocessors::
* Credits::


File: groff.info,  Node: What Is groff?,  Next: History,  Prev: Introduction,  Up: Introduction

What Is `groff'?
================

   `groff' belongs to an older generation of document preparation
systems, which operate more like compilers than the more recent
interactive "WYSIWYG"(1) (*note What Is groff?-Footnote-1::) systems.
`groff' and its contemporary counterpart, TeX, both work using a "batch"
paradigm: the input (or "source") files are normal text files with
embedded formatting commands.  These files can then be processed by
`groff' to produce a typeset document on a variety of devices.

   Likewise, `groff' should not be confused with a "word processor",
since that term connotes an integrated system which includes an editor
and a text formatter.  Also, many word processors follow the WYSIWYG
paradigm which was discussed earlier.

   Although WYSIWYG systems may be easier to use, they have a number of
disadvantages compared to `troff':

   * They must be used on a bitmapped display to do any operations on
     your document.

   * Most of the WYSIWYG systems are either non-free or are not very
     portable.

   * `troff' is firmly entrenched in all UNIX systems.

   * It is difficult to have a wide range of capabilities available
     within the confines of a GUI/window system.

   * It is more difficult to make global changes to a document.

     "GUIs normally make it simple to accomplish simple actions and
     impossible to accomplish complex actions."  -Doug Gwyn (22/Jun/91
     in `comp.unix.wizards')


File: groff.info,  Node: What Is groff?-Footnotes,  Up: What Is groff?

   (1) What You See Is What You Get


File: groff.info,  Node: History,  Next: groff Capabilities,  Prev: What Is groff?,  Up: Introduction

History
=======

   `troff' can trace its origins back to a formatting program called
`runoff' which ran on MIT's CTSS system.  This name came from the
common phrase of the time "I'll run off a document."

   The first version of UNIX was developed on a PDP-7 which was sitting
around Bell Labs.  In 1971 the developers wanted to get a PDP-11 for
further work on the operating system.  In order to justify the cost for
this system, they proposed that they would implement a document
formatting system for the AT&T patents division.  This first formatting
program was a reimplementation of `runoff'.  In accordance with UNIX's
penchant for abreviations, it was named `roff' (an abreviation of
`runoff').

   When they needed a more flexible language, a new version of `roff'
called `nroff' ("Newer `roff'") was written.  It had a much more
complicated syntax, but provided the basis for all future versions.
When they got a Graphic Systems CAT Phototypesetter, J. F.  Ossanna
wrote a version of `nroff' which would drive it.  It was dubbed
`troff', for "typesetter `roff'", although many people have speculated
that it actually means "Times `roff'" because of `troff''s use of the
Times font family by default.  As such, the name `troff' is pronounced
tee-roff rather than trough.

   With `troff' came `nroff' (they were actually the same program
except for some `#ifdef's), which was for producing output for line
printers and ASCII terminals.  It understood everything `troff' did,
and ignored the commands which were not applicable (i.e. font changes).

   Since there are several things which cannot be done easily in
`troff', work on several preprocessors began.  These programs would
transform certain parts of a document into `troff', which made a very
natural use of pipes in UNIX.

   The `eqn' preprocessor allowed mathematical formulae to be specified
in a much simpler and more intuitive manner.  `tbl' is a preprocessor
for formatting tables.  The `refer' preprocessor (and the similar
program, `bib') processes citations in a document according to a
bibliographic database.

   Unfortunately, Ossanna's `troff' was written in PDP-11 assembly
language and produced output specifically for the CAT phototypesetter.
He rewrote it in C, although it was now 7000 lines of uncommented code
and still dependent on the CAT.  As the CAT became less common, and was
no longer supported by the manufacturer, the need to make it support
other devices became a priority.  However, before this could be done,
Ossanna was killed in an auto accident.

   So, Brian Kernighan took on the task of rewriting `troff'.  The
newly rewritten version produced a device independent code which was
very easy for postprocessors to read and translate to the appropriate
printer codes.  Also, this new version of `troff' (called `ditroff')
had several extensions, which included drawing functions.

   Due to the additional abilities of the new version of `troff',
several new preprocessors appeared.  The `pic' preprocessor provides a
wide range of drawing functions.  Likewise the `ideal' preprocessor did
the same, although via a much different paradigm.  The `grap'
preprocessor took specifications for graphs, but, unlike other
preprocessors, produced `pic' code.

   James Clark began work on a GNU implementation of `ditroff' in
early 1989.  The first version, `groff' 0.3.1, was released June 1990.
`groff' included:

   * a replacement for `ditroff' with many extentions;

   * the `soelim', `pic', `tbl', and `eqn' preprocessors;

   * postprocessors for ASCII devices, PostScript, TeX DVI, and
     X windows;

   * a version of the `-me' macros and an implementation of the `-man'
     macros.

   * a front-end which could construct the (sometimes painfully long)
     pipelines required for all the post- and preprocessors.

   GNU `troff' also eliminated the need for a separate `nroff' program
with a postprocessor which would produce ASCII output.

   Development of GNU `troff' progressed rapidly, and saw the additions
of a replacement for `refer', an implementation of the `-ms' and `-mm'
macros, and a program to deduce how to format a document (`grog').

   It was declared a stable (i.e. non beta) package with the release of
version 1.04 around November 1991.


File: groff.info,  Node: groff Capabilities,  Next: Macro Packages,  Prev: History,  Up: Introduction

`groff' Capabilities
====================

   So what exactly is `groff' capable of doing?  `groff' provides a
wide range of low-level text formatting operations.  Using these, you
can perform a wide range of formatting tasks, such as footnotes, table
of contents, multiple columns, etc.  Here's a list of the operations
supported by `groff':

   * text filling, adjusting, and centering

   * hyphenation

   * page control

   * font and character size control

   * vertical spacing (i.e. double spacing)

   * line length and indenting

   * macros, strings, diversions, and traps

   * number registers

   * tabs, leaders, and fields

   * input and output conventions and character translation

   * overstrike, bracket, line drawing, and zero-width functions

   * local horizontal and vertical motions and the width function

   * three-part titles

   * output line numbering

   * conditional acceptance of input

   * environment switching

   * insertions from the standard input

   * input/output file switching

   * output and error messages


File: groff.info,  Node: Macro Packages,  Next: Preprocessors,  Prev: groff Capabilities,  Up: Introduction

Macro Packages
==============

   Since `groff' provides such low-level facilities, it can be quite
difficult to use by itself.  However, `groff' provides a "macro"
facility which allows you to specify how certain routine operations
(e.g., starting paragraphs, printing headers and footers, etc.) should
be done.  These macros can be collected together into a "macro
package".  There are a number of macro packages available; the most
common (and the ones described in this manual) are `-man', `-me',
`-ms', and `-mm'.


File: groff.info,  Node: Preprocessors,  Next: Postprocessors,  Prev: Macro Packages,  Up: Introduction

Preprocessors
=============

   Although `groff' provides most functions needed to format a
document, some operations would be unwieldy (e.g., drawing pictures).
Therefore, programs called preprocessors were written which understand
their own language and produce the necessary groff operations.  These
preprocessors are able to differentiate their own input from the rest of
the document via markers.

   To use a preprocessor, UNIX pipes are used to feed the output from
the preprocessor into `groff'.  Any number of preprocessors may be used
on a given document; in this case, the preprocessors are linked
together into one pipeline.  However, in `groff', the user does not
need to construct the pipe, but only to tell `groff' what preprocessors
to use.

   `groff' currently has preprocessors for producing tables (`tbl'),
typesetting equations (`eqn'), drawing pictures (`pic'), and for
processing bibliographies (`refer').  An associated program which is
useful when dealing with preprocessors is `soelim'.

   There are other preprocessors in existence, but there are,
unfortunately, no free implementations available.  These are
preprocessors for drawing pictures (`ideal' and `gremlin'), for drawing
graphs (`grap'), and for drawing chemical structures (`chem').


File: groff.info,  Node: Postprocessors,  Next: Credits,  Prev: Preprocessors,  Up: Introduction

Postprocessors
==============

   `groff' actually produces device independent code which may be fed
into a postprocessor which will produce output for a particular device.
Currently, `groff' has postprocessors for PostScript devices, LaserJet
printers, ASCII terminals, graphics terminals on X windows (for
previewing), TeX DVI format, and HTML.


File: groff.info,  Node: Credits,  Prev: Postprocessors,  Up: Introduction

Credits
=======

   Large portions of this manual were taken from existing documents,
most notably, the manual pages for the `groff' package by James Clark,
and Eric Allman's papers on the `-me' macro package.


File: groff.info,  Node: Invoking groff,  Next: Tutorial for Macro Users,  Prev: Introduction,  Up: Top

Invoking `groff'
****************

   This section focuses on how to invoke the `groff' front end.  This
front end takes care of the details of constructing the pipeline among
the preprocessors, `gtroff' and the postprocessor.

   It has become a tradition that GNU programs get the prefix "g" to
distinguish them from their original counterparts provided by the host
(see *Note Environment::, for more details).  Thus, for example, `geqn'
is GNU `eqn'.  On operating systems like Linux or the Hurd, which don't
contain proprietary software, and on MS-DOS/MS-Windows, where `troff'
and associated programs are not available at all, this prefix is
omitted since GNU `troff' is the only used incarnation of `troff'.
Exception: `groff' is never replaced by `roff'.

* Menu:

* Options::
* Environment::
* Invocation Examples::


File: groff.info,  Node: Options,  Next: Environment,  Prev: Invoking groff,  Up: Invoking groff

Options
=======

   `groff' is a front-end to the groff document formatting system.
Normally, it runs the `gtroff' program and a postprocessor appropriate
for the selected device.  The default device is `ps' (but it can be
changed when `groff' is configured and built).  It can optionally
preprocess with any of `gpic', `geqn', `gtbl', `grefer', or `gsoelim'.

   This section only documents options to the `groff' front end.  Many
of the arguments to `groff' are passed on to `gtroff', therefore those
are also included.

   The command line format for `groff' is:

     groff [ -abehilpstvzCENRSVXZ ] [ -FDIR ] [ -mNAME ]
           [ -TDEF ] [ -fFAM ] [ -wNAME ] [ -WNAME ]
           [ -MDIR ] [ -dCS ] [ -rCN ] [ -nNUM ]
           [ -oLIST ] [ -PARG ] [ -LARG ]
           [ FILES... ]

   The command line format for `gtroff' is as follows:

     gtroff [ -abivzCER ] [ -wNAME ] [ -WNAME ] [ -dCS ]
            [ -fFAM ] [ -mNAME ] [ -nNUM ]
            [ -oLIST ] [ -rCN ] [ -TNAME ]
            [ -FDIR ] [ -MDIR ] [ FILES... ]

As you can see, many of the options to `groff' are actually passed on
to `gtroff'.

   Options without an argument can be grouped behind a single `-'.  A
filename of `-' denotes the standard input.

   The `grog' command can be used to guess the correct `groff' command
to use to format a file.

   Here's the description of the command-line options:

`-h'
     Print a help message.

`-e'
     Preprocess with `geqn'.

`-t'
     Preprocess with `gtbl'.

`-p'
     Preprocess with `gpic'.

`-s'
     Preprocess with `gsoelim'.

`-R'
     Preprocess with `grefer'.  No mechanism is provided for passing
     arguments to `grefer' because most `grefer' options have
     equivalent commands which can be included in the file.

     Note that `gtroff' also accepts a `-R' option, which is not
     accessible via `groff'.  This option prevents the loading of the
     `troffrc' file.

`-v'
     Make programs run by `groff' print out their version number.

`-V'
     Print the pipeline on stdout instead of executing it.

`-z'
     Suppress output from `gtroff'.  Only error messages will be
     printed.

`-Z'
     Do not postprocess the output of `gtroff'.  Normally `groff' will
     automatically run the appropriate postprocessor.

`-PARG'
     Pass ARG to the postprocessor.  Each argument should be passed
     with a separate `-P' option. Note that groff does not prepend `-'
     to ARG before passing it to the postprocessor.

`-l'
     Send the output to a printer.  The command used for this is
     specified by the print command in the device description file.

`-LARG'
     Pass ARG to the spooler.  Each argument should be passed with a
     separate `-L' option.  Note that `groff' does not prepend a `-' to
     ARG before passing it to the spooler.

`-TDEV'
     Prepare output for device DEV.  The default device is `ps', unless
     changed when `groff' was configured and built.  The following are
     the output devices currently available:
    `ps'
          For PostScript printers and previewers.

    `dvi'
          For TeX DVI format.

    `X75'
          For a 75dpi X11 previewer.

    `X100'
          For a 100dpi X11 previewer.

    `ASCII'
          For typewriter-like devices.

    `latin1'
          For typewriter-like devices that support the ISO Latin-1
          character set.

    `lj4'
          For an HP LaserJet4-compatible (or other PCL5-compatible)
          printer.

    `html'
          To produce HTML output.

     The postprocessor to be used for a device is specified by the
     `postpro' command in the device description file.  (*Note Font
     Files::, for more info.)  This can be overridden with the `-X'
     option.

`-X'
     Preview with `gxditview' instead of using the usual postprocessor.
     This is unlikely to produce good results except with `-Tps'.

`-N'
     Don't allow newlines with `eqn' delimiters.  This is the same as
     the `-N' option in `geqn'.

`-S'
     Safer mode.  Pass the `-S' option to `gpic' and use the `-msafer'
     macros with `gtroff'.

`-a'
     Generate an ASCII approximation of the typeset output.

`-b'
     Print a backtrace with each warning or error message.  This
     backtrace should help track down the cause of the error.  The line
     numbers given in the backtrace may not always be correct:
     `troff''s idea of line numbers gets confused by `as' or `am'
     requests.

`-i'
     Read the standard input after all the named input files have been
     processed.

`-wNAME'
     Enable warning NAME.  Available warnings are described in *Note
     Debugging::.  Multiple `-w' options are allowed.

`-WNAME'
     Inhibit warning NAME.  Multiple `-W' options are allowed.

`-E'
     Inhibit all error messages.

`-C'
     Enable compatibility mode.  *Note Implementation Differences::,
     for the list of incompatibilites between `groff' and traditional
     Unix `troff'.

`-dCS'
`-dNAME=s'
     Define C or NAME to be a string S; C must be a one-letter NAME.

`-fFAM'
     Use FAM as the default font family.

`-mNAME'
     Read in the file `tmac.NAME'.  Normally this will be searched for
     in `groff''s `lib/' directory.

`-nNUM'
     Number the first page NUM.

`-oLIST'
     Output only pages in LIST, which is a comma-separated list of page
     ranges; `N' means print page N, `M-N' means print every page
     between M and N, `-N' means print every page up to N, `N-' means
     print every page beginning with N.  `troff' will exit after
     printing the last page in the list.  All the ranges are inclusive
     on both ends.

`-rCN'
`-rNAME=N'
     Set a numerical register C or NAME to the value N; C must be a
     one-letter NAME; N can be any troff numeric expression.

`-FDIR'
     Search `DIR' for subdirectories `devNAME' (NAME is the name of the
     device), for the `DESC' file and for font files before the normal
     directory.

`-MDIR'
     Search directory `DIR' for macro files before the normal directory.


File: groff.info,  Node: Environment,  Next: Invocation Examples,  Prev: Options,  Up: Invoking groff

Environment
===========

   Several environment variables modify `groff''s behavior:

`GROFF_COMMAND_PREFIX'
     If this is set to X, then `groff' will run `Xtroff' instead of
     `gtroff'.  This also applies to `tbl', `pic', `eqn', `refer', and
     `soelim'.  It does *not* apply to `grops', `grodvi', `grotty',
     `grohtml', `grolj4', and `gxditview'.

`GROFF_TMAC_PATH'
     A colon-separated list of directories in which to search for macro
     files.

`GROFF_TYPESETTER'
     The default device.

`GROFF_FONT_PATH'
     A colon-separated list of directories in which to search for the
     `devNAME' directories.

`PATH'
     The search path for commands executed by groff.

`GROFF_TMPDIR'
     The directory in which temporary files will be created.  If this
     is not set and `TMPDIR' is set, temporary files will be created in
     that directory.  Otherwise temporary files will be created in
     `/tmp'.  The `grops' and `grefer' commands can create temporary
     files.

   Note that MS-DOS and MS-Windows ports of `groff' use semi-colons,
rather than colons, to separate the directories in the lists described
above.


File: groff.info,  Node: Invocation Examples,  Prev: Environment,  Up: Invoking groff

Invocation Examples
===================

   This section will list several common uses of `groff' and the
command line which will accomplish it.

     groff file
     groff -X -me file
     groff -mm -rD1 -z file
     groff -tps -me file | lpr -Plw2
     ... any more?? ...

`grog'
------

   `grog' reads files, guesses which of the `groff' preprocessors
and/or macro packages are required for formatting them, and prints the
`groff' command including those options on the standard output.  The
options generated are one of `-e', `-man', `-me', `-mm', `-ms', `-p',
`-s', and `-t'.

   A filename of `-' is taken to refer to the standard input.  If no
files are specified the standard input will be read.  Any specified
options will be included in the printed command.  No space is allowed
between options and their arguments.  For example,

     `grog -Tdvi paper.ms`

will guess the approriate command to print `paper.ms' and then run it
after adding the `-Tdvi' option.


File: groff.info,  Node: Tutorial for Macro Users,  Next: Programming Tutorial,  Prev: Invoking groff,  Up: Top

Tutorial for Macro Users
************************

   Most users tend to use a macro package to format their papers.  This
means that the whole breadth of `groff' is not neccessary for most
people.  This chapter covers the material needed to efficiently use a
macro package.

* Menu:

* Basics::
* Common Features::


File: groff.info,  Node: Basics,  Next: Common Features,  Prev: Tutorial for Macro Users,  Up: Tutorial for Macro Users

Basics
======

   This section covers some of the basic concepts you will need to
understand how to use a macro package(1) (*note Basics-Footnote-1::).
References are made throughout to more detailed information, if desired.

   `groff' reads an input file prepared by the user and outputs a
formatted paper suitable for publication or framing.  The input consists
of text, or words to be printed, and embedded commands ("requests" and
"escapes"), which tell `groff' how to format the printed copy.  For
more detail on this, see *Note Embedded Commands::.

   The word "argument" is used in this chapter to mean a word or number
which appears on the same line as a request and which modifies the
meaning of that request.  For example, the request

     .sp

spaces one line, but

     .sp 4

spaces four lines.  The number 4 is an argument to the `sp' request
which says to space four lines instead of one.  Arguments are separated
from the request and from each other by spaces.  More details on this
can be found in *Note Request Arguments::.

   The primary function of `groff' is to collect words from input
lines, fill output lines with those words, justify the right-hand margin
by inserting extra spaces in the line, and output the result.  For
example, the input:

     Now is the time
     for all good men
     to come to the aid
     of their party.
     Four score and seven
     years ago,...

will be read, packed onto output lines, and justified to produce:

     Now is the time for all good men to come to the aid of their party.
     Four score and seven years ago,...

   Sometimes you may want to start a new output line even though the
line you are on is not yet full; for example, at the end of a
paragraph.  To do this you can cause a "break", which starts a new
output line.  Some requests cause a break automatically, as do blank
input lines and input lines beginning with a space.

   Not all input lines are text to be formatted.  Some of the input
lines are requests which describe how to format the text.  Requests
always have a period or an apostrophe (`'') as the first character of
the input line.

   The text formatter also does more complex things, such as
automatically numbering pages, skipping over page boundaries to put
footnotes in the correct place, and so forth.

   Here are a few hints for preparing text for input to `groff'.  First,
keep the input lines short.  Short input lines are easier to edit, and
`groff' will pack words onto longer lines for you anyhow.  In keeping
with this, it is helpful to begin a new line after every period, comma,
or phrase, since common corrections are to add or delete sentences or
phrases.  Secondly, do not hyphenate words at the end of lines -
`groff' is smart enough to hyphenate words for you as needed, but is
not smart enough to take hyphens out and join a word back together.
Also, words such as "mother-in-law" should not be broken over a line,
since then you will get a space where not wanted, such as "mother-
in-law".

   Groff will double space output text automatically if you use the
request `.ls 2'.  You can revert to single spaced mode by typing `.ls
1'.

   A number of requests allow you to change the way the printed copy
looks, sometimes called the "layout" of the output page.  Most of these
requests adjust the placing of "white space" (blank lines or spaces).

   The `.bp' request starts a new page.  *Note Page Control::, for more
details.

   The request `.sp N' leaves N lines of blank space.  N can be omitted
(meaning skip a single line) or can be of the form Ni (for N inches) or
Nc (for N centimeters).  For example, the input:

     .sp 1.5i
     My thoughts on the subject
     .sp

leaves one and a half inches of space, followed by the line "My
thoughts on the subject", followed by a single blank line.

   Text lines can be centered by using the `.ce' request.  The line
after `.ce' is centered (horizontally) on the page.  To center more
than one line, use `.ce N' (where N is the number of lines to center),
followed by the N lines.  If you want to center many lines but don't
want to count them, type:

     .ce 1000
     lines to center
     .ce 0

The `.ce 0' request tells `groff' to center zero more lines, in other
words, stop centering.

   All of these requests cause a break; that is, they always start a new
line.  If you want to start a new line without performing any other
action, use `.br'.


File: groff.info,  Node: Basics-Footnotes,  Up: Basics

   (1) This section is derived from `Writing Papers with nroff using
-me' by Eric P. Allman.


File: groff.info,  Node: Common Features,  Prev: Basics,  Up: Tutorial for Macro Users

Common Features
===============

   Groff provides very low level operations for formatting a document.
There are many common routine operations which are done in all
documents.  These common operations are written into "macros" and
collected into a "macro package".

   All macro packages provide certain common capabilities which fall
into the following categories.

Paragraphs
----------

   One of the most common and most used capability is starting a
paragraph.  There are a number of different types of paragraphs, any of
which can be initiated with macros supplied by the macro package.
Normally paragraphs start with a blank line and the first line
indented, like the text in this manual.  There are also block style
paragraphs, which omit the indentation:

     Some   men  look   at  constitutions   with  sanctimonious
     reverence, and deem them like the ark of the covenant, too
     sacred to be touched.

   And there are also indented paragraphs which begin with a tag or
label at the margin and the remaining text indented.

     one   This is  the first paragraph.  Notice  how the first
           line of  the resulting  paragraph lines up  with the
           other lines in the paragraph.
     longlabel
           This  paragraph   had  a  long   label.   The  first
           character of text on the first line will not line up
           with  the  text  on  second  and  subsequent  lines,
           although they will line up with each other.

   A variation of this is a bulleted list....

Sections and Chapters
---------------------

   Most macro packages supply some form of section headers.  The
simplest kind is simply the heading on a line by itself in bold type.
Others supply automatically numbered section heading or different
heading styles at different levels.  Some, more sophisticated, macro
packages supply macros for starting chapters and appendicies.

Headers and Footers
-------------------

   Every macro packages gives you some way to manipulate the headers and
footers (or "titles") on each page.  Some packages will allow you to
have different ones on the even and odd pages (for material printed in
a book form).  The titles are called three-part titles, that is, there
is a left-justified part, a centered part, and a right-justified part.
An automatically generated page number may be put in any of these
fields with the `%' character.

Page Layout
-----------

   Most macro packages let you specify top and bottom margins and other
details about the appearance of the printed pages.

Displays
--------

   Displays are sections of text to be set off from the body of the
paper.  Major quotes, tables, and figures are types of displays, as are
all the examples used in this document.

   Major quotes are quotes which are several lines long, and hence are
set in from the rest of the text without quote marks around them.

   A list is an indented, single spaced, unfilled display.  Lists should
be used when the material to be printed should not be filled and
justified like normal text, such as columns of figures or the examples
used in this paper.

   A keep is a display of lines which are kept on a single page if
possible.  An example of where you would use a keep might be a diagram.
Keeps differ from lists in that lists may be broken over a page
boundary whereas keeps will not.

   Floating keeps move relative to the text.  Hence, they are good for
things which will be referred to by name, such as "See figure 3".  A
floating keep will appear at the bottom of the current page if it will
fit; otherwise, it will appear at the top of the next page.  Meanwhile,
the surrounding text will `flow' around the keep, thus leaving now
blank areas.

Footnotes and annotations
-------------------------

   There are a number of requests to save text for later printing.
Footnotes are printed at the bottom of the current page.  Delayed text
is intended to be a variant form of foot- note; the text is printed
only when explicitly called for, such as at the end of each chapter.

   Delayed text is very similar to a footnote except that it is printed
when called for explicitly.  This allows a list of references to appear
(for example) at the end of each chapter, as is the convention in some
disciplines.

   Most macro packages which supply this functionality also supply a
means of automatically numbering either type of annotation.

Table of Contents
-----------------

   Tables of contents are a type of delayed text having a tag (usually
the page number) attached to each entry after a row of dots.  The table
accumulates throughought the paper until printed, usually after the
paper has ended.  Many macro packages will provide the abilitly to have
several tables of contents (i.e. one standard one, one for tables, &c.)

Indexes
-------

   While some macro packages will use the term "index", none actually
provide that functionality.  The facilities they call indexes are
actually more appropriate for tables of contents.

Paper formats
-------------

   Some macro packages provide stock formats for various kinds of
documents.  Many of them provide a common format for the title and
opening pages of a technical paper.  The -mm macros in particular
provide formats for letters and memorandums.

Multiple Columns
----------------

   Some macro packages (except -man) provide the ability to have two or
more columns on a page.

Font and Size changes
---------------------

   The builtin font and size functions are not always intuitive, so all
macro packages provide macros to make these operations simpler.

Predefined Strings
------------------

   Most macro packages provide various predefined strings for a variety
of uses, examples are sub- and super-scripts, printable dates, quotes
and various special characters.

Preprocessor Support
--------------------

   All macro packages provide support for the various preprocessors.

Configuration and Customization
-------------------------------

   Some macro packages provide means of customizing many of details of
how the package behaves.  This ranges from setting the default type
size to changing the appearance of section headers.


File: groff.info,  Node: Programming Tutorial,  Next: File formats,  Prev: Tutorial for Macro Users,  Up: Top

Programming Tutorial
********************

   This chapter covers *all* of the facilities of groff.  If you are
intending to use a macro package, you probably do not want to read this
chapter.

* Menu:

* Text::
* Input Conventions::
* Measurements::
* Expressions::
* Identifiers::
* Embedded Commands::
* Registers::
* Manipulating Filling and Adjusting::
* Manipulating Hyphenation::
* Manipulating Spacing::
* Tabs and Fields::
* Character Translations::
* Line Layout::
* Page Layout::
* Page Control::
* Fonts::
* Sizes::
* Strings::
* Conditionals and Loops::
* Writing Macros::
* Page Motions::
* Drawing Functions::
* Traps::
* Diversions::
* Environments::
* I/O::
* Postprocessor Access::
* Miscellany::
* Debugging::
* Implementation Differences::
* Summary::


File: groff.info,  Node: Text,  Next: Input Conventions,  Prev: Programming Tutorial,  Up: Programming Tutorial

Text
====

   `groff' input files contain text with control commands interspersed
throughout.  But, even without control codes, `groff' will still do
several things with your text: filling and adjusting, adding additional
space after sentences, hyphenating and inserting implicit line breaks.

* Menu:

* Filling and Adjusting::
* Hyphenation::
* Sentences::
* Tab Stops::
* Implicit Line Breaks::


File: groff.info,  Node: Filling and Adjusting,  Next: Hyphenation,  Prev: Text,  Up: Text

Filling and Adjusting
---------------------

   When `troff' reads in text it collects words from input and fits as
many of them together on one output line as it can.  This is known as
"filling".

   Once `troff' has a "filled" line it will try to "adjust" it.  which
means it will widen the spacing between words until the text reaches
the right margin (in the default adjustment mode).  Extra spaces
between words are preserved, but spaces at the end of lines are ignored.
Spaces at the front of a line will cause a "break".  (Breaks will be
explained in *Note Implicit Line Breaks::.)

   *Note Manipulating Filling and Adjusting::.


File: groff.info,  Node: Hyphenation,  Next: Sentences,  Prev: Filling and Adjusting,  Up: Text

Hyphenation
-----------

   Since the odds of finding a set of words, for every output line,
which will fit nicely on a line without inserting excessive amounts of
space between words are not great, troff will hyphenate words so that
lines can be justified without there being too much space between words.
It uses an internal hyphenation algorithm, to indicate which words can
be hyphenated and how to do so.  When a word is hyphenated the first
part of the word will be added to the current filled line being output
(with an attached hyphen), and the other portion will be added to the
next line to be filled.

   *Note Manipulating Hyphenation::.


File: groff.info,  Node: Sentences,  Next: Tab Stops,  Prev: Hyphenation,  Up: Text

Sentences
---------

   Although it is often debated, some typesetting rules say there
should be different amounts of space after various puctuation marks.
For example, a period at the end of a sentence should have twice as
much space following it as would a comma or a period as part of an
abbreviation.

   Troff does this by flagging certain characters (normally `!',  `?'
and `.') as "end of sentence" characters.  When `troff' encounters one
of these characters at the end of a line it will append two "sentence
spaces" in the formatted output.  (thus, one of the conventions
mentioned in *Note Input Conventions::).


File: groff.info,  Node: Tab Stops,  Next: Implicit Line Breaks,  Prev: Sentences,  Up: Text

Tab Stops
---------

   Groff translates tabs in the input into movements to the next tab
stop.  These tab stops are initially located every half inch across the
page.  Using this you can make simple tables.  However, this can often
be deceptive as the appearance (and width) of your text on a terminal
and the results from groff can vary greatly.

   Also, a possible sticking point is that lines beginning with tab
characters will still be filled, again producing unexpected results.
For example, the following input

     	1	2	3
     		4	5

will produce

     	1	2	3		4	5

   *Note Tabs and Fields::.


File: groff.info,  Node: Implicit Line Breaks,  Prev: Tab Stops,  Up: Text

Implicit Line Breaks
--------------------

   An important concept in `troff' is the "break".  When a "break"
occurs, `troff' will output the partially filled line (unadjusted), and
resume collecting and filling text on the next output line.

   There are several ways to cause a break in `troff'.  A blank line
will not only cause a break, but it will also cause a one line vertical
space (effectively a blank line) to be output.

   A line which begins with a space will cause a break and the space
will be output at the beginning of the next line.  Note that this space
isn't adjusted, even in fill mode.

   The end of file will also cause a break (otherwise the last line of
your document may vanish!)

   Certain "requests" also cause breaks, implicitly or explicity.  This
will be discussed later.

   *Note Manipulating Filling and Adjusting::.


File: groff.info,  Node: Input Conventions,  Next: Measurements,  Prev: Text,  Up: Programming Tutorial

Input Conventions
=================

   Since `groff' does filling automatically, it is traditional in
`groff' not to try and type things in as nicely formatted paragraphs.
These are some conventions commonly used when typing `groff' text:

   * Break lines after punctuation, particularily at the ends of
     sentences, and in other logical places.  Keep separate phrases on
     lines by themselves, as entire phrases are often added or deleted
     when editing.

   * Try to keep lines less than 40-60 characters, to allow space for
     inserting more text.

   * Do not try to do any formatting in a WYSIWYG manner (i.e. don't
     try and use spaces to get proper indentation).


File: groff.info,  Node: Measurements,  Next: Expressions,  Prev: Input Conventions,  Up: Programming Tutorial

Measurements
============

   Troff (like any other programs) requires numeric parameters to
specify various measurements.  Most numeric parameters (those that
specify vertical or horizontal motion or a type size) may have a
measurement unit attached.  These units are specified as a single
character which immediately follows the number or expression.  Each of
these units are understood, by `troff', to be a multiple of its "basic
unit".  So, whenever a different measurement unit is specified `troff'
converts this into its basic units.  This basic unit, represented by a
`u' is a device dependent measurement which is quite small, ranging from
1/75th to 1/72000th of an inch.

   Some of the measurement units are completely independent of any of
the current settings (e.g. type size) of `groff'.

`i'
     Inches.  An antiquated measurement unit still in use in certain
     backwards countries.

`c'
     Centimeters.

`p'
     Points.  This is a typesetter's measurement used for measure type
     size.  It is 72 points to an inch.

`P'
     Pica.  Another typesetting measurement.  6 Picas to an inch.

`s'

`z'
   The other measurements understood by `troff' are dependent on
settings currently in effect in `troff'.  These are very useful for
specifying measurements which should look proper with any size of text.

`m'
     Ems.  This unit is equal to the current font size in points.  So
     called because it is _approximately_ the width of the letter `m'
     in the current font.

`n'
     Ens.  This is half of an em.

`v'
     Vertical space.  This is equivalent to the current line spacing.
     *Note Sizes::, for more information about this.

`M'
     100ths of an em.

   *Note Fractional Type Sizes::.

* Menu:

* Default Units::


File: groff.info,  Node: Default Units,  Prev: Measurements,  Up: Measurements

Default Units
-------------

   Many requests take a default unit.  While this can be helpful at
times, it can cause strange errors in some expressions.  For example,
the line  length  request  expects  em's.  Here are several attempts to
get 3.5 inches and the results:

     3.5i      =>   3.5i
     7/2       =>   0i
     7/2i      =>   0i
     7i/2      =>   .1i
     7i/2u     =>   3.5i

   As you can see, the safest way to specify measurements is to always
attach a scaling indicator.


File: groff.info,  Node: Expressions,  Next: Identifiers,  Prev: Measurements,  Up: Programming Tutorial

Expressions
===========

   Troff has most of operators common to other languages:

   * Arithmetic: +, -, /, *, %

   * Comparison: <, >, >=, <=, =, ==  (the last two are the same)

   * Logical: &, :

   * Unary operators: -, +, ! (if/while only??)

   * Maximum and minimum: >?, <?

   * Scaling: (C;E) Evaluate E using C as the default scaling indicator.
     If C is missing, ignore scaling indicators in the evaluation of E.

   Parentheses may be used as in any other language.  However, in
`groff' they are necessary to ensure order of evaluation.  Groff has no
operator precedence, expressions are evaluated left to right.  This
means that `3+5*4' is evaluated as if it were parenthesized like
`(3+5)*4', not as `3+(5*4)', like you may expect.

   For many requests which cause a motion on the page, the unary
operators work differently.  The `+' and `-' operators indicate a
motion relative to the current position (down or up, respectively).
The `|' operator indicates an absolute position on the page or input
line. `+' and `-' are also treated differently by `nr'.  Due to the way
arguments are parsed, spaces are not allowed in expressions, unless the
entire expression is surrounded by parenthesis.

   *Note Request Arguments::.  *Note Conditionals and Loops::.


File: groff.info,  Node: Identifiers,  Next: Embedded Commands,  Prev: Expressions,  Up: Programming Tutorial

Identifiers
===========

   Like any other language, `troff' has rules for properly formed
identifiers.  In `troff', an identifier can be made up of most any
printable character.  The only exception is characters which are
interpreted by `troff' (backslash, square bracket and `?').  So, for
example, any of the following are valid:

     br
     PP
     (l
     end-list
     @_

   You can test whether an identifier is valid in `groff' with the `\A'
escape.  It expands to 1 or 0 according whether its argument (given in
quotes) is or is not acceptable as the name of a string, macro,
diversion, number register, environment or font. It will return 0 if no
argument is given. This is useful if you want to lookup user input in
some sort of associative table.

   Identifiers in `groff' can be any length, but, in some contexts,
`groff' needs to be told where identifiers end and text begins (and in
different ways depending on their length):

   * Single character

   * Two characters: must be prefixed with `(' in some situations.

   * Arbitrary length (`groff' only): must be bracketed with `[', `]'
     in some situations.  Any length identifier can be put in brackets.

   Unlike many other programming languages, undefined identifiers are
silently ignored or expanded to nothing.

   *Note Interpolating Registers::.  *Note Strings::.


File: groff.info,  Node: Embedded Commands,  Next: Registers,  Prev: Identifiers,  Up: Programming Tutorial

Embedded Commands
=================

   With most documents you need more funtionality beyond filling,
adjusting and implicit line breaking.  In order to gain further
functionality, `groff' allows commands to be embeded into your text, in
two ways.

   The first is a "request" which takes up an entire line, and does
some large scale operation (e.g. break lines, start new pages).

   The other is an "escape" which can be embedded anywhere in your
text, or even as an argument to a request. Escapes generally do more
minor operations like sub- and super- scripts, print a symbol, etc.

* Menu:

* Requests::
* Macros::
* Escapes::


File: groff.info,  Node: Requests,  Next: Macros,  Prev: Embedded Commands,  Up: Embedded Commands

Requests
--------

   A request line begins with a control character, which is either a
single quote (`'') or a period (`.').  These can be changed, see *Note
Character Translations::, for details.  After this, there may be
optional tabs or spaces followed by an identifier which is the name of
the request.  This may be followed by any number of space separated
arguments.

   If you want to begin a line with a control character without it being
interpreted, precede it with a `\&'.  This represents a zero width
space, which means it will not affect you output.

   In most cases you will use the period as a control character.
Several requests will cause a break, using the single quote control
character will prevent this.

* Menu:

* Request Arguments::


File: groff.info,  Node: Request Arguments,  Prev: Requests,  Up: Requests

Request Arguments
.................

   Argument to requests (and macros) are processed much like the shell:
The line is split into arguments according to spaces.  An argument
which is intended to contain spaces can either be enclosed in quotes
(single or double), or have the spaces "escaped" with backslashes.

   Let's look at some examples:

     .uh The Mouse Problem
     .uh "The Mouse Problem"
     .uh The\ Mouse\ Problem

The first line is the `.uh' macro being called with 3 arguments, `The',
`Mouse', and `Problem'.  The latter two have the same effect or calling
the `.uh' macro with a single argument `The Mouse Problem'.

   Note, however, that the `.ds' request works differently.

   *Note Strings::.


File: groff.info,  Node: Macros,  Next: Escapes,  Prev: Requests,  Up: Embedded Commands

Macros
------

   Troff has a "macro" facility for defining a series of lines which
can be invoked by name.  They are called in the same manner as requests,
and arguments may be passed in the same manner.

   *Note Writing Macros::.  *Note Request Arguments::.


File: groff.info,  Node: Escapes,  Prev: Macros,  Up: Embedded Commands

Escapes
-------

   Escapes may occur anywhere in the input to `groff'.  They begin with
a backslash and are followed by a single character which indicates the
function to be performed.

   Many escapes have no parameters; those that do, do so in one of two
ways.  For escapes which require an identifier there must be a way for
`groff' to tell where the identifier ends and the text begins.  It
assumes that the next single character is the identifier, but if that
character is an open parenthesis, it takes the next two characters as
the identifier; and if the next character is an open bracket, all
characters until a close bracket are taken as the identifier.  Note
that in the second case there is no closing parenthesis.  For example:

     \fB
     \n(XX
     \*[TeX]

   Other escapes may require several arguments and/or some special
format.  In these cases the "argument" is enclosed in single quotes
(not required??) and the enclosing text is decoded according to what
that escape expects.

     \l'1.5i\(bu'

   If you want to have a backslash appear in your output, you can use
several escapes: `\\', `\e' or `\E'.  These are very similar, and only
differ with respect to being used in macros or diversions (*Note
Copy-in Mode::, and *Note Diversions::, for more information).

   *Note Identifiers::.

* Menu:

* Comments::


File: groff.info,  Node: Comments,  Prev: Escapes,  Up: Escapes

Comments
........

   Probably one of the most(1) (*note Comments-Footnote-1::) common
forms of escapes is the comment.  Comments begin with the `\"' escape
and end at the end of the input line.

   This may sound simple, but it can be tricky to keep the comments from
interfering with the apperarance of your final outupt.

   If the escape is to the right of some text or a request, that portion
of the line will be ignored, but the space leading up to it will be
noticed by groff.  This only affects the `.ds' request (any others?).

   One possibly irritating idiosyncracy is that you mustn't use tabs to
line up your comments.  Tabs are not treated as white space between
request and macro arguments.

   If you have a comment on a line by itself, it will be treated as a
blank line, because after eliminating the comment, that is all that
remains.  So, it is common to start the line with `.\"' which will
cause the line to be treated as an undefined request.

   Another commenting scheme seen sometimes is three consecutive single
quotes (`'''') at the begining of a line.  This works, but `groff' will
give a warning about an undefined macro, which is harmless, but
irritating.

   To avoid problems with traditional comment styles, `groff' has a new
comment mechanism using the `\#' escape.  This escape works the same as
`\"' except that the newline is also ignored.

   For commenting-out large blocks of text, the `ig' request may be
useful; it causes `groff' to ignore the entire block until the line
with a lone `..'.  *Note Strings::.


File: groff.info,  Node: Comments-Footnotes,  Up: Comments

   (1) Unfortunately, this is a lie.  But hopefully future `troff'
hackers will believe it `:-)'.


File: groff.info,  Node: Registers,  Next: Manipulating Filling and Adjusting,  Prev: Embedded Commands,  Up: Programming Tutorial

Registers
=========

   Registers are `groff''s numeric variables.  `groff' has a number of
builtin registers, supplying anything from the date to details of
formatting parameters.

   *Note Identifiers::.

* Menu:

* Setting Registers::
* Interpolating Registers::
* Auto-increment::
* Assigning Formats::
* Builtin Registers::


File: groff.info,  Node: Setting Registers,  Next: Interpolating Registers,  Prev: Registers,  Up: Registers

Setting Registers
-----------------

   Registers are defined/set via the `nr' request or the `\R' escape,
for example, the following two lines are equivalent:

     .nr a 1
     \R'a 1'

   The `rr' request will remove the register specified by the argument.

   The `rnn' request will rename a number register.  The format is
`.rnn X Y', which will rename number register  X to Y.

   Aliases can be created for a number register.  The format is `.aln
XX YY', which will create an alias XX for number register object named
YY.  The new name and the old name will be exactly equivalent.  If YY
is undefined, a warning of type `reg' will be generated, and the
request will be ignored.  *Note Debugging::, for information about
warnings.


File: groff.info,  Node: Interpolating Registers,  Next: Auto-increment,  Prev: Setting Registers,  Up: Registers

Interpolating Registers
-----------------------

   Numeric registers are "interpolated" via the `\n' escape.

     .nr as \na+\na
     \n(as


File: groff.info,  Node: Auto-increment,  Next: Assigning Formats,  Prev: Interpolating Registers,  Up: Registers

Auto-increment
--------------

   Number registers can also be auto incremented/decremented.  You can
specify the increment/decrement factor with third argument to the `nr'
request.  The default value is 0.  For example:

     .nr a 0 1
     .nr xx 0 5
     \n+a, \n+a, \n+a, \n+a, \n+a
     .br
     \n+(xx, \n+(xx, \n+(xx, \n+(xx, \n+(xx

produces:

     1, 2, 3, 4, 5
     5, 10, 15, 20, 25

   If you want to change the increment factor without changing the value
of a register, the following can be used:

     .nr a \na 10


File: groff.info,  Node: Assigning Formats,  Next: Builtin Registers,  Prev: Auto-increment,  Up: Registers

Assigning Formats
-----------------

   When a register is used in the text of an input file (as opposed to
part of an expression), it is textually replaced (or interpolated) with
a representation of that number.  This output format can be changed to
a variety of formats (numbers, roman numerals, etc.).  This is done
using the `af' request.  The first argument to `af' is the name of the
number register to be changed, and the second argument is the output
format.  The following output formats are available:

`1'
     This is the default format, decimal numbers: 1, 2, 3, ...

`001'
     Decimal numbers with as many leading zeros as specified.  So,
     `001' would result in 001, 002, 003, ...

`I'
     Upper-case roman numerals: 0, I, II, III, IV, ...

`i'
     Lower-case roman numerals: 0, i, ii, iii, iv, ...

`A'
     Upper-case letters: A, B, C, ..., Z, AA, AB, ...

`a'
     Lower-case letters: a, b, c, ..., z, aa, ab, ...

   The following example will produce `10, X, j, 010'.

     .nr a 10
     .af a 1           \" the default format
     \na,
     .af a I
     \na,
     .af a a
     \na,
     .af a 001
     \na

   The `\g' escape returns the current format of the specified
register.  For example, `\ga' after the following example would produce
`001'.


File: groff.info,  Node: Builtin Registers,  Prev: Assigning Formats,  Up: Registers

Builtin Registers
-----------------

   The following are some built-in registers, which are not listed
elsewhere in this manual.  Any registers which begin with a `.' are
read-only.  A complete listing of all built-in registers can be found
in *Note Register Index::.

`.H'
     Horizontal resolution in basic units.

`.V'
     Vertical resolution in basic units.

`dw'
     Day of the week (1-7).

`dy'
     Day of the year (1-31).

`mo'
     Current month (1-12).

`yr'
     Last two digits of the current year (see you after year 2000 :-)

`.c'
`c.'
     The current _input_ line number.

`ln'
     The current _output_ line number.

`.x'
     The  major  version  number.  For example, if the version number
     is 1.03 then `.x' will contain 1.

`.y'
     The minor version number.  For example, if the version number is
     1.03 then `.y' will contain 03.

`.g'
     Always 1.  Macros should use this to determine whether they are
     running under GNU `troff'.

`.A'
     If the current output device is ASCII, this is set to 1, zero
     otherwise.

`.P'
     This register indicates whether the current page is actualy being
     printed, i.e. if the `-o' option is being used to only print
     selected pages.  *Note Options::, for more information.


File: groff.info,  Node: Manipulating Filling and Adjusting,  Next: Manipulating Hyphenation,  Prev: Registers,  Up: Programming Tutorial

Manipulating Filling and Adjusting
==================================

   Several ways of causing "breaks" were given in *Note Implicit Line
Breaks::.  The `br' request will likewise cause a break.  Several other
requests will also cause breaks, implicitly.  They are: `bp', `ce',
`fi', `fl', `in', `nf', `sp' and `ti'.

   Initially, groff will fill and ajust text to both margins.  Filling
can be disabled via the `nf' request and re-enabled with the `fi'
request.  These implicitly disable and re-enable adjusting.  Both of
these will cause break in text currently being filled.  The number
register `.u' is equal to 1 in fill mode and 0 in no-fill mode.

   Adjusting can be disabled with the `ad' request and re-enabled with
the `na' request.  The `ad' request takes a single argument to indicate
how to adjust text.  The current adjustment mode is available in the
number register `.j':

`l'
     Adjust text to the left margin.  This produces what is
     traditionally called ragged-right text.

`r'
     Adjust text to the right margin.

`c'
     Center filled text.

`b'
`n'
     Justify to both margins.  This is `groff''s default.

   With no argument to `ad', `troff' will adjust lines the same way it
was the last time it was filling.  For example:

     text
     .ad r
     text
     .ad c
     text
     .na
     text
     .ad  \" back to centering
     text

   The escape `\p' will cause a break and cause the remaining text to
be adjusted.

   The `ss' request allows you to change the minimum size of a space
between filled words.  This request takes its units as one twelfth of
the spacewidth parameter for the current font.  Initially both the word
space size and the sentence space size are 12.

   When two arguments are given to the `ss' request, the second argument
gives the sentence space size. If the second argument is not given, the
sentence space size will be the same as the word space size.  The
sentence space size is used in two circumstances: if the end of a
sentence occurs at the end of a line in fill mode, then both an
inter-word space and a sentence space will be added; if two spaces
follow the end of a sentence in the middle of a line, then the second
space will be a sentence space.  Note that the behaviour of UNIX
`troff' will be exactly that exhibited by GNU `troff' if a second
argument is never given to the `ss' request. In GNU troff, as in UNIX
`troff', you should always follow a sentence with either a newline or
two spaces.

   The number registers `.ss' and `.sss' hold the values of the
parameters set by the first and second arguments of the `ss' request.

   The `ce' request will center text.  While the `.ad c' request will
also center text, it has the side effect of filling the text.  The `ce'
request will not fill the text it affects.  This request causes a break.

   With no arguments, `ce' will fill the next line of text.  The single
argument `ce' takes is a number indicating the number of lines to be
centered.  With no argument centering is disabled.

   A common idiom is to turn on centering for a large number of lines,
and then turn off centering when you are done with the centered text.
This is useful for any request which takes a number of lines as an
argument.

     .ce 1000
     replace this
     with
     something
     more interesting
     ...
     .ce 0

   The `.ce' number register contains the number of lines remaining to
be centered, as set by the `ce' request.

   A similar request is `rj' request which will justify unfilled text
to the right margin.  Its arguments are identical to the `ce' request.
The `.rj' number register is the number of lines to be right-justified
as set by the `rj' request.


File: groff.info,  Node: Manipulating Hyphenation,  Next: Manipulating Spacing,  Prev: Manipulating Filling and Adjusting,  Up: Programming Tutorial

Manipulating Hyphenation
========================

   As discussed in *Note Hyphenation::, `groff' will hyphenate words.
There are a number of ways to modify the how hyphenation is done.

   This hyphenation can be turned off with the `nh' request, and turned
back on with the `hy' request.  However, `troff''s hyphenation
facilities are far more flexible than this.  The `hy' request can be
used to tell `troff' to restrict hypenation to certain cases.  The
request takes a single numeric argument.  The current hyphenation
restrictions can be found in the number register `.hy'

`1'
     The default argument, which indicates to hyphenate without
     restrictions.

`2'
     Do not hyphenate the last word on a page or column.

`4'
     Do not hyphenate the last two characters of a word.

`8'
     Do not hyphenate the first two characters of a word.

   The `hlm' request will set the maximum number of consecutive
hyphenated lines to the value given as the first argument.  If this
number is negative, there is no maximum.  The default value is -1.
This value is associated with the current environment.  Only lines
output from an environment count towards the maximum associated with
that environment.  Hyphens resulting from `\%' are counted; explicit
hyphens are not.  The current setting of this is available in the
`.hlm' request.  Also the number of immediately preceding consecutive
hyphenated lines are available in the number register `.hlc'.

   The `hw' request allows you to specify how a specific word is to be
hyphenated.  It takes only one argument which is the word with hyphens
at the hyphenation points.  For example: `.hw in-sa-lub-rious'.

   You can also tell `troff' how to hyphenate words on the fly with the
use of the `\%' escape, also known as the "hyphenation character".
Preceding a word with this character will prevent it from being
hyphenated, putting it in a word will indicate to `troff' that the word
may be hyphenated at that point.  Note that this mechanism will only
affect one word, if you want to change the hyphenation of a word for
the entire document, use the `hw' request.

   The `hc' request allows you to change the hyphenation character.
The character specified as an argument will then work the same as the
`\%' escape, and, thus, no longer appear in the output.  Without an
argument it will return the hyphenation character to `\%'.

   To further customize hyphenation the `hpf' request will read in a
file of hyphenation patterns.  This file will be searched for in the
same way that `tmac.NAME' is searched for when the `-mNAME' option is
specified.

   It should have the same format as the argument to the \patterns
primitive in TeX; the letters appearing in this file are interpreted as
hyphenation codes.  A `%' character in the patterns file introduces a
comment that continues to the end of the line.

   The set of hyphenation patterns is associated with the current
language set by the `hla' request.  The `hpf' request is usually
invoked by the `troffrc' file.

   The request `.hcode C1 CODE1 C2 CODE2...' sets the hyphenation code
of character C1 to CODE1, that of C2 to CODE2, etc.  A hyphenation code
must be a single input character (not a special character) other than a
digit or a space.  Initially each lower-case letter has its hyphenation
code set to itself, and each upper-case letter has a hyphenation code
which is the lower case version of itself.

   The `hym' request will set the hyphenation margin to the value given
as the first argument: when the current adjustment mode is not `b', the
line will not be hyphenated if the line is no more than that amount
short.  The default hyphenation margin is 0.  The default scaling
indicator for this request is m.  The hyphenation margin is associated
with the current environment.  The current hyphenation margin is
available in the `.hym' register.

   The `hys' request set the hyphenation space to the value given as
the first argument: when the current adjustment mode is `b', don't
hyphenate the line if the line can be justified by adding no more than
that amount of extra space to each word space.  The default hyphenation
space is 0.  The default scaling indicator for this request is `m'.
The hyphenation space is associated with the current environment.  The
current hyphenation space is available in the `.hys' register.

   The `shc' request will set the soft hyphen character to the argument
given as an argument.  If the argument is omitted, the soft hyphen
character will be set to the default `\(hy'. The soft hyphen character
is the character which will be inserted when a word is hyphenated at a
line break.  If the soft hyphen character does not exist in the font of
the character immediately preceding a potential break point, then the
line will not be broken at that point.  Neither definitions (specified
with the `char' request) nor translations (specified with the `tr'
request) are considered when finding the soft hyphen character.

   The `hla' request will set the current hyphenation language to that
given by the first argument.  Hyphenation exceptions specified with the
`hw' request and hyphenation patterns specified with the `hpf' request
are both associated with the current hyphenation language.  The `hla'
request is usually invoked by the `troffrc' file.  The current
hyphenation language is available in the number register `.hla'.


File: groff.info,  Node: Manipulating Spacing,  Next: Tabs and Fields,  Prev: Manipulating Hyphenation,  Up: Programming Tutorial

Manipulating Spacing
====================

   The `sp' request will cause `troff' to space downwards the distance
specified as the first argument.  With no argument it will advance 1
line.  A negative argument will cause `troff' to move up the page the
specified distance.  If the argument is preceded by a `|' `troff' will
move that distance from the top of the page.

   Often you may want your output to be double or triple spaced.  The
`ls' request will cause `troff' to output N-1 blank lines after each
line of text, where N is the argument given to the `ls' request.  With
no argument `troff' will go back to single spacing.  The number
register `.L' contains the current line spacing setting.

   Sometimes, extra vertical spacing is only needed occasionaly, i.e.
to allow space for a tall construct (like an equation).  The `\x'
escape will do this.  The escape is given a numerical argument (like
`\x'3p'').  If this number is positive extra vertical space will be
inserted below the current line.  A negative number will add space
above.  If this escape is used multiple times on the same line, the
maximum values are used.  The `.a' number register contains the most
recent extra vertical *emph* line space.

   Spacing (via either `sp' or via blank lines) can be disabled with
the `ns' request.  This will enable "no-space mode".  This mode will
end when actual text is output or the `rs' request is encountered.
No-space mode will also prevent requests to advance to the next page
unless they are accompanied by a page number (see *Note Page Control::,
for more information.)


File: groff.info,  Node: Tabs and Fields,  Next: Character Translations,  Prev: Manipulating Spacing,  Up: Programming Tutorial

Tabs and Fields
===============

   Tab stops are much like those on a typewriter: a tab character (or
the `\t' escape) on input will cause horizontal motion to the next tab
stop.

   Tab stops can be changed with the `ta' request.  This request takes
a series of numbers as arguments which indicate where each tab stop is
to be (overriding any previous settings).  These can be specified
absolutely, i.e. as the distance from the left margin.  For example,
the following wil set tab stops every one inch.

     .ta 1i 2i 3i 4i 5i 6i

   Tab stops can also be specified relatively (using a leading `+')
which means that the specified tab stop will be set that distance from
the previous tab stop.  For example the following is equivalent to the
previous example.

     .ta 1i +1i +1i +1i +1i +1i

   After the specified tab stops repeat values may be set for tabs
beyond the last one specified.  This is most commonly used to specify
tabs set at equal intervals.  The complete syntax for setting tabs is
`.ta N1 N2 ... NN T R1 R2 ... RN'.  This will set tabs at positions N1,
N2, ..., NN and then set tabs at NN+R1, NN+R2, ..., NN+RN and then at
NN+RN+R1, NN+RN+R2, ..., NN+RN+RN, and so on.  For example the
following is, yet again, the same as the previous examples.

     .ta T 1i

   The material in each tab column may be justified to the right or left
or centered in the column.  This is specified by appending an `R', `L'
or `C' to the number specifying that tab stop:

     .ta 1i 2iC 2iR

   The default justification is `L'.

   The number register `.tabs' contains a string representation of the
current tab settings suitable for use as an argument to the `ta'
request.

   Normally `troff' will fill the space to the next tab stop with
spaces.  In some cases you may wish to change this.  The `tc' request
will do this.  With no argument `troff' will revert to using spaces.

Leaders
-------

   Sometimes you may wish to use the `tc' request to fill a tab stop
with a given character, but also, you want to use normal tab stops on
the rest of the line.  For this `groff' provides an alternate tab
mechanism, called "leaders" which will do just that.  They are used
exclusively to produce a repeated run of characters to the next tab
stop.

   You can declare what character will be repeated with the `lc'
request.  If you do not give it an argument, the leaders will act the
same as tabs.

   The difference is that a leader is invoked by using the `\a' escape.

   So for a table of contents you may want to have tab stops defined so
that the section number is one tab stop, the title is the second with
the remaining space being filled with a line of dots and then the page
number slightly separated from the dots.

     .lc .
     .ta .5iR 5i +.25i
     1.1\tFoo\a\t12

Fields
------

   Fields are a more general way of laying out tabular data.  `fc'


File: groff.info,  Node: Character Translations,  Next: Line Layout,  Prev: Tabs and Fields,  Up: Programming Tutorial

Character Translations
======================

   The control character (`.') and the no-break control character (`'')
can be changed with the `cc' and `c2' requests, respectively.  The
single argument is the new character to be used, with no argument the
normal control character is restored.

   The `eo' request will completely disable the escape mechanism.  The
`ec' request can be used to change the escape character from the
default `\' to what is specified as an argument.

   The `tr' request will translate characters.

   `trnt' This is the same as the `tr' request except that the
translations do not apply to text that is transparently throughput into
a diversion with `\!'.  *Note Diversions::, for more information.  For
example,

     .tr ab
     .di x
     \!.tm a
     .di
     .x

will print `b'; if `trnt' is used instead of `tr' it will print `a'.


File: groff.info,  Node: Line Layout,  Next: Page Layout,  Prev: Character Translations,  Up: Programming Tutorial

Line Layout
===========

   The following drawing shows the dimensions which `troff' uses for
placing a line of output onto the page.  They are labeled with the
requests which manipulate each dimension.

                   | -->| in |<--                   |
                -->| po |<-----------ll------------>|
                   +----+----+----------------------+----+
                   |    :    :                      :    |
                   +----+----+----------------------+----+

   These dimensions are:

`po'
     "Page offset"-this is the leftmost postition of text on the final
     output.  This can be adjusted with the `po' request, and the
     current setting can be found in the builtin number register `.o'
     Note that this request does not cause a break, so changing the page
     offset in the middle of text being filled may not do what you
     expect.

`in'
     "Indentation"-this is the distance from the left margin where text
     will be printed.  This can be adjusted with the `in' request, and
     the current setting can be found in the builtin number register.
     `.i' This request causes a break.

     There is also the request `ti' which will cause one output line to
     be indented, after which the indentation returns to 0.  This
     request causes a break.  The number register `.in' is the indent
     that applies to the current output line.

`ll'
     "Line length"-this is the distance from the left margin to right
     margin.  This can be adjusted with the `ll' request, and the
     current setting can be found in the builtin number register `.l'
     Note, as the figure implies, line length is not affected by the
     current indentation.  The number register `.ll' is the line length
     that applies to the current output line.

     .in +.5i
     .ll -.5i
     A bunch of really boring text which should
     be indented from both margins.
     replace me with a better (and more) example!
     .in -.5i
     .ll +.5i


File: groff.info,  Node: Page Layout,  Next: Page Control,  Prev: Line Layout,  Up: Programming Tutorial

Page Layout
===========

   Troff provides some very primitive operations for controlling page
layout.

   Troff lets you specify the "page length" via the `pl' request.  This
is the length of the physical output page.  The current setting can be
found in the builtin number register `.p'.  Note that this only
specifies the size of the page, not the top and bottom margins.  Those
are not done by `groff' directly; see *Note Traps::, for further
information on how to do this.

   Troff provides several operations which help in setting up top and
bottom titles (or headers and footers).

   The `tl' request will print a "title line", which consists of three
parts: a left justified portion, a centered portion and a right
justified portion.  The argument to `tl' is specified as
`'LEFT'CENTER'RIGHT'' The `%' character is replaced with the current
page number.

   The title line is printed using its own line length, which is
specified with the `lt' request.  The current setting of this is
available in the `.lt' number register.

   The `pn' request will change the page number of the _next_ page.
The only argument is the page number.

   The current page number is stored in the number register `%'.  The
number register `.pn' contains the number of the next page: either the
value set by a `pn' request, or the number of the current page plus 1.

   The `pc' request will change the page number character (used by the
`tl' request) to a different character.  With no argument, this
mechanism is disabled.

   *Note Traps::.


File: groff.info,  Node: Page Control,  Next: Fonts,  Prev: Page Layout,  Up: Programming Tutorial

Page Control
============

   To stop processing the current page, and move to the next page, you
can invoke the `bp' request.  This request will also cause a break.
This request can also take an argument of what the next page should be
numbered.  The only difference between `bp' and `pn' is that `pn' does
not cause a break or actually eject a page.

     .de newpage
     'bp
     'sp .5i
     .tl 'left top'center top'right top'
     'sp .3i
     ..

   Often you may want to make sure that you have a certain amount of
space before a new page occurs.  This is most useful to make sure that
there is not a single "orphan" line left at the bottom of a page.  The
`ne' request will ensure that there is a certain distance, specified by
the first argument, before the next page is triggered (see *Note
Traps::, for further information).  The default unit for `ne' is v's
and the default argument is 1v.

   For example, to make sure that no fewer than 2 lines get orphaned,
you can do the following before each paragraph.

     .ne 2
     .ti +5n
     text

   The `sv' is similar to the `ne' request, it reserves the specified
amount of vertical space.  If the desired amount of space exists before
the next trap (bottom page boundary), the space will be output
immediately.  If there is not enough space, it is stored for later
output via the `os' request.  The default argument is 1v and the
default units are v's.


File: groff.info,  Node: Fonts,  Next: Sizes,  Prev: Page Control,  Up: Programming Tutorial

Fonts
=====

   Groff gives you the ability to switch fonts at any point in your
text.  There are two ways to do this, via the `ft' request and the `\f'
escape.

   Fonts are generaly specified as uppercase strings, which are usually
1 to 4 characters representing an abreviation of acronym of the font
name.

   The basic set of fonts are R, I, B, and BI.  These are Times Roman,
Italic, Bold, and Bold Italic.  There is also at least one symbol font
which contains various special symbols (greek, mathematics).  These
latter fonts cannot be used directly, but should be used via an escape.

* Menu:

* Changing Fonts::
* Font Families::
* Font Positions::
* Using Symbols::
* Artificial Fonts::
* Ligatures and Kerning::


File: groff.info,  Node: Changing Fonts,  Next: Font Families,  Prev: Fonts,  Up: Fonts

Changing Fonts
--------------

   You can change fonts with both the `ft' request.  With no arguments,
it will switch to the previous font (also known as P).

     eggs, bacon,
     .ft B
     spam
     .ft
     and sausage.

   The `\f' escape is useful for changing fonts in the middle of words.

     eggs, bacon, \fBspam\fP and sausage.

   Both of the above examples will produce the same output.

   Sometimes, when putting letters of different fonts, you need more or
less space at such boundaries.  There are two escapes to help with this.

   The `\/' escape increases the width of the preceding character so
that the spacing between that character and the following character
will be correct if the following character is a roman character.  For
example, if an italic f is immediately followed by a roman right
parenthesis,  then in many fonts the top right portion of the f will
overlap the top left of the right parenthesis.  It is a good idea to
use this escape sequence whenever an italic character is immediately
followed by a roman character without any intervening space.

   The `\,' escape modifies the spacing of the following character so
that the spacing between that character and the preceding character
will correct if the preceding character is a roman character.  It is a
good idea to use this escape sequence whenever a roman character is
immediately followed by an italic character without any intervening
space.

   The `ftr' request will translate fonts, it is called as `.ftr F G',
which Translate font F to G.  Whenever a font named F is referred to in
`\f' escape sequence, or in the `ft', UL, BD, CS, TKF, SPECIAL,
FSPECIAL, FP, or STY requests, font G will be used.  If G is missing,
or equal to F then font F will not be translated.


File: groff.info,  Node: Font Families,  Next: Font Positions,  Prev: Changing Fonts,  Up: Fonts

Font Families
-------------

   Due to the variety of fonts available, `groff' has added the concept
of font families.  Each of these families has four styles (R, I, B and
BI),

   The fonts are specified as the concatenation of the font family and
style.  Specifying a font without the family part will cause `groff' to
use that style of the current family.  By default, `groff' uses the
Times family.

   This way, you can just use the basic four fonts and select a
different font family on the command line.

   You can also switch font families with the `fam' request The current
font family is available in the number register `.fam'.  This is a
string-valued register.

     spam,
     .fam H
     spam,
     .ft B
     spam,
     .fam T
     spam,
     .ft AR
     baked beans,
     .ft R
     and spam.


File: groff.info,  Node: Font Positions,  Next: Using Symbols,  Prev: Font Families,  Up: Fonts

Font Positions
--------------

   For the sake of old phototypesetters and compatability with old
versions of `troff', `groff' has the concept of font "positions", on
which various fonts are mounted.  The last one or two are reserved for
the symbol font(s).

   New fonts can be mounted with the `fp' request.  These numeric
positions can then be referred to with font changing commands.  When
`groff' starts it is using font number one.

     .fp 1 H
     .fp 2 HI
     .fp 3 HB
     wink, wink,
     .ft 2
     nudge, nudge,
     .ft
     .ft 3
     say no more!
     .ft

(note that after these font changes have taken place, the original font
is restored.)

   The current font in use, as a font position.  This can be useful to
remember the current font, for later recall.

     .nr save-font \n(.f
     ... lots 'o text ...
     .ft \n[save-font]

   The number of the next free font position is available in the number
register `.fp'.  This is useful when mounting a new font, like so:

     .fp \n[.fp] NEATOFONT

   Fonts not listed in the `DESC' file are automatically mounted on the
next available font position when they are referenced.  If a font is to
be mountfed explicitly with the `fp' request on an unused font
position, it should be mounted on the first unused font position, which
can be found in the `.fp' register; although `troff' does not enforce
this strictly, it will not allow a font to be mounted at a position
whose number is much greater than that of any currently used position.

   The `fp' request has an optional third argument.  This argument
gives the external name of the font, which is used for finding the font
description file.  The second argument gives the internal name of the
font which is used to refer to the font in `troff' after it has been
mounted.  If there is no third argument then the internal name will be
used as the external name.  This feature allows you to use fonts with
long names in compatibility mode.


File: groff.info,  Node: Using Symbols,  Next: Artificial Fonts,  Prev: Font Positions,  Up: Fonts

Using Symbols
-------------

   Symbols can be inserted by using a special escape sequence.  This
escape is simply the escape character (a backslash) followed by an
identifier.  The symbol identifiers have to be two or more characters,
since single characters conflict with all the other escapes.  The
identifier can be either preceded by a parenthesis if it is two
character, or surrounded by square brackets.  So, the symbol for pi can
be produced either by `\(*p' or `\[*p]'.

     area = \(*p\fIr\fP\u2\d

   The escape `\C'XXX'' will typeset character named XXX.  Normally it
is more convenient to use `\[XXX]'.  But `\C' has the advantage that it
is compatible with recent versions of `ditroff' and is available in
compatibility mode.

   The escape `\N'N'' will typeset the character with code N in the
current font.  N can be any integer.  Most devices only have characters
with codes between 0 and 255.  If the current font does not contain a
character with that code, special fonts will not be searched.  The `\N'
escape sequence can be conveniently used on conjunction with the `char'
request:

     .char \[phone] \f(ZD\N'37'

   The code of each character is given in the fourth column in the font
description file after the charset command.  It is possible to include
unnamed characters in the font description file by using a name of
`---'; the `\N' escape sequence is the only way to use these.

   Each character has certain properties associated with it.  These
properties can be modified with the `cflags' request.  The first
argument is the the sum of the desired flags and the remaining
arguments are the characters to have those properties.
`1'
     the character ends sentences (initially characters `.?!' have this
     property);

`2'
     lines can be broken before the character (initially no characters
     have this property);

`4'
     lines can be broken after the character (initially characters
     `-\(hy\(em' have this property);

`8'
     the character overlaps horizontally (initially characters
     `\(ul\(rn\(ru' have this property);

`16'
     the character overlaps vertically (initially character `\(br' has
     this property);

`32'
     an end of sentence character followed by any number of characters
     with this property will be treated as the end of a sentence if
     followed by a newline or two spaces; in other words the character
     is transparent for the purposes of end of sentence recognition;
     this is the same as having a zero space factor in TeX (initially
     characters `"')]*\(dg\(rq' have this property).

   You can create new characters with the `char' request.  It is called
as `.char C STRING', and defines character C to be STRING. Every time
character C needs to be printed, STRING will be processed in a
temporary environment and the result will be wrapped up into a single
object.  Compatibility mode will be turned off and the escape character
will be set to `\' while STRING is being processed.  Any emboldening,
constant spacing or track kerning will be applied to this object rather
than to individual characters in STRING.  A character defined by this
request can be used just like a normal character provided by the output
device.  In particular other characters can be translated to it with the
`tr' request; it can be made the leader character by the `lc' request;
repeated patterns can be drawn with the character using the `\l' and
`\L' escape sequences;  words containing the character can be
hyphenated correctly, if the `hcode' request is used to give the
character a hyphenation code. There is a special anti-recursion
feature: use of character within the character's definition will be
handled like normal characters not defined with `char'.

   A character definition can be removed with the `rchar' request.  Its
arguments are the characters to be removed.  This undoes the effect of
a `char' request.


File: groff.info,  Node: Artificial Fonts,  Next: Ligatures and Kerning,  Prev: Using Symbols,  Up: Fonts

Artificial Fonts
----------------

   There are a number of requests for artificially creating fonts.
These are largely vestigal remains from the days when output devices
did not have a wide variety of fonts, and when `nroff' and `troff' were
separate programs.  These are no longer necessary in GNU Troff.

   The `ul' request will print subsequent lines in italics on a device
capable of it, or underline the text on an ASCII output device.  The
single argument is the number of lines to be "underlined," with no
argument, the next line will be underlined.

   The `cu' request is similar to `ul' ...

   The `uf' request will set the underline font used by `ul' and `cu'.

   The `bd' request artificially creates a bold font by printing each
character twice, slightly offset.  The first argument specifies the
font to embolden, and the second is the number of basic units, minus
one, by which the two characters will be offset.  If the second
argument is missing, emboldening will be turned off.


File: groff.info,  Node: Ligatures and Kerning,  Prev: Artificial Fonts,  Up: Fonts

Ligatures and Kerning
---------------------

   `lg' `.lg' The current ligature mode.

   If the font description file contains pairwise kerning information,
characters from that font will be kerned.  Kerning between two
characters can be inhibited by placing a `\&' between them.

   `kern' enables pairwise kerning if n is non-zero or missing,
otherwise it disables pairwise kerning.  The register `.kern' holds the
value of 1 if pairwise kerning is enabled, 0 otherwise.

   The request `.tkf F S1 N1 S2 N2' enable track kerning for font F.
When the current font is F, the width of every character will be
increased by an amount between N1 and N2: when the current point size
is less than or equal to S1, the width will be increased by N1; when it
is greater than or equal to S2 the width will be increased by N2; when
the point size is greater than or equal to S1 and less than or equal to
S2 the increase in width is a linear function of the point size.


File: groff.info,  Node: Sizes,  Next: Strings,  Prev: Fonts,  Up: Programming Tutorial

Sizes
=====

   Groff uses two dimensions with each line of text, type size and
vertical spacing.  The type size is the height from the text "baseline"
to the top of the tallest character (decenders may drop below this
baseline).  Vertical spacing is the amount of space `groff' allows for
a line of text, normally, this is about 20% larger than the current
type size.  Ratios smaller than this can result in hard-to-read text,
larger that this, it will spread your text out more vertically (useful
for term papers).  By default, `troff' uses 10 point type on 12 point
spacing.

   The difference between type size and vertical spacing is known, by
typesetters, as "leading".

* Menu:

* Changing Type Sizes::
* Fractional Type Sizes::


File: groff.info,  Node: Changing Type Sizes,  Next: Fractional Type Sizes,  Prev: Sizes,  Up: Sizes

Changing Type Sizes
-------------------

   Using the `ps' request and the `\s' escape you can change the type
size.  The `vs' request will change the vertical spacing. The default
unit for the `ps' and `vs' requests are points.  The number registers
`.s' and `.v' contain the current type size and vertical spacing.

   These requests take parameters in units of points.  You can specify
sizes as an absolute size, or as a relative change from the current
size.  The size 0 means go back to the previous size.  With no argument
it will revert to the previous size.

     snap, snap,
     .ps +2
     grin, grin,
     .ps +2
     wink, wink, \s+2nudge, nudge,\s+8 say no more!
     .ps 10

   The `\s' escape may be called in a variety of ways.  Much like other
escapes there must be a way to determine where the argument ends and
the text begins.  Any of the following forms are valid: `\sN', `\s+N',
`\s-N', `\s(NN', `\s+(NN', `\s-(NN', `\s[+NNN]', `\s[-NNN]', `\s+[NNN]',
`\s-[NNN]'.

   Some devices may only have certain permissible sizes, in which case
`groff' will round to the nearest permissible size.


File: groff.info,  Node: Fractional Type Sizes,  Prev: Changing Type Sizes,  Up: Sizes

Fractional Type Sizes
---------------------

   A "scaled point" is equal to 1/SIZESCALE points, where SIZESCALE is
specified in the `DESC' file (1 by default.)  There is a new scale
indicator `z' which has the effect of multiplying by SIZESCALE.
Requests and escape sequences in `troff' interpret arguments that
represent a pointsize as being in units of scaled points, but they
evaluate each such argument using a default scale indicator of `z'.
Arguments treated in this way are the argument to the `ps' request, the
third argument to the `cs' request, the second and fourth arguments to
the `tkf' request, the argument to the `\H' escape sequence, and those
variants of the `\s' escape sequence that take a numeric expression as
their argument.

   For example, suppose SIZESCALE is 1000; then a scaled point will be
equivalent to a millipoint; the request `.ps 10.25' is equivalent to
`.ps 10.25z' and so sets the pointsize to 10250 scaled points, which is
equal to 10.25 points.

   The number register `\n(.s' returns the pointsize in points as
decimal fraction.  There is also a new number register `\n[.ps]' that
returns the pointsize in scaled points.

   It would make no sense to use the `z' scale indicator in a numeric
expression whose default scale indicator was neither `u' nor `z', and
so `troff' disallows this.  Similarily it would make no sense to use a
scaling indicator other than `z' or `u' in a numeric expression whose
default scale indicator was `z', and so `troff' disallows this as well.

   There is also new scale indicator `s' which multiplies by the number
of units in a scaled point.  So, for example, `\n[.ps]s' is equal to
1m.  Be sure not to confuse the `s' and `z' scale indicators.

   `\s'+N'' `\s'-N'' `\s+'N'' `\s-'N'': Set the point size to N scaled
points; N is a numeric expression with a default scale indicator of `z'.

   `\n[.ps]': The current pointsize in scaled points.

   `\n[.psr]': The last-requested pointsize in scaled points.

   `\n[.sr]': The last requested pointsize in points as a decimal
fraction.  This is a string-valued register.

   *Note Font Files::.


File: groff.info,  Node: Strings,  Next: Conditionals and Loops,  Prev: Sizes,  Up: Programming Tutorial

Strings
=======

   Groff has string variables, which are entirely for user convenience
(i.e. there are no built-in strings).  They are defined via the `ds'
request.

     .ds UX \s-1UNIX\s0\u\s-3tm\s0\d

   These are interpolated, or expanded in-place, via the `\*' escape:

     The \*(UX Operating System

will produce:

     The UNIXtm Operating System

   If the string named by the `\*' does not exist, the escape will be
replaced by nothing.

   NOTE:  Unlike other requests the third argument takes up the entire
line including trailing spaces.  This means that comments on a line
with such a request can introduce unwanted space into a string.

     .ds UX \s-1UNIX\s0\u\s-3tm\s0\d \" trademark of you-know-who

   Instead you should either put the comment on another line or have
the comment escape adjacent with the end of the string.

     .ds UX \s-1UNIX\s0\u\s-3tm\s0\d\"  trademark of you-know-who

   If you need leading space you can start the string with a double
quote.  No trailing quote is needed, in fact any trailing quote is
included in your string.

     .ds sign "           Yours in a white wine sauce,

   You can also append onto a string with the `as' request.  It works
the same as the `ds' request except that it appends the second argument
onto the string named by the first argument.

     .as sign " with shallots, onions and garlic,

   Strings are not limited to a sigle line of text.  A string can span
several lines by escaping the newlines with a backslash.  The resulting
string will be stored _without_ the newlines.

     .ds foo lots and lots \
     of text are on these \
     next several lines

   `rn'

   `rm'

   `chop'

   *Note Identifiers::.  *Note Comments::.


File: groff.info,  Node: Conditionals and Loops,  Next: Writing Macros,  Prev: Strings,  Up: Programming Tutorial

Conditionals and Loops
======================

   In `if' and `while' requests, there are several more operators
available:

`e'
`o'
     True if the current page is even or odd numbered (respectively)

`n'
`t'
     True if the document is being processed by `nroff' (or an ASCII
     device) or `troff'.

`'XXX'YYY''
     True if the string XXX is equal to the string YYY.  Other
     characters can be used in place of the single quotes.  The strings
     are "formatted" before being compared.

`rXXX'
     True if there is a number register named XXX.

`dXXX'
     True if there is a string, macro, diversion, or request named XXX.

`cCH'
     True if there is a character CH available;  CH is either an ASCII
     character or a special character `\(CH' or `\[CH]'; the condition
     will also be true if CH has been defined by the `char' request.

* Menu:

* if-else::
* while::


File: groff.info,  Node: if-else,  Next: while,  Prev: Conditionals and Loops,  Up: Conditionals and Loops

if-else
-------

   Troff has if-then-else constructs like other languages, although the
formatting can be painful.

   The `if' request is `troff''s if statement, it is called as `.if
EXPR ANYTHING', where EXPR is the expression to be evaluated, and
ANYTHING (the remainder of the line) which will be executed if EXPR
evaluates to non-zero (true).  ANYTHING will be interpreted as though
it was on a line by itself.  *Note Expressions::, for more info.

   Here are some examples:

     .if t .ls 2				\" double spacing in `troff'
     .if 0 .ab how'd this happen??

   An if-then-else is written using two requests `ie' and `el' the
first request is the if part and the latter is the else part.

     .ie
     .el

   In many cases you will want more than one request to be executed as a
result of any of these requests, this can be done using the \{ and \}
escapes.  The following example shows the possible ways to use these
escapes.

     .ie t \{\
     .    ds lq ``
     .    ds rq ''
     .\}
     .el \
     .\{\
     .    ds lq "
     .    ds rq "\}
     .ds qq "

   *Note Expressions::.


File: groff.info,  Node: while,  Prev: if-else,  Up: Conditionals and Loops

while
-----

   Groff provides a looping construct using the `while' request, which
is used much like the `if' (and related) requests.  The first argument
is an expression which will be evaluated.  The `while' request will
interpret the remainder of the line until the expression evaluates to 0
or false.

     .nr a 0 1
     .while (\na<9) \&\n+a,
     \&\n+a

   The preceding example produces:

     1, 2, 3, 4, 5, 6, 7, 8, 9, 10

   The `break' request will "break" out of a while loop.  Be sure not
to confuse this with the `.br' request.  The `continue' request will
finish the current iteration of a while loop.

   *Note Expressions::.


File: groff.info,  Node: Writing Macros,  Next: Page Motions,  Prev: Conditionals and Loops,  Up: Programming Tutorial

Writing Macros
==============

   A macro is a collection of text and embedded commands which can be
invoked multiple times.  Macros are used for defining common operations.
Macros are defined using the `de' request.  This request takes a name
for the macro as the first argument.  Subsequent lines are copied into
an internal buffer until the line `..' is encountered.  The optional
second argument to `de' can change this ending token.

   For example, suppose at the beginning of each paragraph, you want to
cause a break, move down a partial line and indent the first line.
Such a macro could be defined as follows:

     .de P
     .br
     .sp .8v
     ..

   The `am' request works similarily to `de' except it appends onto the
macro named by the first argument.  So, if we decide we want our
previously `P' macro to actually do indented instead of block
paragraphs we can add the necessary code to our existing macro.

     .am P
     .ti +5n
     ..

   Macros can be aliased with the `als' request.

* Menu:

* Copy-in Mode::
* Parameters::


File: groff.info,  Node: Copy-in Mode,  Next: Parameters,  Prev: Writing Macros,  Up: Writing Macros

Copy-in Mode
------------

   When `troff' reads in the test for a macro or diversion it copies the
text (including request lines) into an internal buffer, except for
escapes.  Escapes will be converted into an internal form, except for
`\n', `\$', `\*', `\\' and `\<RET>' which are evaluated and inserted
into the text where the escape was located.  This is known as "copy-in"
mode.

   What this means is that you can specify when these escapes are to be
evaluated (copy-in time or time of use) by insulating the escapes with
an extra backslash.

   For example, the following will result in the numbers 20 and 10 being
printed.

     .nr x 20
     .de y
     .nr x 10
     \&\nx
     \&\\nx
     ..
     .y


File: groff.info,  Node: Parameters,  Prev: Copy-in Mode,  Up: Writing Macros

Parameters
----------

   The arguments to a macro can be examined using a variety of escapes.
The number of arguments is available in the `.$' number register.  Any
individual argument can be retrieved with one of the following escapes:

   The escapes `\$N', `\$(NN' and `\$[NNN]' will result in the Nth,
NNth or NNNth argument.  Macros can have a unlimited number of
arguments.  Note that due to copy-in mode, you will want to have two
backslashes on these in actual use, since you do not want them
interpolated until the macro is actually invoked.

   The request `shift' will shift the arguments 1 position, or as many
positions as specified by the first argument.  After executing this
request, argument I will become argument I-N; arguments 1 to N will no
longer be available.  Shifting by negative amounts is currently
undefined.

   In some cases you will want to just use all of the arguments at once.
For example if you pass the arguments along to another macro.  The
`\$*' escape is the concatenation of all the arguments separated by
spaces.  A similar escape is `\$@', which is the concatenation of all
the arguments with each surrounded by double quotes, and separated by
spaces.

   The `\$0' escape is the name by which the current macro was invoked.
The `als' request can make a macro have more than one name.

     .de vl
     .ie \\n(.$=1 .ds Vl Pre-Release Version
     .el          .ds Vl Version \\$3, \\$4.
     ..

   This would be called as

     .vl $Id: groff.texinfo,v 1.5 1999/12/09 09:42:29 wlemb Exp $

   *Note Request Arguments::.


File: groff.info,  Node: Page Motions,  Next: Drawing Functions,  Prev: Writing Macros,  Up: Programming Tutorial

Page Motions
============

   Motions up and down the page can be done with the `sp' request.
However, this causes a break so that the actual effect is to move to
the left margin and then to the specified location.

   The request `mk' can be used to mark a location on a page, for
movement to later.  This request takes a register name as an argument
in which to store the current page location, with no argument it will
store the location in an internal register.  The results of this can be
used later by the `rt' or the `sp' request.  The `rt' request will
return *upwards* to the location given in the register name given as an
argument, with no argument it will return to the location marked with
the `mk' request

   There are escapes which will give you much finer control of movements
about the page.

   The `\v'E'' will let you do arbitrary vertical motion from the
current location on the page.  The argument E specifies the distance to
move, positive is downwards and negative upwards.  The default unit for
this escape is vertical spaces, `v''s.  Beware, however, that `troff'
will leave text processing to continue wherever the motion ends, so if
you don't want to interfere with text processing, make sure your
motions are balanced.

   There are some special case escapes for vertical motion.

`\r'
     move upwards 1v.

`\u'
     move upwards .5v.

`\d'
     move down .5v.

   Horizontal motions can be done via the `\h'E'' escape.  The
expression E indicates how far to move: positive is rightwards and
negative leftwards.

   There are a number of special case escapes for horizontal motion:

`\<SP>'
     An unbreakable and unpadable (i.e. not expanded during filling)
     space.  (Note: this is a backslash followed by a space.)

`\~'
     This produces an unbreakable space that stretches like a normal
     interword space when a line is adjusted.

`\|'
     a 1/6th em space.

`\^'
     a 1/12th em space.

`\0'
     a space the size of a digit.

`\&'
     A zero width space.

`\)'
     Like `\&' except that it behaves like a character declared with
     the `cflags' request to be transparent for the purposes of end of
     sentence recognition.

   Often you will want to do horizontal movement based on the width of
some arbitrary text (e.g. given as an argument to a macro).  For that,
there is the escape `\w'TEXT'' which will interpolate to the width of
the given TEXT in basic units.

   Font changes may occur in TEXT and not affect current settings.

   Also after use, `\w' sets several registers:

`st'
`sb'
     The highest and lowest point, respectively, in TEXT.

`rst'
`rsb'
     Like the `st' and `sb' registers, but takes account of the heights
     and depths of characters.

`ct'
     is set according to what kinds of characters occur in TEXT:
    0
          all short characters, no decenders or tall characters.

    1
          decender

    2
          tall character

    3
          both a decender and a tall character

`ssc'
     The amount of horizontal space (possibly negative) that should be
     added to the last character before a subscript.

`skw'
     How far to right of the center of the last character in the `\w'
     argument, the center of an accent from a roman font should  be
     placed over that character.

   `\k' `.k'


File: groff.info,  Node: Drawing Functions,  Next: Traps,  Prev: Page Motions,  Up: Programming Tutorial

Drawing Functions
=================

   Groff provides a number of ways to draw lines, and other figures on
the page.  Used in combination with the page motion commands (see *Note
Page Motions::, for more info) you can draw a wide variety of figures.
However, for complex drawings these operations can be quite cumbersome,
and it may be wise to use the pic preprocessor.

   All drawing is done via escapes.

   The `\l' will draw a line rightwards from the current location.  The
full syntax for this escape is `\l'LC'', where L is the length of the
line to be drawn, starting at the current location, positive numbers
will draw to the right, and negative will draw towards the left.  This
can also be specified absolutely (i.e. with a leading |) which will
draw back to the begining of the line.

   The optional second parameter C is a character to draw the line
with.  If this second argument is not specified, `troff' will use the
underscore character.

   If you need to separate the two arguments (to prevent `troff' from
interpreting a drawing character as a scaling indicator), you can
separate them with `\&'.

   And now, for a useful example:

     .de box
     \(br\\$*\(br\l'|0\(rn'\l'|0\(ul'
     ..

   Note that this works by outputing a box rule (a vertical line), then
the text given as an argument and then another box rule.  Then the line
drawing escapes both draw from the current location to the beginning of
the _input_ line.

   Vertical lines are drawn using the `\L' escape.  Its parameters are
specified the same as the `\l' escape.  If the length is positive, the
movement will be downwards, and upwards for negative.  The default
character is the box rule character.  As with the vertical motion
escapes, text processing will blindly continue where the line ends.

   More flexible drawing functions are available via the `\D' escape.
While the previous escapes will work on an ASCII device, these escapes
will not.

`\D'l X Y''
     Draw a line from the current location to the relative point
     specified by X, Y.

`\D'c D''
     Draw a circle with a diameter of D with the leftmost point at the
     current position.

`\D'C D''
     Draw a solid circle with the same parameters as an outlined circle.

`\D'e DX DY''
     Draw an ellipse with a horizontal diameter of DX and a vertical
     diameter of DY with the leftmost point at the current position.

`\D'E DX DY''
     Draw a solid elipse with the same parameters as an outlined elipse.

`\D'a DX1 DY1 DX2 DY2''
     Draw an arc clockwise from the current location through the two
     specified locations.

`\D'~ DX1 DY1 DX2 DY2 ...''
     Draw a spline from the current location to DX1, DY1 and then to
     DX2, DY2, and so on.

`\D'f N''
     Set the shade of gray to be used for filling solid objects to N; N
     must be an integer between 0 and 1000, where 0 corresponds solid
     white and 1000 to solid black, and values in between correspond to
     intermediate shades of gray.  This applies only to solid circles,
     solid ellipses and solid polygons.  By default, a level of 1000
     will be used.

`\D'p DX1 DY1 DX2 DY2 ...''
     Draw a polygon from the current location to DX1, DY1 and then to
     DX2, DY2 and so on.  When the specified data points are exhausted,
     a line is drawn back to the starting point.

`\D'P DX1 DY1 DX2 DY2 ...''
     Draw a solid polygon with the same parameters as an outlined
     polygon.

`\D't N''
     Set the current line thickness to N machine units.  A value of
     zero selects the smallest available line thickness.

   The `\b' escape will "pile" a sequence of characters vertically, and
center it vertically on the current line.  This can be used to build
large brackets and braces.

     \b'\(lt\(bv\(lk\(bv\(lb'


File: groff.info,  Node: Traps,  Next: Diversions,  Prev: Drawing Functions,  Up: Programming Tutorial

Traps
=====

   Traps are locations, which, when reached, will call a specified
macro.  These traps can occur at a given location on the page, at a
given location in the current diversion, after a certain number of input
lines or at the end of input.

   Any of these traps can be changed after they have been set with the
`ch' request.  The first argument is the name of the trap or macro, and
the second is the new value for that trap.  *Note Page Location Traps::.

* Menu:

* Page Location Traps::
* Diversion Traps::
* Input Line Traps::
* End-of-input Traps::


File: groff.info,  Node: Page Location Traps,  Next: Diversion Traps,  Prev: Traps,  Up: Traps

Page Location Traps
-------------------

   Page location traps are frequently used for page headers and
footers.  The following is a simple example of this.

     .de hd                          \" Page header
     'sp .5i
     .tl 'Title''date'
     'sp .3i
     ..
     .de fo                          \" Page footer
     'sp 1v
     .tl ''%''
     'bp
     ..
     .wh 0   hd                      \" top of the page
     .wh -1i fo                      \" one inch from bottom

   The number register `.t' is the distance to the next trap.

   The location of a trap can be changed later on with the `ch' request.
The first argument is the name of the macro to be invoked at the trap
and the second argument is the new location for the trap.  This is
useful when you are building up footnotes in a diversion, and you need
to allow more space at the bottom of the page for them.

   The `vpt' request will enable vertical position traps if the argment
is non-zero, disable them otherwise.  Vertical position traps are traps
set by the `wh' or `dt' requests.  Traps set by the `it' request are
not vertical position traps.  The parameter that controls whether
vertical position traps are enabled is global.  Initially vertical
position traps are enabled.  The current setting of this is available
in the number register `.vpt'.

   The number register `.trunc' contains the amount of vertical space
truncated by the most recently sprung vertical position trap, or, if
the trap was sprung by a `ne' request, minus the amount of vertical
motion produced by the `ne' request.  In other words, at the point a
trap is sprung, it represents the difference of what the vertical
position would have been but for the trap, and what the vertical
position actually is.

   The number register `.ne' contains the amount of space that was
needed in the last `ne' request that caused a trap to be sprung.
Useful in conjunction with the `.trunc' register.  *Note Page
Control::, for more information.


File: groff.info,  Node: Diversion Traps,  Next: Input Line Traps,  Prev: Page Location Traps,  Up: Traps

Diversion Traps
---------------

   Traps can also be set _within_ a diversion using the `dt' request.
Like `wh' the first argument is the location of the trap and the second
argument is the name of the macro to be invoked.  The number register
`.t' will still work within diversions.  *Note Diversions::, for more
information.


File: groff.info,  Node: Input Line Traps,  Next: End-of-input Traps,  Prev: Diversion Traps,  Up: Traps

Input Line Traps
----------------

   The `it' request will set an input line trap.  The format for
calling this is `.it N NAME', where N is the number of lines of input
which may be read before "springing" the trap, NAME is the macro to be
invoked.  Request lines are not counted as input lines.

   For example, one possible use is to have a macro which will print the
next N lines in a bold font.

     .de B
     .it B-end \\$1
     .ft B
     ..
     .de B-end
     .ft R
     ..


File: groff.info,  Node: End-of-input Traps,  Prev: Input Line Traps,  Up: Traps

End-of-input Traps
------------------

   The `em' request will set a trap at the end of input.  The macro
specified as an arguement will be executed after the last line of the
input file has been processed.

   For example, if your document had to have a section at the bottom of
the last page for someone to approve you document, you could set it up
with `em'.

     .de approval
     .ne 5v
     .sp |(\\n(.t-6v)
     .in +4i
     .lc _
     .br
     Approved:\t\a
     .sp
     Date:\t\t\a
     ..
     .em approval


File: groff.info,  Node: Diversions,  Next: Environments,  Prev: Traps,  Up: Programming Tutorial

Diversions
==========

   In Troff you can divert text into a named storage area, due to the
similarity to defining macros it is sometimes said to be stored in a
macro.  This is used for saving text for output at a later time, which
is useful for keeping blocks of text on the same page, footnotes,
tables of contents and indexes.

   Diversion is initiated by the `di' request, like the `de' request it
takes an argument of a macro name to divert subsequent text to into.
The `da' macro will append to an existing diversion.

   Diversions may be nested.  The number register `.z' contains the
name of the current diversion.  The number register `.d' contains the
current vertical place in the diversion.  If not in a diversion it is
the same as the register `nl'.  `.h'

   After completing a diversion, the builtin number registers `dn' and
`dl' contain the vertical and horizontal size of the diversion.

     .\" Center text both horizontally & vertically
     .de (c
     .br
     .nf
     .di @c
     ..
     .de )c
     .br
     .di
     .nr @s (((\\n(.tu-\\n(dnu)/2u)-1v)
     .sp \\n(@su
     .ce 1000
     .nf
     ..br
     .ce 0
     .sp \\n(@su
     .br
     .fi
     .rr @s
     ..

   Requests, macros and escapes are interpreted when read into a
diversion.  There are two ways to prevent this, either way will take
the given text and "transparently" embed it into the diversion.  The
first method is to prefix the line with `\!'.  This will cause the
entire line to be transparently inserted into the diversion.  This is
useful for macros you do not want invoked until the diverted text is
actually output.

   The other way is to surround the text by the `\?' escape, i.e.
`\?ANYTHING\?'.  ANYTHING may not  contain newlines; use `\!' if you
want to embed newlines in a diversion.  The escape sequence `\?' is
also recognised in copy mode and turned into a single internal code; it
is this code that terminates anything.  Thus the followin example will
print 4.

     .nr x 1
     .nf
     .di d
     \?\\?\\\\?\\\\\\\\nx\\\\?\\?\?
     .di
     .nr x 2
     .di e
     .d
     .di
     .nr x 3
     .di f
     .e
     .di
     .nr x 4
     .f

   `rn'

   `rm'

   `als'

   `chop'

   The `asciify' request only exists in order to make it possible to
make certain gross hacks work with GNU `troff'.  It "unformats" the
diversion specified as an argument in such a way that ASCII characters
that were formatted and diverted will be treated like ordinary input
characters when the diversion is reread.  For example, the following
will set register `n' to 1.

     .tr  @.
     .di  x
     @nr\  n\  1
     .br
     .di
     .tr  @@
     .asciify  x
     .x

   *Note Copy-in Mode::.


File: groff.info,  Node: Environments,  Next: I/O,  Prev: Diversions,  Up: Programming Tutorial

Environments
============

   Often you will need to print some text in a certain format regardless
of what may be in effect at the time, for example, in a trap invoked
macro to print headers and footers.  To solve this, `groff' has
"environments" in which text is processed.  An environment contains
most of the parameters that control text processing.  You can switch
amongst these environments; by default, `groff' processes text in
environment 0.  The following is the information kept in an environment.

   * type size

   * font (family and style)

   * page parameters

   * fill/adjust mode

   * tab stops

   * partially collected lines

   These environments may be given arbitrary names (see *Note
Identifiers::, for more info).  Old versions of `troff' only had
environments named 0, 1 and 2.

   The `ev' request will switch among these environments.  The single
argument is the name of the environment to switch to, with no argument
groff will switch back to the previous enviroment.  There is no limit
on the number of named environments; they will be created the first
time that they are referenced.  The `.ev' number register contains the
name or number of the current environment.  This is a string-valued
register.

     ... page break macro, revised ...

     .ev footnote-env
     .fam N
     .ps 6
     .vs 8
     .ll -.5i
     .ev
     ...
     .ev footnote-env
     \(dg Note the large, friendly letters.
     .ev


File: groff.info,  Node: I/O,  Next: Postprocessor Access,  Prev: Environments,  Up: Programming Tutorial

I/O
===

   The `so' request will read in the file given as an argument and
include it in place of the `so' request.  This is quite useful for
large documents, i.e. keeping each chapter in a separate file.

   The `mso' request is the same as the `so' request except that file
is searched for in the same way that `tmac.NAME' is searched for when
the `-mNAME' option is specified.

   The `cf' and `trf' requests are to include a file.  It will
transparently output the contents of file filename.  Each line is output
as it would be were it preceded by `\!'; however, the lines are not
subject to copy-mode interpretation.  If the file does not end with a
newline, then a newline will be added.  For example, you can define a
macro `x' containing the contents of file `f', using

     .di x
     .trf f
     .di

   The request `.cf FILENAME', when  used  in  a  diversion, will embed
in the diversion an object which, when reread, will cause the contents
of FILENAME to be transparently copied through to the output.  In UNIX
`troff', the contents of FILENAME is immediately copied through to the
output regardless of whether there is a current diversion; this
behaviour is so anomalous that it must be considered a bug.

   With `trf', unlike `cf', the file cannot contain characters such as
NUL that are not valid `troff' input characters.

   The `nx' request will force `groff' to continue processing of the
file specified as an argument.

   The `rd' request will read from standard input, and include what is
read as though it were part of the input file.  Text is read until a
blank line is encountered.

   Using these two requests you can set up form letters.  The form
letter template is constructed like this:

     .ce
     \*(td
     .sp 2
     .nf
     .rd
     .sp
     .rd
     .fi
     Body of letter.
     .bp
     .nx repeat.let

   When this is run, the following file should be redirected in.  Note
that requests included in this file are executed as though they were
part of the form letter.  The last block of input is the `ex' requests
which tells groff to stop processing.  If this was not there, groff
would not know when to stop.

     Trent A. Fisher
     708 NW 19th Av., #202
     Portland, OR  97209
     
     Dear Trent,
     
     Len Adollar
     4315 Sierra Vista
     San Diego, CA  92103
     
     Dear Mr. Adollar,
     
     .ex

   `pi'

   The `sy' request will allow arbitrary system commands to be executed
from within a groff document.  The output is not saved anyplace, so it
is up to you to do so.

   For example, the following example will introduce the current time
into your document:

     .sy perl -e 'printf ".nr H %d\\n.nr M %d\\n.nr S %d\\n",\
     	     (localtime(time))[2,1,0]' > /tmp/x\n[$$]
     .so /tmp/x\n[$$]
     .sy rm /tmp/x\n[$$]
     \nH:\nM:\nS

   Note that this works by having the perl script (run by `sy') print
out the `nr' requests which will set the number registers `H', `M' and
`S', and then reads those commands in with the `so' request.

   The `systat' number register contains The return value of the
`system()' function executed by the last `sy' request.

   The `open' request will open a file (specified as the second
argument) for writing and associate the stream (specified as the first
argument) with it.

   The `opena' is like open, but if filename exists, append to it
instead of truncating it.

   The `write' request will write to the file associated with the
stream specified by the first argument.  The stream must previously
have been the subject of an open request.  The remainder of the line in
interpreted as the `ds' request reads its second argument: a leading
`"' will be stripped, and it will be read in copy-in mode.

   The `close' request will close the stream specified by the first
argument; stream will no longer be an acceptable argument to the
`write' request.

   The `\V' escape will interpolate the contents of the specified
environment variable, as returned by `getenv(3)'.  The argument to `\V'
is specified as an identifier, i.e.  `\VX', `\V(XX' or `\V[XXX]'.  `\V'
is interpreted in copy-in mode.


File: groff.info,  Node: Postprocessor Access,  Next: Miscellany,  Prev: I/O,  Up: Programming Tutorial

Postprocessor Access
====================

   There are two escapes which will allow you to give information
directly to the postprocessor.  This is particularly useful for
embedding PostScript into your final document.

   The `\X' escape will embed its argument into the gtroff output
preceded with `x X'.

   The `\Y' escape is called with an identifier (i.e.  `\YX', `\Y(XX' or
`\Y[XXX]').  This is approximately equivalent to `\X'\*[XXX]''.
However the contents of the string or macro XXX are not interpreted;
also it is permitted for XXX to have been defined as a macro and thus
contain newlines (it is not permitted for the argument to `\X' to
contain newlines).  The inclusion of newlines requires an extetension
to the UNIX `troff' output format, and will confuse drivers that do not
know about this extension.


File: groff.info,  Node: Miscellany,  Next: Debugging,  Prev: Postprocessor Access,  Up: Programming Tutorial

Miscellany
==========

   This section contains parts of `troff' which cannot (yet) be
categorized elsewhere in this manual.

   Line numbers can be printed in the left margin using the `nm'
request.  The first argument is the line number of the _next_ output
line, this defaults to 1.  The second argument indicates on which lines
numbers will be printed, i.e. 5 means put line numbers on every 5
lines, this defaults to 1.  The third argument is the space to be left
between the number and your text, this defaults to 1.  The fourth
argument is the indentation of the line numbers.  Without arguments,
line numbers are turned off.

   The `nn' request will temporarily turn off line numbering.  The
first argument is the number of lines not to be numbered, this defaults
to 1. (does this disable incrementing or display?)

   margin characters can be automatically printed to the right of your
text with the `mc' request.  The first argument is the character to be
printed and the second argument is the distance away from your text.
With no arguments the margin characters are turned off.  If this occurs
before a break, no margin character will be printed.

   This is quite useful for indicating text that has changed, and, in
fact, there are programs available for doing this (they are called
`nrchbar' and `changebar' and can be found in any `comp.sources.unix'
archive.

   The `lf' primary reason for existence is to make debugging documents
which are split into many files, which are then put together with
`soelim' and other preprocessors.  The first argument is the name of
the file and the second argument is the input line number in that file.
This way `troff' can produce error messages which are intelligible to
the user.


File: groff.info,  Node: Debugging,  Next: Implementation Differences,  Prev: Miscellany,  Up: Programming Tutorial

Debugging
=========

   Troff is not easy to debug, but there are some useful features and
strategies for debugging.

   * The `tm' request will send output to the standard error stream,
     this is very useful for printing debugging output.

   * When doing something involved it is useful to leave the debugging
     statements in the code and have them turned on by a command line
     flag.

          .if \n(DB .tm debugging output

     Then you can activate these statements with:

          groff -rDB=1 file

   * The `ab' request is similar to the `tm' request, except that it
     will cause groff to stop processing.  With no argument it will
     print `User Abort'.

   * The `ex' request will also cause `groff' to stop processing.

   * If you know you are going to get many errors and no useful output,
     you can tell `groff' to suppress formatted output with the `-z'
     flag.

   * The `pm' request will dump out the entire symbol table.

   * The `pnr' request will print the names and contents of all
     currently defined number registers on stderr.

   * The `ptr' request will print the names and positions of all traps
     (not including input line traps and diversion traps) on stderr.
     Empty slots in the page trap list are printed as well, because
     they can affect the priority of subsequently planted traps.

   * The `fl' request instructs `groff' to flush its output immediately.
     The intention is that this be used when using `troff'
     interactively.  There is little other use for it.

   * The `backtrace' request will print a backtrace of the input stack
     on `stderr'.

   * Groff has command line options for printing out more warnings
     (`-w') and for printing backtraces (`-b') when a warning or an
     error occurs.  The most verbose level of warnings is `-ww'.

   * The `warn' request controls the level of warnings checked for.
     The one argument is the sum of the numbers associated with each
     warning that is to be enabled; all other warnings will be disabled.
     The number associated with each warning is listed below.  For
     example, `.warn 0' will disable all warnings, and `.warn 1' will
     disable all warnings except that about missing characters.  If an
     argument is not given, all warnings will be enabled.  The number
     register `.warn' contains the current warning level.

Warnings
--------

   The warnings that can be given by `troff' are divided into the
following categories.  The name associated with each warning is used by
the `-w' and `-W' options; the number is used by the `warn' request,
and by the `.warn' register.

`char'
`1'
     Non-existent characters.  This is enabled by default.

`number'
`2'
     Invalid numeric expressions.  This is enabled by default.

`break'
`4'
     In fill mode, lines which could not be broken so that their length
     was less than the line length.  This is enabled by default.

`delim'
`8'
     Missing or mismatched closing delimiters.

`el'
`16'
     Use of the `el' request with no matching `ie' request.  *Note
     if-else::, for more information.

`scale'
`32'
     Meaningless scaling indicators.

`range'
`64'
     Out of range arguments.

`syntax'
`128'
     Dubious syntax in numeric expressions.

`di'
`256'
     Use of `di' or `da' without an argument when there is no current
     diversion.

`mac'
`512'
     Use of undefined strings, macros and diversions.  When an
     undefined string, macro or diversion is used, that string is
     automatically defined as empty.  So, in most cases, at most one
     warning will be given for each name.

`reg'
`1024'
     Use of undefined number registers.  When an undefined number
     register is used, that register is automatically defined to have a
     value of 0.  a definition is automatically made with a value of 0.
     So, in most cases, at most one warning will be given for use of a
     particular name.

`tab'
`2048'
     Use of a tab character where a number was expected.

`right-brace'
`4096'
     Use of `\}' where a number was expected.

`missing'
`8192'
     Requests that are missing non-optional arguments.

`input'
`16384'
     Illegal input characters.

`escape'
`32768'
     Unrecognized escape sequences.  When an unrecognized escape
     sequence is encountered, the escape character is ignored.

`space'
`65536'
     Missing space between a request or macro and its argument.  This
     warning will be given when  an undefined name longer than two
     characters is encountered, and the first two characters of the name
     make a defined name.  The request or macro will not be invoked.
     When this warning is given, no macro is automatically defined.
     This is enabled by default.  This warning will never occur in
     compatibility mode.

`font'
`131072'
     Non-existent fonts. This is enabled by default.

`all'
     All warnings except `di', `mac' and `reg'. It is intended that
     this covers all warnings that are useful with traditional macro
     packages.

`w'
     All warnings.


File: groff.info,  Node: Implementation Differences,  Next: Summary,  Prev: Debugging,  Up: Programming Tutorial

Implementation Differences
==========================

   GNU `troff' has a number of features which cause incompatibilites
with documents written with old versions of `troff'.

   Long names cause some incompatibilities.  UNIX `troff' will interpret

     .dsabcd

as defining a string `ab' with contents `cd'.  Normally, GNU `troff'
will interpret this as a call of a macro named `dsabcd'.  Also UNIX
`troff' will interpret `\*[' or `\n[' as references to a string or
number register called `['.  In GNU `troff', however, this will
normally be interpreted as the start of a long name.  In compatibility
mode GNU `troff' will interpret these things in the traditional way.
In compatibility mode, however, long names are not recognised.
Compatibility mode can be turned on with the `-C' command line option,
and turned on or off with the `cp' request.  The number register `.C'
is 1 if compatibility mode is on, 0 otherwise.

   GNU `troff' does not allow the use of the escape sequences `\| \^ \&
\} \{ \<SP> \' \` \- \_ \! \% \c' in names of strings, macros,
diversions, number registers, fonts or environments; UNIX `troff' does.
The `\A' escape sequence may be helpful in avoiding use of these escape
sequences in names.

   Fractional pointsizes cause one noteworthy incompatibility.  In UNIX
`troff' the `ps' request ignores scale indicators and so

     .ps 10u

   will set the pointsize to 10 points, whereas in GNU `troff' it will
set the pointsize to 10 scaled points.  *Note Fractional Type Sizes::,
for more information.

   In GNU `troff' there is a fundamental difference between unformatted
input characters, and formatted output characters.  Everything that
affects how an output character will be output is stored with the
character; once an output character has been constructed it  is
unaffected by any subsequent requests that are executed, including
`bd', `cs', `tkf', `tr', or `fp' requests.  Normally output characters
are constructed from input characters at the moment immediately before
the character is added to the current output line.  Macros, diversions
and strings are all, in fact, the same type of object; they contain
lists of input characters and output characters in any combination.  An
output character does not behave like an input character for the
purposes of macro processing; it does not inherit any of the special
properties that the input character from which it was constructed might
have had. For example,

     .di x
     \\\\
     .br
     .di
     .x

   will print `\\' in GNU `troff'; each pair of input backslashes is
turned into one output backslash and the resulting output backslashes
are not interpreted as escape characters when they are reread. UNIX
`troff' would interpret them as escape characters when they were reread
and would end up printing one `\'.  The correct way to obtain a
printable backslash is to use the `\e' escape sequence: this will
always print a single instance of the current escape character,
regardless of whether or not it is used in a diversion; it will also
work in both GNU `troff' and UNIX `troff'.  If you wish for some reason
to store in a diversion an escape sequence that will be interpreted
when the diversion is reread, you can either use the traditional `\!'
transparent output facility, or, if this is unsuitable, the new `\?'
escape sequence.  *Note Diversions::, for more information.


File: groff.info,  Node: Summary,  Prev: Implementation Differences,  Up: Programming Tutorial

Summary
=======


File: groff.info,  Node: File formats,  Next: Request Index,  Prev: Programming Tutorial,  Up: Top

File formats
************

* Menu:

* gtroff Output::
* Font Files::


File: groff.info,  Node: gtroff Output,  Next: Font Files,  Prev: File formats,  Up: File formats

`gtroff' Output
===============

   This section describes the format output by GNU `troff'.  The output
format used by GNU `troff' is very similar to that used by UNIX
device-independent `troff'.

   The output format is ASCII based, as opposed to a binary format (like
TeX dvi).  The output format is 8 bit clean, thus single characters can
have the eighth bit set, as can the names of fonts and special
characters.

   The output format consists of single command characters with attached
parameters which are separated from subsequent text by whitespace or a
newline.

   The names of characters and fonts can be of arbitrary length; drivers
should not assume that they will be only two characters long (as
device-independent `troff' did).

   When a character is to be printed, that character will always be in
the current font.  Unlike device-independent `troff', it is not
necessary for drivers to search special fonts to find a character.

`HN'

`VN'

`hN'

`vN'

`cN'

`CN'

`NNC'

`tXXX'
     XXX is any sequence of characters terminated by a space or a
     newline; the first character should be printed at the current
     position, the the current horizontal position should be increased
     by the width of the first character, and so on for each character.
     The width of the character is that given in the font file,
     appropriately scaled for the current point size, and rounded so
     that it is a multiple of the horizontal resolution.  Special
     characters cannot be printed using this command.

     This command is only allowed if the `tcommand' line is present in
     the `DESC' file.

`uN XXX'
     This is same as the `t' command except that after printing each
     character, the current horizontal position is increased by the sum
     of the width of that character and `n'.

     This command is only allowed if the `tcommand' line is present in
     the `DESC' file.

`nAB'

`pN'

`sN'
     The argument to the s command is in scaled points (units of
     points/n, where n is the argument to the sizescale command  in the
     `DESC' file.)

`fN'

`x ... \n'
     Device control.

`DC X...\n'
Device Control
--------------

   The `x' command is normally followed by a letter or word indicating
the function to perform, followed by white space separated arguments.

   The first argument can be abreviated to the first letter.

`x init'

`x T'

`x res N H V'

`x H'
     The argument to the x Height command is also in scaled points.

   The first three output commands are guaranteed to be:

     x T device
     x res n h v
     x init

Drawing Functions
-----------------

   The D drawing command has been extended.  These extensions will only
be used by GNU `pic' if the `-x' option is given.

     ...

`Df n\n'
     Set the shade of gray to be used for filling solid objects to n; n
     must be an integer between 0 and 1000, where 0 corresponds solid
     white and 1000 to solid black, and values in between correspond to
     intermediate shades of gray.  This applies only to solid circles,
     solid ellipses and solid polygons.  By default, a level of 1000
     will be used.  Whatever color a solid object has, it should
     completely obscure everything beneath it. A value greater than
     1000 or less than 0 can also be used: this means fill with the
     shade of gray that is currently being used for lines and text.
     Normally this will be black, but some drivers may provide a way of
     changing this.

`DC d\n'
     Draw a solid circle with a diameter of d with the leftmost point
     at the current position.

`DE dx dy\n'
     Draw a solid ellipse with a horizontal diameter of dx and a
     vertical diameter of dy with the leftmost point at the current
     position.

`Dp $dx sub 1$ $dy sub 1$ $dx sub 2$ $dy sub 2$ $...$ $dx sub n$ $dy sub'
     n$\n Draw a polygon with, for $i = 1 ,..., n+1$, the i-th vertex
     at the current position $+ sum from j=1 to i-1 ( dx sub j , dy sub
     j )$. At the moment, GNU pic only uses this command to generate
     triangles and rectangles.

`DP $dx sub 1$ $dy sub 1$ $dx sub 2$ $dy sub 2$ $...$ $dx sub n$ $dy sub'
     n$\n Like Dp but draw a solid rather than outlined polygon.

`Dt n\n'
     Set the current line thickness to n machine units.  Traditionally
     UNIX `troff' drivers use a line thickness proportional to the
     current point size; drivers should continue to do this if no Dt
     command has been given, or if a Dt command has been given with a
     negative value of n.  A zero value of n selects the smallest
     available line thickness.

   A difficulty arises in how the current position should be changed
after the execution of these commands. This is not of great importance
since the code generated by GNU pic does not depend on this. Given a
drawing command of the form `\D'c $x sub 1$ $y sub 1$ $x sub 2$ $y sub
2$ $...$ $x sub n$ $y sub n$'' where c is not one of c, e, l, a or ~,
UNIX `troff' will treat each of the $x sub i$ as a horizontal quantity,
and each of the $y sub i$ as a vertical quantity and will assume that
the width of the drawn object is $sum from i=1 to n x sub i$, and that
the height is $sum from i=1 to n y sub i$.  (The assumption about the
height can be seen by examining the st and sb registers after using
such a D command in a \w escape sequence.)  This rule also holds for
all the original drawing commands with the exception of De.  For the
sake of compatibility GNU `troff' also follows this rule, even though
it produces an ugly result in the case of the Df, Dt, and, to a lesser
extent, DE commands.  Thus after executing a D command of the form `Dc
$x sub 1$ $y sub 1$ $x sub 2$ $y sub 2$ $...$ $x sub n$ $y sub n$\n'
the current position should be increased by $( sum from i=1 to n x sub i
, sum from i=1 to n y sub i )$.

Line Continuation
-----------------

   There is a continuation convention which permits the argument to the
x X command to contain newlines: when outputting the argument to the x X
command,  GNU `troff' will follow each newline in the argument with a +
character (as usual, it will terminate the entire argument with a
newline); thus if the line after the line containing the x X command
starts with +, then the newline ending the line containing the x X
command should be treated as part of the argument to the x X command,
the + should be ignored, and the part of the line following the + should
be treated like the part of the line following the x X command.


File: groff.info,  Node: Font Files,  Prev: gtroff Output,  Up: File formats

Font Files
==========

   The groff font format is roughly a superset of the `ditroff' font
format.  Unlike the `ditroff' font format, there is no associated binary
format.  The font files for device NAME are stored in a directory
`devNAME'.  There are two types of files: a device description file
called `DESC', and for each font F a font file called `F'.  These are
text files; there is no associated binary format.

`DESC' file format
------------------

   The `DESC' file can contain the following types of line:

`res N'
     There are N machine units per inch.

`hor N'
     The horizontal resolution is N machine units.

`vert N'
     The vertical resolution is N machine units.

`sizescale N'
     The scale factor for pointsizes.  By default this has a value of
     1.  One scaled point is equal to one point/N.  The arguments to the
     `unitwidth' and `sizes' commands are given in scaled points.
     *Note Fractional Type Sizes::, for more information.

`unitwidth N'
     Quantities in the font files are given in machine units for fonts
     whose point size is N scaled points.

`tcommand'
     This means that the postprocessor can handle the `t' and `u'
     output commands.

`sizes S1 S2...SN 0'
     This means that the device has fonts at S1, S2, ...SN scaled
     points.  The list of sizes must be terminated by a 0.  Each SI can
     also be a range of sizes M-N.  The list can extend over more than
     one line.

`styles S1 S2...SM'
     The first M font positions will be associated with styles S1...SM.

`fonts N F1 F2 F3...FN'
     Fonts F1...FN will be mounted in the font positions M+1, ..., M+N
     where M is the number of styles.  This command may extend over
     more than one line. A font name of 0 will cause no font to be
     mounted on the corresponding font position.

`family FAM'
     The default font family is FAM.

`charset'
     This line and everything following in the file are ignored.  It is
     allowed for the sake of backwards compatibility.

   The `res', `unitwidth', `fonts' and `sizes' lines are mandatory.
Other commands are ignored by `troff' but may be used by postprocessors
to store arbitrary information about the device in the `DESC' file.

Font file format
----------------

   A font file has two sections.  The first section is a sequence of
lines each containing a sequence of blank delimited words; the first
word in the line is a key, and subsequent words give a value for that
key.

`name F'
     The name of the font is F.

`spacewidth N'
     The normal width of a space is N.

`slant N'
     The characters of the font have a slant of N degrees.  (Positive
     means forward.)

`ligatures LIG1 LIG2...LIGN [0]'
     Characters LIG1, LIG2, ..., LIGN are ligatures; possible ligatures
     are ff, fi, fl and ffl.  For backwards compatibiliy, the list of
     ligatures may be terminated with a 0.  The list of ligatures may
     not extend over more than one line.

`special'
     The font is special; this means that when a character is requested
     that is not present in the current font, it will be searched for
     in any special fonts that are mounted.

   Other commands are ignored by `troff' but may be used by
postprocessors to store arbitrary information about the font in the
font file.

   The first section can contain comments which start with the `#'
character and extend to the end of a line.

   The second section contains one or two subsections.  It must contain
a `charset' subsection and it may also contain a `kernpairs'
subsection.  These subsections can appear in any order.  Each
subsection starts with a word on a line by itself.

   The word `charset' starts the `charset' subsection. The `charset'
line is followed by a sequence of lines. Each line gives information
for one character.  A line comprises a number of fields separated by
blanks or tabs. The format is

     NAME METRICS TYPE CODE COMMENT

   NAME identifies the character: if NAME is a single character C then
it corresponds to the `groff' input character C; if it is of the form
`\C' where C is a single character, then it corresponds to the `groff'
input character `\C'; otherwise it corresponds to the `groff' input
character `\[NAME]' (if it is exactly two characters XX it can be
entered as `\(XX'.) Groff supports eight bit characters; however some
utilities has difficulties with eight bit characters.  For this reason,
there is a convention that the NAME `charN' is equivalent to the single
character whose code is N. For example, `char163' would be equivalent
to the character with CODE 163 which is the pounds sterling sign in ISO
Latin-1 character set.  The name `---' is special and indicates that
the character is unnamed; such characters can only be used by means of
the `\N' escape sequence in `troff'.

   The TYPE field gives the character type:

`1'
     means the character has an descender, for example, p;

`2'
     means the character has an ascender, for example, b;

`3'
     means the character has both an ascender and a descender, for
     example, `('.

   The CODE field gives the code which the postprocessor uses to print
the character.  The character can also be input to groff using this
code by means of the `\N' escape sequence. The code can be any integer.
If it starts with a 0 it will be interpreted as octal; if it starts
with `0x' or `0X' it will be intepreted as hexdecimal.

   Anything on the line after the CODE field will be ignored.

   The METRICS field has the form (as a single long line):

     WIDTH[,HEIGHT[,DEPTH
       [,ITALIC_CORRECTION[,LEFT_ITALIC_CORRECTION
       [,SUBSCRIPT_CORRECTION]]]]]

   There must not be any spaces between these subfields.  Missing
subfields are assumed to be 0.  The subfields are all decimal integers.
Since there is no associated binary format, these values are not
required to fit into a variable of type `char' as they are in ditroff.
The WIDTH subfields gives the width of the character.  The HEIGHT
subfield gives the height of the character (upwards is positive); if a
character does not extend above the baseline, it should be given a zero
height, rather than a negative height.  The DEPTH subfield gives the
depth of the character, that is, the distance below the lowest point
below the baseline to which the character extends (downwards is
positive); if a character does not extend below above the baseline, it
should be given a zero depth, rather than a negative depth.  The
ITALIC_CORRECTION subfield gives the amount of space that should be
added after the character when it is immediately to be followed by a
character from a roman font.  The LEFT_ITALIC_CORRECTION subfield gives
the amount of space that should be added before the character when it is
immediately to be preceded by a character from a roman font.  The
SUBSCRIPT_CORRECTION gives the amount of space that should be added
after a character before adding a subscript. This should be less than
the italic correction.

   A line in the `charset' section can also have the format

     NAME "

   This indicates that NAME is just another name for the character
mentioned in the preceding line.

   The word `kernpairs' starts the kernpairs section.  This contains a
sequence of lines of the form:

     C1 C2 N

   This means that when character C1 appears next to character C2 the
space between them should be increased by N.  Most entries in kernpairs
section will have a negative value for N.


File: groff.info,  Node: Request Index,  Next: Register Index,  Prev: File formats,  Up: Top

Request Index
*************

* Menu:

* \!:                                    Diversions.
* \!, and trnt:                          Character Translations.
* \!, incompatibilities with Unix troff: Implementation Differences.
* \":                                    Comments.
* \#:                                    Comments.
* \$:                                    Parameters.
* \$*:                                   Parameters.
* \$, when reading test for a macro:     Copy-in Mode.
* \$0:                                   Parameters.
* \$@:                                   Parameters.
* \%:                                    Manipulating Hyphenation.
* \&:                                    Page Motions.
* \&, escaping control characters:       Requests.
* \(:                                    Using Symbols.
* \):                                    Page Motions.
* \*:                                    Strings.
* \*, incompatibilities with Unix troff: Implementation Differences.
* \*, when reading test for a macro:     Copy-in Mode.
* \,:                                    Changing Fonts.
* \/:                                    Changing Fonts.
* \0:                                    Page Motions.
* \<RET>:                                Strings.
* \<RET>, when reading test for a macro: Copy-in Mode.
* \<SP>:                                 Page Motions.
* \?:                                    Diversions.
* \?, incompatibilities with Unix troff: Implementation Differences.
* \[:                                    Using Symbols.
* \\:                                    Escapes.
* \\, when reading test for a macro:     Copy-in Mode.
* \^:                                    Page Motions.
* \a:                                    Tabs and Fields.
* \A:                                    Implementation Differences.
* \b:                                    Drawing Functions.
* \C:                                    Using Symbols.
* \d:                                    Page Motions.
* \D:                                    Drawing Functions.
* \e:                                    Escapes.
* \E:                                    Escapes.
* \e, incompatibilities with Unix troff: Implementation Differences.
* \f:                                    Changing Fonts.
* \g:                                    Assigning Formats.
* \h:                                    Page Motions.
* \k:                                    Page Motions.
* \L:                                    Drawing Functions.
* \l:                                    Drawing Functions.
* \n:                                    Interpolating Registers.
* \N:                                    Using Symbols.
* \n, incompatibilities with Unix troff: Implementation Differences.
* \n, when reading test for a macro:     Copy-in Mode.
* \p:                                    Manipulating Filling and Adjusting.
* \r:                                    Page Motions.
* \R:                                    Setting Registers.
* \s:                                    Changing Type Sizes.
* \t:                                    Tabs and Fields.
* \u:                                    Page Motions.
* \V:                                    I/O.
* \v:                                    Page Motions.
* \w:                                    Page Motions.
* \X:                                    Postprocessor Access.
* \x:                                    Manipulating Spacing.
* \Y:                                    Postprocessor Access.
* \{:                                    if-else.
* \|:                                    Page Motions.
* \}:                                    if-else.
* \}, debugging:                         Debugging.
* \~:                                    Page Motions.
* ab:                                    Debugging.
* ad:                                    Manipulating Filling and Adjusting.
* af:                                    Assigning Formats.
* aln:                                   Setting Registers.
* als:                                   Writing Macros.
* als, and diversions:                   Diversions.
* als, use with \$0:                     Parameters.
* am:                                    Writing Macros.
* as:                                    Strings.
* asciify:                               Diversions.
* backtrace:                             Debugging.
* bd:                                    Artificial Fonts.
* bd, incompatibilities with Unix troff: Implementation Differences.
* bp:                                    Page Control.
* br:                                    Basics.
* break, in a while loop:                while.
* c2:                                    Character Translations.
* cc:                                    Character Translations.
* ce:                                    Basics.
* cf:                                    I/O.
* cflags:                                Using Symbols.
* ch:                                    Page Location Traps.
* char:                                  Using Symbols.
* chop:                                  Strings.
* chop, and diversions:                  Diversions.
* close:                                 I/O.
* continue, in a while loop:             while.
* cp:                                    Implementation Differences.
* cs, incompatibilities with Unix troff: Implementation Differences.
* cu:                                    Artificial Fonts.
* da:                                    Diversions.
* da, debugging:                         Debugging.
* de:                                    Writing Macros.
* di:                                    Diversions.
* di, debugging:                         Debugging.
* ds:                                    Strings.
* dt:                                    Diversion Traps.
* ec:                                    Character Translations.
* el:                                    if-else.
* em:                                    End-of-input Traps.
* eo:                                    Character Translations.
* ev:                                    Environments.
* ex:                                    I/O.
* ex, use in debugging:                  Debugging.
* fam:                                   Font Families.
* fc:                                    Tabs and Fields.
* fi:                                    Manipulating Filling and Adjusting.
* fl:                                    Debugging.
* fp:                                    Font Positions.
* fp, incompatibilities with Unix troff: Implementation Differences.
* ft:                                    Changing Fonts.
* ftr:                                   Changing Fonts.
* hc:                                    Manipulating Hyphenation.
* hcode:                                 Manipulating Hyphenation.
* hla:                                   Manipulating Hyphenation.
* hlm:                                   Manipulating Hyphenation.
* hpf:                                   Manipulating Hyphenation.
* hw:                                    Manipulating Hyphenation.
* hy:                                    Manipulating Hyphenation.
* hym:                                   Manipulating Hyphenation.
* hys:                                   Manipulating Hyphenation.
* ie:                                    if-else.
* if:                                    if-else.
* if, operators to use with it:          Conditionals and Loops.
* ig:                                    Comments.
* in:                                    Line Layout.
* it:                                    Input Line Traps.
* kern:                                  Ligatures and Kerning.
* lc:                                    Tabs and Fields.
* lf:                                    Miscellany.
* lg:                                    Ligatures and Kerning.
* ll:                                    Line Layout.
* ls:                                    Manipulating Spacing.
* lt:                                    Page Layout.
* mc:                                    Miscellany.
* mk:                                    Page Motions.
* mso:                                   I/O.
* na:                                    Manipulating Filling and Adjusting.
* ne:                                    Page Control.
* ne, and the .trunc register:           Page Location Traps.
* nf:                                    Manipulating Filling and Adjusting.
* nh:                                    Manipulating Hyphenation.
* nm:                                    Miscellany.
* nn:                                    Miscellany.
* nr:                                    Setting Registers.
* ns:                                    Manipulating Spacing.
* nx:                                    I/O.
* open:                                  I/O.
* opena:                                 I/O.
* os:                                    Page Control.
* pc:                                    Page Layout.
* pi:                                    I/O.
* pl:                                    Page Layout.
* pm:                                    Debugging.
* pn:                                    Page Layout.
* pnr:                                   Debugging.
* po:                                    Line Layout.
* ps:                                    Changing Type Sizes.
* ps, incompatibilities with Unix troff: Implementation Differences.
* ptr:                                   Debugging.
* rchar:                                 Using Symbols.
* rd:                                    I/O.
* rj:                                    Manipulating Filling and Adjusting.
* rm:                                    Strings.
* rm, and diversions:                    Diversions.
* rn:                                    Strings.
* rn, and diversions:                    Diversions.
* rnn:                                   Setting Registers.
* rr:                                    Setting Registers.
* rs:                                    Manipulating Spacing.
* rt:                                    Page Motions.
* shc:                                   Manipulating Hyphenation.
* shift:                                 Parameters.
* so:                                    I/O.
* sp:                                    Manipulating Spacing.
* sp, as vertical page motion:           Page Motions.
* ss:                                    Manipulating Filling and Adjusting.
* sv:                                    Page Control.
* sy:                                    I/O.
* ta:                                    Tabs and Fields.
* tc:                                    Tabs and Fields.
* ti:                                    Line Layout.
* tkf:                                   Ligatures and Kerning.
* tkf, incompatibilities with Unix troff: Implementation Differences.
* tl:                                    Page Layout.
* tm:                                    Debugging.
* tr:                                    Character Translations.
* tr, incompatibilities with Unix troff: Implementation Differences.
* trf:                                   I/O.
* trnt:                                  Character Translations.
* uf:                                    Artificial Fonts.
* ul:                                    Artificial Fonts.
* vpt:                                   Page Location Traps.
* vs:                                    Changing Type Sizes.
* warn:                                  Debugging.
* wh:                                    Page Location Traps.
* while:                                 while.
* while, operators to use with it:       Conditionals and Loops.
* write:                                 I/O.


File: groff.info,  Node: Register Index,  Next: Program Index,  Prev: Request Index,  Up: Top

Register Index
**************

* Menu:

* %:                                     Page Layout.
* .$:                                    Parameters.
* .A:                                    Builtin Registers.
* .a:                                    Manipulating Spacing.
* .c:                                    Builtin Registers.
* .C:                                    Implementation Differences.
* .ce:                                   Manipulating Filling and Adjusting.
* .d:                                    Diversions.
* .ev:                                   Environments.
* .f:                                    Font Positions.
* .fam:                                  Font Families.
* .fp:                                   Font Positions.
* .g:                                    Builtin Registers.
* .h:                                    Diversions.
* .H:                                    Builtin Registers.
* .hla:                                  Manipulating Hyphenation.
* .hlc:                                  Manipulating Hyphenation.
* .hlm:                                  Manipulating Hyphenation.
* .hy:                                   Manipulating Hyphenation.
* .hym:                                  Manipulating Hyphenation.
* .hys:                                  Manipulating Hyphenation.
* .i:                                    Line Layout.
* .in:                                   Line Layout.
* .j:                                    Manipulating Filling and Adjusting.
* .k:                                    Page Motions.
* .kern:                                 Ligatures and Kerning.
* .L:                                    Manipulating Spacing.
* .l:                                    Line Layout.
* .lg:                                   Ligatures and Kerning.
* .ll:                                   Line Layout.
* .lt:                                   Page Layout.
* .ne:                                   Page Location Traps.
* .o:                                    Line Layout.
* .P:                                    Builtin Registers.
* .p:                                    Page Layout.
* .pn:                                   Page Layout.
* .rj:                                   Manipulating Filling and Adjusting.
* .s:                                    Changing Type Sizes.
* .ss:                                   Manipulating Filling and Adjusting.
* .sss:                                  Manipulating Filling and Adjusting.
* .t:                                    Page Location Traps.
* .t, and diversions:                    Diversion Traps.
* .tabs:                                 Tabs and Fields.
* .trunc:                                Page Location Traps.
* .u:                                    Manipulating Filling and Adjusting.
* .v:                                    Changing Type Sizes.
* .V:                                    Builtin Registers.
* .vpt:                                  Page Location Traps.
* .warn:                                 Debugging.
* .x:                                    Builtin Registers.
* .y:                                    Builtin Registers.
* .z:                                    Diversions.
* c.:                                    Builtin Registers.
* ct:                                    Page Motions.
* dl:                                    Diversions.
* dn:                                    Diversions.
* dw:                                    Builtin Registers.
* dy:                                    Builtin Registers.
* ln:                                    Builtin Registers.
* mo:                                    Builtin Registers.
* nl:                                    Diversions.
* rsb:                                   Page Motions.
* rst:                                   Page Motions.
* sb:                                    Page Motions.
* skw:                                   Page Motions.
* ssc:                                   Page Motions.
* st:                                    Page Motions.
* systat:                                I/O.
* yr:                                    Builtin Registers.


File: groff.info,  Node: Program Index,  Next: Concept Index,  Prev: Register Index,  Up: Top

Program Index
*************

* Menu:

* DESC file format:                      Font Files.
* DESC, and font mounting:               Font Positions.
* DESC, and tcommand:                    gtroff Output.
* ditroff:                               History.
* geqn:                                  Options.
* gpic:                                  Options.
* grefer:                                Options.
* groff:                                 Options.
* grog:                                  Invocation Examples.
* gsoelim:                               Options.
* gtbl:                                  Options.
* gtroff:                                Options.
* perl:                                  I/O.
* soelim:                                Miscellany.
* troffrc:                               Options.
* troffrc, specifying hyphenation:       Manipulating Hyphenation.


File: groff.info,  Node: Concept Index,  Prev: Program Index,  Up: Top

Concept Index
*************

* Menu:

* access of postprocessor:               Postprocessor Access.
* adjusting:                             Filling and Adjusting.
* adjusting and filling, manipulating:   Manipulating Filling and Adjusting.
* aliases, macro:                        Writing Macros.
* annotations:                           Common Features.
* appending to strings:                  Strings.
* appending, to a macro:                 Writing Macros.
* arc drawing:                           Drawing Functions.
* arguments to requests:                 Request Arguments.
* artificial fonts:                      Artificial Fonts.
* assigning formats:                     Assigning Formats.
* auto-increment:                        Auto-increment.
* baseline:                              Sizes.
* basic units:                           Measurements.
* basics:                                Basics.
* Beagle Brothers:                       I/O.
* blank line:                            Implicit Line Breaks.
* blank lines:                           Manipulating Spacing.
* break:                                 Basics.
* break, implicit:                       Implicit Line Breaks.
* builtin registers:                     Builtin Registers.
* cannibalism:                           Strings.
* capabilities of groff:                 groff Capabilities.
* centering lines:                       Basics.
* centimeter:                            Measurements.
* changing fonts:                        Changing Fonts.
* changing type sizes:                   Changing Type Sizes.
* character pile:                        Drawing Functions.
* character translations:                Character Translations.
* character, control:                    Requests.
* character, hyphenation:                Manipulating Hyphenation.
* characters, creating:                  Using Symbols.
* characters, removing:                  Using Symbols.
* circle drawing:                        Drawing Functions.
* command-line options:                  Options.
* commands, embedded:                    Embedded Commands.
* comments:                              Comments.
* comments, lining up with tabs:         Comments.
* comments, with ds:                     Strings.
* common features:                       Common Features.
* conditionals and loops:                Conditionals and Loops.
* contents, table of:                    Tabs and Fields.
* control character:                     Requests.
* control, page:                         Page Control.
* conventions for input:                 Input Conventions.
* copy-in mode:                          Copy-in Mode.
* copy-in mode, and write requests:      I/O.
* copying:                               Copying.
* creating new characters:               Using Symbols.
* credits:                               Credits.
* current page number:                   Page Layout.
* debugging:                             Debugging.
* default units:                         Default Units.
* differences in implementation:         Implementation Differences.
* dimensions, line:                      Line Layout.
* displays:                              Common Features.
* diversion traps:                       Diversion Traps.
* diversions:                            Diversions.
* double spacing:                        Basics.
* drawing a circle:                      Drawing Functions.
* drawing a polygon:                     Drawing Functions.
* drawing a spline:                      Drawing Functions.
* drawing an arc:                        Drawing Functions.
* drawing an ellipse:                    Drawing Functions.
* drawing functions:                     Drawing Functions.
* drawing horizontal lines:              Drawing Functions.
* drawing vertical lines:                Drawing Functions.
* ellipse drawing:                       Drawing Functions.
* em:                                    Measurements.
* embedded commands:                     Embedded Commands.
* empty line:                            Implicit Line Breaks.
* empty lines:                           Manipulating Spacing.
* en:                                    Measurements.
* end-of-input traps:                    End-of-input Traps.
* environment variables:                 Environment.
* environments:                          Environments.
* escape, width:                         Page Motions.
* escapes:                               Escapes.
* examples of invocation:                Invocation Examples.
* expressions:                           Expressions.
* families, font:                        Font Families.
* features, common:                      Common Features.
* fields:                                Tabs and Fields.
* fields and tabs:                       Tabs and Fields.
* file formats:                          File formats.
* file inclusion:                        I/O.
* files, font:                           Font Files.
* filling:                               Filling and Adjusting.
* filling and adjusting, manipulating:   Manipulating Filling and Adjusting.
* filling, shades of gray:               Drawing Functions.
* floating keep:                         Common Features.
* font families:                         Font Families.
* font file format:                      Font Files.
* font files:                            Font Files.
* font positions:                        Font Positions.
* fonts:                                 Fonts.
* fonts, artificial:                     Artificial Fonts.
* fonts, changing:                       Changing Fonts.
* footers:                               Page Layout.
* footnotes:                             Common Features.
* form letters:                          I/O.
* formats, assigning:                    Assigning Formats.
* formats, file:                         File formats.
* fractional point sizes:                Implementation Differences.
* fractional type sizes:                 Fractional Type Sizes.
* functions for drawing:                 Drawing Functions.
* groff - what is it?:                   What Is groff?.
* groff capabilities:                    groff Capabilities.
* groff invocation:                      Invoking groff.
* GROFF_COMMAND_PREFIX, environment variable: Environment.
* GROFF_FONT_PATH, environment variable: Environment.
* GROFF_TMAC_PATH, environment variable: Environment.
* GROFF_TMPDIR, environment variable:    Environment.
* GROFF_TYPESETTER, environment variable: Environment.
* gtroff output:                         gtroff Output.
* headers:                               Page Layout.
* history:                               History.
* horizontal lines, drawing:             Drawing Functions.
* horizontal space:                      Page Motions.
* hyphenation:                           Hyphenation.
* hyphenation character:                 Manipulating Hyphenation.
* hyphenation, manipulating:             Manipulating Hyphenation.
* i/o:                                   I/O.
* identifiers:                           Identifiers.
* if-else:                               if-else.
* implementation differences:            Implementation Differences.
* implicit breaks of lines:              Implicit Line Breaks.
* implicit line breaks:                  Implicit Line Breaks.
* inch:                                  Measurements.
* including a file:                      I/O.
* incompatibilites with Unix troff:      Implementation Differences.
* increment, automatic:                  Auto-increment.
* input conventions:                     Input Conventions.
* input line traps:                      Input Line Traps.
* inserting horizontal space:            Page Motions.
* interpolating registers:               Interpolating Registers.
* introduction:                          Introduction.
* invocation examples:                   Invocation Examples.
* invoking groff:                        Invoking groff.
* keep:                                  Common Features.
* keep, floating:                        Common Features.
* kerning and ligatures:                 Ligatures and Kerning.
* layout, line:                          Line Layout.
* layout, page:                          Page Layout.
* leaders:                               Tabs and Fields.
* leading:                               Sizes.
* letters, form:                         I/O.
* ligatures and kerning:                 Ligatures and Kerning.
* line break:                            Basics.
* line dimensions:                       Line Layout.
* line layout:                           Line Layout.
* line, blank:                           Implicit Line Breaks.
* line, horizontal:                      Drawing Functions.
* line, implicit breaks:                 Implicit Line Breaks.
* line, vertical:                        Drawing Functions.
* list:                                  Common Features.
* loops and conditionals:                Conditionals and Loops.
* machine units:                         Measurements.
* macro aliases:                         Writing Macros.
* macro packages:                        Macro Packages.
* macro tutorial for users:              Tutorial for Macro Users.
* macros:                                Macros.
* macros, writing:                       Writing Macros.
* major quotes:                          Common Features.
* manipulating filling and adjusting:    Manipulating Filling and Adjusting.
* manipulating hyphenation:              Manipulating Hyphenation.
* manipulating spacing:                  Manipulating Spacing.
* measurements:                          Measurements.
* miscellany:                            Miscellany.
* mode, copy-in:                         Copy-in Mode.
* mode, copy-in, and write requests:     I/O.
* mode, no-space:                        Manipulating Spacing.
* motions, page:                         Page Motions.
* new page:                              Page Control.
* newlines, in strings:                  Strings.
* no-space mode:                         Manipulating Spacing.
* numerals, roman:                       Assigning Formats.
* options:                               Options.
* orphan:                                Page Control.
* output, gtroff:                        gtroff Output.
* page control:                          Page Control.
* page layout:                           Page Layout.
* page location traps:                   Page Location Traps.
* page motions:                          Page Motions.
* page number:                           Page Layout.
* paragraphs:                            Common Features.
* parameters:                            Parameters.
* pica:                                  Measurements.
* pile, character:                       Drawing Functions.
* point sizes, fractional:               Implementation Differences.
* points:                                Measurements.
* polygon drawing:                       Drawing Functions.
* positions, font:                       Font Positions.
* postprocessor access:                  Postprocessor Access.
* postprocessors:                        Postprocessors.
* preprocessors:                         Preprocessors.
* programming tutorial:                  Programming Tutorial.
* quotes, major:                         Common Features.
* ragged-right:                          Manipulating Filling and Adjusting.
* registers:                             Registers.
* registers, builtin:                    Builtin Registers.
* registers, interpolating:              Interpolating Registers.
* registers, setting:                    Setting Registers.
* removing characters:                   Using Symbols.
* request arguments:                     Request Arguments.
* requests:                              Requests.
* roman numerals:                        Assigning Formats.
* sentence spaces:                       Sentences.
* sentences:                             Sentences.
* setting registers:                     Setting Registers.
* shades for filling:                    Drawing Functions.
* sizes:                                 Sizes.
* space, horizontal:                     Page Motions.
* space, vertical:                       Measurements.
* spaces between sentences:              Sentences.
* spacing:                               Basics.
* spacing, manipulating:                 Manipulating Spacing.
* spline drawing:                        Drawing Functions.
* stops, tabulator:                      Tab Stops.
* strings:                               Strings.
* strings, appending:                    Strings.
* summary:                               Summary.
* symbols, using:                        Using Symbols.
* tab stops:                             Tab Stops.
* table of contents:                     Tabs and Fields.
* tabs and fields:                       Tabs and Fields.
* tabs before comments:                  Comments.
* text:                                  Text.
* time:                                  I/O.
* titles:                                Page Layout.
* translations of characters:            Character Translations.
* traps:                                 Traps.
* traps, diversion:                      Diversion Traps.
* traps, end-of-input:                   End-of-input Traps.
* traps, input line:                     Input Line Traps.
* traps, page location:                  Page Location Traps.
* tutorial for macro users:              Tutorial for Macro Users.
* tutorial for programming:              Programming Tutorial.
* type sizes, changing:                  Changing Type Sizes.
* type sizes, fractional:                Fractional Type Sizes.
* units of measurement:                  Measurements.
* units, default:                        Default Units.
* user's macro tutorial:                 Tutorial for Macro Users.
* user's tutorial for macros:            Tutorial for Macro Users.
* using symbols:                         Using Symbols.
* vertical lines, drawing:               Drawing Functions.
* vertical space:                        Measurements.
* warnings:                              Debugging.
* what is groff?:                        What Is groff?.
* while:                                 while.
* width escape:                          Page Motions.
* writing macros:                        Writing Macros.



Tag Table:
Node: Top1764
Node: Copying2270
Node: Introduction21462
Node: What Is groff?21930
Node: What Is groff?-Footnotes23476
Ref: What Is groff?-Footnote-123550
Node: History23587
Node: groff Capabilities27962
Node: Macro Packages29127
Node: Preprocessors29758
Node: Postprocessors31138
Node: Credits31586
Node: Invoking groff31875
Node: Options32807
Node: Environment38904
Node: Invocation Examples40149
Node: Tutorial for Macro Users41212
Node: Basics41644
Node: Basics-Footnotes46195
Ref: Basics-Footnote-146253
Node: Common Features46347
Node: Programming Tutorial52608
Node: Text53494
Node: Filling and Adjusting54008
Node: Hyphenation54740
Node: Sentences55490
Node: Tab Stops56200
Node: Implicit Line Breaks56901
Node: Input Conventions57833
Node: Measurements58627
Node: Default Units60496
Node: Expressions61071
Node: Identifiers62458
Node: Embedded Commands63918
Node: Requests64663
Node: Request Arguments65526
Node: Macros66323
Node: Escapes66677
Node: Comments68091
Node: Comments-Footnotes69710
Ref: Comments-Footnote-169772
Node: Registers69871
Node: Setting Registers70335
Node: Interpolating Registers71185
Node: Auto-increment71445
Node: Assigning Formats72092
Node: Builtin Registers73481
Node: Manipulating Filling and Adjusting74835
Node: Manipulating Hyphenation78675
Node: Manipulating Spacing84227
Node: Tabs and Fields85951
Node: Character Translations88951
Node: Line Layout89942
Node: Page Layout92045
Node: Page Control93687
Node: Fonts95209
Node: Changing Fonts96029
Node: Font Families97891
Node: Font Positions98803
Node: Using Symbols100867
Node: Artificial Fonts104874
Node: Ligatures and Kerning105984
Node: Sizes107031
Node: Changing Type Sizes107859
Node: Fractional Type Sizes109075
Node: Strings111285
Node: Conditionals and Loops113108
Node: if-else114112
Node: while115322
Node: Writing Macros116046
Node: Copy-in Mode117220
Node: Parameters118035
Node: Page Motions119682
Node: Drawing Functions123101
Node: Traps126981
Node: Page Location Traps127654
Node: Diversion Traps129741
Node: Input Line Traps130179
Node: End-of-input Traps130773
Node: Diversions131378
Node: Environments134181
Node: I/O135721
Node: Postprocessor Access139950
Node: Miscellany140878
Node: Debugging142730
Node: Implementation Differences147896
Node: Summary151397
Node: File formats151512
Node: gtroff Output151684
Node: Font Files158267
Node: Request Index165789
Node: Register Index177708
Node: Program Index181981
Node: Concept Index182961

End Tag Table
