# Future LaTeX and SGML


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The LaTeX3 Project

Copyright 1995--1997 Frank Mittelbach and Chris Rowley

10 May 1997

the LaTeX3 Project, which was established to produce a new version
of LaTeX, the widely-used and highly-acclaimed document
preparation system.  It also describes how you can help us to
achieve our aims.

For Archive maintainers, Authors, Publishers and
Distributors
The project team request that, whenever possible, you include this
article in any of the following:

* Books about TeX and LaTeX.
* Instructions for authors on using LaTeX.
* The printed documentation of CD-ROM collections that contain
LaTeX.
* On-line collections that include a significant proportion of
documents encoded in LaTeX.

Outline

The purposes of the LaTeX3 system can be summarized thus: it will
greatly increase the range of documents which can be processed; and it
will provide a flexible interface for typographic designers to easily
specify the formatting of a class of documents.

The LaTeX3 Project Team is a small group of volunteers whose aim is
to produce this major new document processing system based on the
principles pioneered by Leslie Lamport in the current LaTeX.

The major work of the team before 1997 was the release and
maintenance of the current /standard/ version of LaTeX: the one
you have just acquired.  They will continue to maintain this system,
releasing updated versions every six months and recording these
activities in the LaTeX bugs database (see below).

Although LaTeX may be distributed freely, the production and
maintenance of the system does require expenditure of reasonably large
sums of money.  The LaTeX3 Project Fund has therefore been set up to
channel money into this work.  We know that some users are
aware of this fund as they have already contributed to it---many
thanks to all of them!  If you want to know more about how you can
help the project, see Page \pageref{fund}---and thanks in advance for

Background

With TeX, Knuth designed a formatting system that is able to
produce a large range of documents typeset to extremely high quality
standards. For various reasons (e.g.  quality, portability, stability
described as a world-wide de facto standard for high quality
typesetting. Its use is particularly common in specialized areas, such
as technical documents of various kinds, and for multi-lingual
requirements.

The TeX system is fully programmable. This allows the development
of high-level user interfaces whose input is processed by TeX's
interpreter to produce low-level typesetting instructions; these are
input to TeX's typesetting engine which outputs the format of each
page in a device-independent page-description language.  The LaTeX
system is such an interface; it was designed to support the needs of
long documents such as textbooks and manuals. It separates content and
form as much as possible by providing the user with a generic (i.e.
logical rather than visual) mark-up interface; this is combined with
style sheets which specify the formatting.

Recent years have shown that the concepts and approach of LaTeX are
now widely accepted. Indeed, LaTeX has become the standard method
of communicating and publishing documents in many academic
disciplines.  This has led to many publishers accepting LaTeX
source for articles and books; and the American Mathematical Society
now provides a LaTeX package making the features of AmSTeX
available to all users of LaTeX.  Its use has also spread into many
other commercial and industrial environments, where the technical
qualities of TeX together with the concepts of LaTeX are
considered a powerful combination of great importance to such areas as
corporate documentation and publishing.  This has also extended to
on-line publishing using, for example, PDF output incorporating
hypertext and other active areas.

With the spreading use of SGML-compliant systems (e.g.  Web-based
publishing using HTML or XML) TeX again is a common choice as
the formatting engine for high quality typeset output: a widely used
such system is /The Publisher/ from ArborText, whilst a more
recent development is the object-oriented document editor Grif.  The
latter is used for document processing in a wide range of industrial
applications; it has also been adopted by the Euromath consortium as
the basis of their mathematician's workbench, one of the most advanced
of the emerging project-oriented user environments.  Typeset output
from SGML-coded documents in these systems is obtained by
translation into LaTeX, which will therefore soon also be a natural
choice for the output of DSSSL-compliant systems.

Because a typical SGML Document Type Definition (DTD) uses concepts
similar to those of LaTeX, the formatting is often implemented by
simply mapping document elements to LaTeX constructs rather than
directly to raw TeX'.
This enables the
sophisticated analytical techniques built into the LaTeX
software to be exploited; and it avoids the need to program in TeX.

Motivation

This increase in the range of applications of LaTeX has highlighted
certain limitations of the current system, both for authors of
documents and for designers of formatting styles.

In addition to the need to extend the variety of classes of document
which can be processed by LaTeX, substantial enhancements are
necessary in, at least, the following areas:

* the command syntax (attributes, short references, etc);
* the layout specification interface (style design);
* the level of robustness (error recovery, omitted tags);
* the extendibility (package interface);
* the layout specification of tabular material;
* the specification and inclusion of graphical material;
* the positioning of floating material, and other aspects of page
layout;
* the requirements of hypertext systems.

Further analysis of these deficiencies has shown that some of the
problems are to be found in LaTeX's internal concepts and design.
This project to produce a new version therefore involves thorough
research into the challenges posed by new applications and by the use
of LaTeX as a formatter for a wide range of documents, e.g.  SGML
documents; on-line PDF documents with hypertext links.

This will result in a major re-implementation of large parts of the
system.  Some of the results of such rethinking of the fundamentals
are already available in Standard LaTeX, notably in the following
areas:

* Font declaration and selection;
* Font and glyph handling within mathematical formulas;
* Handling multiple font glyph encodings within a document;
* Allowing multiple input character encodings within a document;
* A uniform interface for graphics inclusion;
* Support for coloured text;
* Building and interfacing new classes and extension packages.

Description}

The strengths of the present version of LaTeX are
as follows:

* excellent standard of typesetting for text, technical
formulas and tabular material;
*  separation of generic mark-up from visual formatting;
*  ease of use for authors;
*  portability of documents over a wide range of platforms;
*  reliable support and maintenance by the LaTeX3 project team.

These will be preserved and in many cases greatly enhanced by the new
version which is being developed to fulfill the following requirements.

* It will provide a syntax that allows highly automated translation
from popular SGML DTDs into LaTeX document classes (these
will be provided as standard with the new version).

The syntax of the new LaTeX user-interface will, for example,
support the SGML concepts of entity', attribute' and short
reference' in such a way that these can be directly linked to the
corresponding  SGML features.

* It will support hypertext links and other features required for
on-line structured documents using, for example, HTML and XML.

* It will provide a straightforward style-designer interface to support
both the specification of a wide variety of typographic requirements
and the linking of entities in the generic mark-up of a document to
the desired formatting.  These two parts of the design process will
be clearly separated so that it is possible to specify different
layouts for the same DTD.

The language and syntax of this interface will be as natural as
possible for a typographic designer.  As a result, this language
could easily be interfaced to a visually-oriented, menu-driven
specification system.

This interface will also support DSSSL specifications and
style-sheet concepts such as those used with HTML and XML.

* It will provide an enhanced user-interface that allows expression of
the typesetting requirements from a large range of subject areas. Some
examples are listed here.

* The requirements of technical documentation (e.g.  offset layout,
change bars, etc).
* The requirements of academic publishing in the humanities
(critical text editions, etc).
* The requirements of structural formulas in chemistry.
* Advanced use of the mathematical-typesetting features of TeX.
* The integration of graphical features, such as shading,
within text.
* the integration of hypertext and other links in on-line
documents using systems such as HTML, XML and PDF.

Special care will be taken to ensure that this interface is
extensible: this will be achieved by use of modular designs.

*  It will provide a more robust author-interface. For example,
artificial restrictions on the nesting of commands will be removed.
Error handling will be improved by adding
a more effective, interactive help system.

*  It will provide access to arbitrary fonts from any family (such as
the PostScript and TrueType fonts) including a wide range of fonts for
multi-lingual documents and the specialist glyphs required by
documents in various technical and academic areas.

*  The new interfaces will be documented in detail and the
system will provide extensive catalogues of examples, carefully
designed to make the learning time for new users (both designers and
authors) as short as possible.

*  The code itself will be thoroughly documented and it will be
designed on modular principles.  Thus the system will be easy to
maintain and to enhance.

The resulting new LaTeX will, like the present version,
be usable with any standard
TeX system and so will be freely available on a wide range
of platforms.

LaTeX documentation}

A complete description of Standard LaTeX can be found in:

*[LaTeX: A Document Preparation System]
Leslie Lamport, Addison Wesley, 2nd ed, 1994.
*[The LaTeX Companion]
Goossens, Mittelbach and Samarin, Addison Wesley, 1994.

A recent addition to the publications closely associated with the
project is:
\begin{citations}
*[The LaTeX Graphics Companion]
Goossens, Mittelbach and Rahtz, Addison Wesley, 1997.
\end{citations}

This LaTeX distribution comes with documentation on several aspects
of of the system.  The newer features of the system are described in
the following documents:
\begin{citations}
*[LaTeXe for authors]
describes the new features of LaTeX documents,
in the file \texttt{usrguide.tex};
*[LaTeXe for class and package writers]
describes how to produce LaTeX classes and packages,
in the file \texttt{clsguide.tex};
*[LaTeXe font selection]
describes the new features of LaTeX fonts for
class and package writers,
in the file \texttt{fntguide.tex}.
\end{citations}

For further contacts and sources of information on TeX and
LaTeX, see the addresses on Page~\pageref{contacts}.

\endgroup
\pagebreak

The LaTeX3 Project Fund}
\label{fund}

No money from this fund has gone towards salaries but there
are many necessities that do need financing: examples are new, or
enhanced, computing equipment and travel to team meetings (the
volunteers come from many different countries, so getting together
occasionally is a non-trivial exercise).

This is why we are appealing to you for contributions to the fund.
Any sum will be much appreciated; the amount need not be large as
small contributions add up to very useful amounts.  Contributions of
suitable equipment and software will also be of great value.  This
appeal is both to you as an individual author and to you as a member
of a group or as an employee: please encourage your department or your
employer to contribute towards sustaining our work.

We should like to see funded projects that make considerable use of
LaTeX (e.g.  conferences and research teams who use it to publish
their work, and electronic research archives using it) include
contributions to this fund in their budgets.  %% e-print systems

We are also asking commercial organisations to assess the benefits
they gain from using, or distributing, a well-supported LaTeX and
to make appropriate contributions to the fund in order that we can
continue to maintain and improve the product.  If you work for, or do
the relevant people the existence and needs of the project.

In particular, we ask that all the large number of organisations and
businesses that distribute LaTeX, within other software or as part
LaTeX at a level that enables them to make regular donations to the
fund from the profit on these items.  We also ask all authors and
publishers of books about LaTeX to consider donating part of the
royalties to the fund.

Contributions should be sent to one of the following addresses:

TeX Users Group, P.O. Box 1239, Three Rivers, CA~93271-1239, USA
Fax:~+1~209~561~4584 Email: tug@mail.tug.org

UK TUG, 1 Eymore Close, Selly Oak, Birmingham B29~4LB, UK
Fax: +44 121 476 2159 Email: uktug-enquiries@tex.ac.uk

Cheques should be payable to the user group (TUG or UKTUG) and be
clearly marked as contributions to the LaTeX3 fund.
Many thanks to all of you who have contributed in the past and thanks

Contacts and information}

on the World Wide Web at:
http://www.tex.ac.uk/CTAN/latex/

pointers to other LaTeX resources, such as the user guides, the
TeX Frequently Asked Questions, and the LaTeX bugs database.

More general information, including contacts for local User Groups,
can be accessed via:
http://www.tug.org/

The electronic home of anything TeX-related is the Comprehensive
TeX Archive Network (CTAN).  This is a network of cooperating ftp
sites, with over a gigabyte of TeX material:
ftp://ftp.tex.ac.uk/tex-archive/
ftp://ftp.dante.de/tex-archive/