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\bf Distributing documents in electronic form:\\
    From \LaTeX{} to WWW, HTML, and Acrobat\\[1mm]
    Nanterre January 19th 1995\\[1mm]
    A report by Michel Goossens
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On Thursday January 19th GUTenberg, the \TeX{} Users Group of the
French speaking community, organized in Nanterre, just outside Paris
(merely a 15 minute ride from the center of Paris on the RER, the
underground express network).  The venue was in a nice and modern
setting, a huge fitness club with several tennis courts, a swimming
pool, a large restaurant, and good conference facilities.

More than 140 participants assembled at 9:30 in the larger conference
room, where I spoke a few words of welcome, emphasizing the importance
of the latest developments in electronic publishing that were the
subject of the day's presentations and the fact that the \TeX{}
community must try and use these new possibilities to its advantage,
rather than letting itself be overtaken by them.  I also took the
opportunity to thank Jacques Andr\'e and Christian Rolland, and their
colleagues of Rennes for the excellent way they had organized the
meeting and prepared the 160-page issue of the Cahiers\footnote{% One
can order this regular issue (number 19 of the Cahiers) for the sum of
20 USD, postage included, by sending a cheque or money order to
address: GUTenberg, BP 10, F~93220 Gagny Principal.  Note, however,
that all articles are in French.}  containing the written-up text
corresponding to all presentations, so that each participant could
receive a copy.

The general framework for the day was set by the first speaker, Luc
Ottavj (INRIA Sophia-Antipolis), who gave an introduction to the
structure of the Internet, its media, protocols, services, and rules.
He stated the important fact that most of the research activities of
the world now take advantage of the presence of this network, mainly
because for the first time in the history of mankind data can be
freely and (almost) instantaneously exchanged between any two
individuals who decide to be connected to the Internet.  He also
emphasized that the success of the Internet with its over 30 million
connections today is largely due to its strict adherence to standards
that are adopted using simple, open and efficient procedure.  Finally
he reviewed a few of the more common tools for information exchange,
WAIS, Gopher, and, of course, WWW.

The next two talks, given by myself, dealt with the SGML language, and
its incarnation in HTML2 (the present version).  After showing why
SGML is an important step in the development of tools for easing the
re-use of document sources for multiple purposes, I presented the
advantages of SGML's (and \LaTeX's) generic approach in document
markup. The use of SGML consists essentially of two main stages, the
first being the definition of the structure of the document class, its
elements and their attributes, etc. This is the work of a specialist
and is codified in the DTD (Document Type Definition). In the second
stage the elements defined in the DTD are used to mark up the various
documents belonging to the class in question.  Using the example of
the DTD of the HTML2 language the syntax of the various elements that
can be encountered in a DTD were discussed, so that users of HTML can
more easily understand the relation between the various element names,
entities and attribute keywords.

Some basic knowledge about the DTD is also required when one wants to
use SGML tools, that validate an SGML document, like \texttt{sgmls}, a
publicly available SGML parser, that reads the document's DTD before
checking a document for correctness. It is extremely important, if one
wants to use SGML/HTML editors that documents are more or less
correct.  The HTML browsers that are commonly used (like Mosaic) are
way too tolerant in that they just ignore invalid tags, so giving the
impression that documents, that can be viewed by a browser, are indeed
valid.  It is therefore important to check documents first, to make
their maintenance and understanding easier, and to ensure that they
will be treated correctly by all browsers. In the absence of Christian
Rolland, I then presented the syntax of the HTML2 markup language,
which is at present the standardized language used and understood by
all WWW/HTML hypertext browsers.  Using the principle of teaching by
example, short code fragments and their resulting visual appearance
gave the audience a the possibility to get an idea of the flavor of
the source format of the language.  Special attention was drawn to the
hypertext elements of the language, that specifically allow one to
link different documents via the URL (Universal Resource Locator)
mechanism and the notion of anchor and its various attributes were
explained in detail.

After Coffee the following speaker, Fran\c{c}ois Dagorn (Rennes),
discussed the important subject of electronic forms in HTML.  They
allow a communication between the user and the machine serving the
document.  With the help of a detailed example he showed how the
standard CGI (Common Gateway Interface) interface defines the rules
that must be followed to write and execute action procedures (CGI
scripts).  He showed that handling these scripts is not completely
trivial, the main problem being that the verification and decoding of
the information in the different fields of the form must be completely
treated by the programmer.  He also discussed clickable maps, that
provide a user-friendly interface to graphical information. He pointed
out, however, that this facility should be used with care since the
browser does not know how the image is segmented, so that the user has
in general no precise visual indication about where he should click.

Just before lunch Vincent Quint (INRIA) described the experience of
his group with generating hypertext documents for WWW.  As many users
prepare their document themselves they must introduce the HTML tags by
hand, and this is often an error-prone process, not only because the
authors do not always understand the exact structure of the DTD, but
also since most editors offer very little (or no) help to verify the
correctness of the HTML source.  Some users might prefer to mark up
their documents in a system they know better (Word, FrameMaker,
\LaTeX), and then use filters to translate their documents into HTML.
This has the disadvantage that those systems do not include any
knowledge about WWW and its hypertext possibilities, so that they must
be added by hand.  Since both these approaches have severe drawbacks,
the speaker presented a solution based on the structured document
editor Grif.  The Grif editor has been extended to take into account
the hypertext and hyperlink possibilities of WWW.  Since Grif contains
a formatted and very readable presentation window of the source, even
for complex elements, such a forms, it offers a user-friendly
environment to create WWW documents,

After lunch all talks discussed applications, and I had the pleasure
to start by presenting tools to translate from \LaTeX{} to HTML (and
the reverse). Since \LaTeX{} and HTML are both generic markup
languages, a lot of structural similarities exist and these can be
exploited to translate between them.

By far the more complete tool that transforms \LaTeX{} into HTML is
Nikos Drakos' \texttt{latex2html}, and I discussed that program
written in \texttt{perl} in detail.  It was shown, with the help of an
example, how simple it is to translate ``standard'' \LaTeX{}
documents.  The basic principle underlying the \texttt{latex2html}
approach is that everything that has no equivalent in HTML is fed
through to \LaTeX{} and transformed into a (gif) bitmap, that can be
viewed on a graphics screen by Mosaic (or other) browsers.  This
approach guarantees that the complete input document can be rendered
correctly.  As the program is written in \texttt{perl}, one can add
one's own definitions for certain commands, so that the use has
complete control on the way \LaTeX{} commands and environments are
handled.  Moreover, several hypertext extensions allow explicit
cross-document references in the \LaTeX{} source, so that it becomes
really easy to obtain HTML documents that are correctly linked.  At
the end I also spent a few minutes on the \texttt{html2latex} and
\texttt{sgml2tex} tools, that take the reverse direction, translating
HTML documents into \LaTeX{}.  This is sometimes desired if nicely
printed output from an HTML source is needed.

The second speaker of the afternoon, Philippe Louarn (Irisa/Inria
Rennes), then showed us a real-life example of preparing a large HTML
document from \LaTeX{} sources.  He discussed the 1993 Inria Activity
Report that is a combination of many \LaTeX{} source files written by
about 100 different groups of research staff from all over France.  In
its final form it counts about 2000 pages in 7 printed volumes.  Last
year it was decided to make the report available on WWW, and SGML was
chosen as the interchange language for the master source.  As most
contributions were originally written in \LaTeX{} they were first
translated into SGML.  Different presentation formats were obtained
from the SGML source by using application programs that generated
PostScript (printing), HTML (for WWW), Ascii (ftp, minitel),
distribution (\LaTeX), etc.  A special DTD was developed and Grif was
used as SGML editor.  To eliminate the initial \LaTeX{}-to-SGML
translation phase the next logical step would be to convince the users
to use Grif directly to enter their documents, and this idea is being
actively pursued.

The final presentation was by Yannis Haralambous (Lille).  He showed
how hypertext and good typography can live together via \LaTeX{} and
Acrobat.  By using the existing cross-reference capabilities of
\LaTeX{} and a specially written package \texttt{hyperref} the
necessary information for handling the cross-references by Acrobat,
are written into the DVI file. The program \texttt{dvihps}, a special
version of Rokicki's \texttt{dvips} program, then transforms the DVI
file into PostScript, and the latter is transformed into a pdf
(Adobe's Portable Document Format) file with Adobe Distiller.  The pdf
file that is obtained has the table of contents, list of tables and
figures, and all (\LaTeX) label, ref, and citation commands as active
elements, that allow one to navigate through the document by merely
clicking on them. This means that one can take an existing \LaTeX{}
document, add one extension (\texttt{hyperref}), rerun through
\LaTeX{}, transform into (hyper)PostScript with \texttt{dvihps}, and
after distilling one obtains a document that has all navigation
possibilities present in the source document.  It was mentioned that
the \texttt{ghostscript} (\texttt{gs}) program will soon be able to
view pdf files, so that these hypertext facilities will become
available on all platforms where \texttt{gs} is installed.  It is even
rumored that Alladin software, the developers of \texttt{gs}, is
thinking about offering by ``next Christmas'' a version of
\texttt{ghostscript} that will distill PostScript programs.  It is
always nice to dream.

The day was brought to an end by a round table discussion about the
possible influence on these technologies on publishing industry.  It
was felt that these new hypertext techniques would not replace the
existing processors, like Word, FrameMaker or \LaTeX{}, but rather
complement them, since it is important that users should use the tools
they feel most comfortable with.  SGML will almost certainly emerge as
the format in which information will be stored, with source entering
systems providing back ends for SGML. Various filters will allow SGML
sources to be (re)used for multiple purposes.  It was also emphasized
that most hypertext viewing systems are still hampered by poor display
qualities (mostly 100dpi on rather small screens), so that it will
certainly take quite some time before typographic quality similar to
the one reached on the printed page will become widely available,
although the developments around Acrobat are already a step in the
right direction.  And the paper book is certainly not dead yet, since
it will probably not be tomorrow that one will read a detective story
on a computer screen in bed, or a poem on a laptop on the beach.
Another point was the basic distinction between the linearity of the
book-printing paradigm and the parallel multi-dimensional view needed
when preparing data for hypertext media.  Tools which clearly show the
hyper-structure of documents are only now becoming available but will
play an ever-increasing role in preparing hypertext documents by
allowing to link their components graphically.

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