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<div xmlns="http://www.tei-c.org/ns/1.0" xml:id="chap-intro"><!-- revised $Date$ -->
<head>Introduction to text markup</head>
<opener>
<!-- what this chapter is about -->
</opener>
<p></p>
<div>
<head>Introduction</head>
<p>This book shows you how to combine two powerful technologies
— TEI and XML — wide variety of everyday writing,
publishing, and research tasks.
It gives detailed guidance in the use of XML to solve
real world problems, using as its basis the
<title>Recommendations</title> of the Text Encoding Initiative. It
also discusses and exemplifies freely-available tools you can use to
produce TEI texts and publish them on the web and in
print.
</p>
<p>
The Text Encoding Initiative (TEI) is a major scholarly project which
has published definitive markup guidelines for text material across a
very broad range of materials. Its recommendations have been taken up
by academic researchers, digital libraries and language engineering
projects across the world. This book makes the
<title>Guidelines</title> accessible and usable for the individual
author and academic by providing authoritative coverage and practical
explication for key parts of the published Recommendations.
</p>
<p>XML is the technology underlying the latest developments on the
World Wide Web and the information revolution. Understanding how to
use XML is essential to the information professional, as is keeping up
with the rapid proliferation of specialist application languages built
upon it. This books helps a non-specialist user community share in
that revolution by describing how the facilities of XML can
best be exploited for specific purposes.
</p>
<p>The book has three parts:
<list type="ordered">
<item>An introductory section, containing short overview chapters,
each of which gives a brief summary of key issues and general principles
</item>
<item>A suite of detailed use cases, each of which presents the reader
with a specific application scenario, and shows how to address it
using TEI and XML. Each case may be studied in isolation but they are
of increasing technical sophistication and complexity. Together they
provide reasonably complete coverage of the key parts of TEI and the
full range of XML facilities.
</item>
<item>A reference section, containing more detailed technical
information about the systems described in the book.
</item>
</list>
</p>
<p>It may be helpful to point out what the book does <emph>not</emph> aim to
do:
<list type="unordered">
<item>It does not teach XML syntax, how to write XML DTDs or
schemas </item>
<item>It does not provide detailed reference material about the XML family of standards
</item>
<item>It does not discuss schemas other than those of the TEI. </item>
</list>
</p>
</div>
<div>
<head>The intended audience</head>
<p>The book is intended for people
who have learnt something about XML and are
considering using it for their work, but are not sure how to apply it,
in particular which tag set to use. A typical reader will probably
have produced an HTML web page or written an article using LaTeX, and
will have some degree of technical experience beyond simply using a
word-processor. The book does not assume any knowledge of computer
programming, but readers who are unfamiliar with scripting languages
may find some of it technical.
</p>
<p>The general principles we discuss are widely applicable, as are the
techniques we propose. However, both the specific scenarios discussed
and the working environment we assume mean that the book is likely to
be of most use in academic or similar environments. The material is not
intended to appeal to e.g. technical authors in the aerospace
industry, or those using XML for healthcare records.
</p>
</div>
<div>
<head>Basic principles of this book</head>
<p>This book tells you how to make electronic texts and do useful
things with them. It is intended to be entirely practical, and is
arranged as a series of realistic scenarios.
We make a few fundamental assumptions about all the projects we describe:
<list type="unordered">
<item>We use XML for <emph>all</emph> aspects
of the work. That is not to say that software such as a database may
not sometimes be the best way to collect and store some of the information, but
we always describe an XML-only solution. This ensures that
material can always be interchanged and stored in a simple
format.</item>
<item>We describe software which conforms to the principles of the
Open Source movement and the Free Software Foundation. All the
techniques in this book can be implemented without using proprietary
closed software systems.
</item>
<item>We implement all our solutions using the principles of the
Text Encoding Initiative. That is not to say that every XML element
we describe is listed in the TEI DTD; we use the TEI
DTD where it is appropriate, but extend the TEI (using the principles
described in the TEI Guidelines<ptr rend="citeparen"
target="TEIGuide"/>) where we need to.</item>
</list></p>
</div>
<div><head>What is XML?</head>
<p>A section of this length is not the place from which to learn the
details of XML and its TEI implementation<note place
="foot">Fortunately there is no shortage of introductory material on
such topics on the Web: the TEI's own <soCalled>Gentle
Guide</soCalled> is at <ptr
target="http://www.tei-c.org/P4X/SG.html"/></note>. However, it may be
helpful for the complete novice to mention some of the salient
features of this way of thinking about what a document is.</p>
<p>In an XML document, information is represented by means of
identifiable objects, called elements. The document itself is such an
object, and it contains within it nested occurrences of other objects
of the same or other types. Objects of any type may also bear
descriptive named attributes. A very simple document
might consist of a <gi>text</gi> element, containing a number of <gi>div</gi>
elements. Each <gi>division</gi> element might begin with an optional
<gi>head</gi>, and then contain a number of <gi>p</gi> elements. Each
<gi>p</gi> might contain just plain text, and might have an attribute
<ident>lastChange</ident> specifying the time and date it was last changed.</p>
<p>An important characteristic of an XML document is that its structure can be
described by means of a textual grammar (technically known as a
schema). A schema specifies both what elements exist, and how they can
meaningfully be combined (for example, that a <gi>div</gi> element may
contain a <gi>head</gi> only if it precedes a <gi>p</gi>). Depending on
the specific schema language employed, rules may also be specified
which constrain the legal values for attributes, for example to
specify exactly the format for representing dates and times. </p>
<p>Every XML document is modelled as a single hierarchy of elements,
which means that it can easily be represented as a linearised sequence
with labelled brackets. So, for example, by marking the start and end
of texts, divisions, headings, and paragraphs, the nested structure
in figure 2
below can be represented by the linear sequence given in
figure 3 without loss of information.</p>
<!--
<figure><graphic url="boxes.png" width="3in"/></figure>
-->
<egXML xmlns="http://www.tei-c.org/ns/Examples"><text><div>
<head>Heading</head>
<p>Para 1</p>
<p>Para 2</p>
</div></text></egXML>
<p>This tree-based model of textual structure has many advantages from
both conceptual and processing points of view. However, it is
important to note that one can often define more than one hierarchic
structure within a text and moreover that the components of such
structures rarely map tidily onto one another. A codex may be seen as a
hierarchic structure of gatherings containing leaves, each comprising a
recto page and a verso page. A page may contain many paragraphs, but
a single paragraph may start on one page and finish on the next. We
cannot therefore easily nest a paragraph hierarchy within a page
hierarchy. Similarly, in a verse drama, because we can expect to find
verse lines which are divided between speakers, we cannot easily
combine speaker and metrical structures. A number of techniques have
been proposed for the representation of such structures in XML, but
of which the majority depend on the language's ability to represent
links between one point of a structure and another, thus making it
possible to define one or more independent hierarchies while at the
same time representing their points of alignment, both with each other
and with a single segmentation of the text being annotated.</p>
<p>XML markup thus provides a unified way of representing individual
tokens in a text, the structural units in which they occur, arbitrary
regions of text, and links, correspondences, or alignment amongst
these elements. These features of a text can also be formally verified
against a textual grammar. XML markup can be verified in such a way as
to ensure that it reflects the meaning of your data, not its
appearance</p>
</div>
<div><head>What is the TEI?</head>
<p>In November 1987, representatives from about forty academic
institutions and projects converged on Vassar College, Poughkeepsie in upstate New
York. They shared a common vision: the transformation of substantial
amounts of the world's literature into computer-readable form; but
what had brought them together was the lack of agreed international
standards in the production of what was at that time called
<soCalled>machine-readable text</soCalled>. Over two wintry days, they
considered the cacophony of different practices emerging in the
service of that common vision at institutions already existing across
the US, across Europe, and in Japan, but scattered and fragmented in
those pre-World Wide Web days. The Internet as a social phenomenon was
approaching adolescence: it had not yet established itself outside the
world of academic research, and the technical standards needed to move
it forward were still only dimly perceived. </p>
<p>Following that conference<note place="foot">For a report on the
outcomes of the Poughkeepsie Conference, see <title level="a">Report
of Workshop on Text Encoding Guidelines</title> in <title
level="s">Literary & Linguistic Computing</title>, 3
(1988)</note>, the Text Encoding Initiative (TEI) was formed as an
international research project, with funding from the US National
Endowment for the Humanities, the European Union, the Canadian Social
Science Research Council, and the Andrew W Mellon Foundation. The TEI
was jointly sponsored by three established international professional
associations, which established a small management committee, and
appointed two <soCalled>editors</soCalled> to co-ordinate the
enthusiastic participation of more than a hundred scholars
worldwide. Its remit was to attempt a complete definition of current
practice and to produce recommendations or Guidelines for the creation
and usage of electronic texts in key linguistic and literary
disciplines. The first research phases of the TEI came to an end in
1994 with the publication of TEI P3, the <soCalled>big green
books</soCalled> which over the next few years were to become the
reference standard for the building of the digital library<note
place="foot">For history and background on the TEI, see the website at
<ptr target="http://www.tei-c.org"/></note>.</p>
<p>At the start of the current century, the TEI re-established itself
as a membership consortium, jointly hosted by two US and two European
Universities, and sponsored a first major revision of the TEI
<title>Guidelines</title>. This edition, known as TEI P4, was a
<soCalled>maintenance release</soCalled>, bringing the Guidelines up
to date with changes in the technical infrastructure — most notably
in the use of the W3C's Extensible Markup Language (XML) as its means
of expression<note place="foot">This was particularly appropriate in
that one of the editors of the XML standard, Michael Sperberg-McQueen,
had also served as editor of the original TEI Guidelines.</note>
rather than the ISO standard SGML. TEI P4 was published in 2002, under
the imprint of the University of Virginia Press, and forms the current
reference standard.</p>
<p>However, nothing written in digital form is ever really
finished. Since 2002, work has been proceeding on the next major
revision of the TEI Guidelines, to be known as TEI P5, which will
include far more substantive changes than were needed for P4<note place="foot">A
preliminary release of TEI P5 appeared in January 2005: see <ptr
target="http://www.tei-c.org/P5"/> for its current status</note>. </p>
<p>The goals of the TEI were to facilitate better interchange and
integration of scholarly textual data, in all languages, and from all
periods. As such the TEI had two inherently contradictory objectives:
on the one hand, to deliver <soCalled>guidance for the
perplexed</soCalled> by suggesting <emph>what</emph> textual features
should be encoded in a document; on the other, to provide assistance for
the specialist by suggesting <emph>how</emph> any particular set of
textual phenomena might be encoded. Its aim was thus to be both a
user-driven codification of existing best practice, and also a loose
framework into which unpredictable extensions might be fitted. Its
recommendations thus cover both generic text structures and some
highly specific areas based on (but not limited by) existing
practice.</p>
<p>The original scope of the TEI was encyclopaedic, embracing not just
the basic structural and functional components of running text but
also diplomatic transcription of non-digital textual (and aural)
sources, images, and annotation thereof; links, correspondence, and
alignment of encoded objects; data-like objects such as dates, times,
places, persons, events (what is now termed <soCalled>named entity
recognition</soCalled>); meta-textual annotations (correction,
deletion, etc); linguistic analysis of all kinds and at all levels;
contextual metadata of all kind. No-one requires all of this, yet all
of it is required by someone. Considerable effort and ingenuity was
therefore invested in ways of making it possible to derive multiple
views (DTDs or schemas) from the enormous set of textual categories or
distinctions identified by the Guidelines, which (as of TEI P4)
documented 362 distinct XML elements, 95 attributes, and 88 classes,
grouped into 24 distinct modules of various kinds. To
demonstrate that this polymorphic architecture actually worked, the
TEI editors used it to produce TEI Lite, one specific customization
which turned out to have a life of its own. </p>
<p>TEI Lite was intended to meet three goals. The first was to provide
a subset of the TEI Recommendations which would be adequate to the
needs of most likely users of the whole of the TEI most of the
time. The second goal was to provide a subset of elements rich enough
to support an authoring environment for the production of online
documentation such as the Guidelines themselves. And, as already
mentioned, TEI Lite was conceived of as a practical demonstration of
the customization facilities of the TEI scheme — and therefore had to
provide some features which were <emph>not</emph> otherwise included
in it.</p>
<p>Despite the protestations of the TEI editors and others, however,
TEI Lite was occasionally perceived as being <emph>the</emph>
recommended introduction to the TEI scheme for all purposes. Widely
translated, its manual came to form the basis of many introductory
tutorials and workshops<note place="foot">See <ptr
target="http://www.tei-c.org/Lite/"/></note>, as well as to define the
practice of many major encoding projects, particularly in the digital
library community. This was a mixed blessing: TEI Lite is (inevitably)
lacking in elements some projects will consider essential, and (even
more inevitably) over-supplied with elements other projects will never
wish to use. Because the customization methods by which TEI Lite was
constructed remain somewhat arcane to the non-SGML specialist, there
was a tendency for projects to edit TEI Lite itself in nonstandard and
unpredictable ways to produce <soCalled>TEI Lite like</soCalled>
schemas, thus seriously compromising the interchangeability of their
resources. More worryingly, it came to be perceived in some quarters
as the TEI's final word on what <soCalled>text</soCalled>
<emph>really</emph> is: though any careful reading of the TEI
Guidelines proper would show the extent to which the TEI tries to
problematize this notion, by emphasizing the relativity of the shared
assumptions and priorities about the digital agenda which underly its
suggestions. Those priorities, specifically the focus on content and
function (rather than presentation), and the identification of generic
solutions (rather than application-specific ones) have stood the test
of time. But they are not necessarily universal.</p>
<p>All texts are alike, in some sense; yet every text is
different. Because it needed to be able to cope with the full variety
of texts and textual readings, and the whole range of scholarly
endeavours, the TEI system was designed in a modular way. Rather than
define a single monolithic schema, the TEI defines a number of schema
modules which can be combined in a controlled manner. Each module
contains definitions for a set of elements and attributes, each of
which is also a member of one or more classes. Elements may refer to
each other indirectly by means of their class membership. This allows
the system designer to modify particular components of a module, or to
add new components to it, without disturbing the rest of the
structure. The technical details of the mechanisms used to implement
this architecture are described elsewhere<note place="foot">For TEI
P4, see for example <title level="a">Rolling your own with the
TEI</title> in <title level="s">Information Services and Use</title>
vol 13 no 2 (Amsterdam, IOS Press, 1993); for P5, see Sebastian Rahtz,
<title level="a">Converting to schema: the TEI and RelaxNG</title>.
Available from <ptr
target="http://www.idealliance.org/papers/dx_xmle02/papers/03-03-08/03-03-08.html"/>.
Paper presented at XML Europe 2002, Barcelona, May 2002; see also
Burnard and Rahtz, <title level="a">RelaxNG with Son of ODD</title>,
Available from <ptr
target="http://www.mulberrytech.com/Extreme/Proceedings/html/2004/Burnard01/EML2004Burnard01-toc.html"/>.
Paper presented at Extreme Markup Languages, Montréal, August
2004</note>; the key point is that the system can be used to develop a
schema which contains all and only the elements and attributes needed
to support the specific needs of a given text-creation project without
overly compromising the interchangeability of the project's
deliverables.</p>
</div>
<closer>
<!-- what we learnt in this chapter-->
</closer>
</div>