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+ Page 5 +

Price-Wilkin, John.  "A Gateway Between the World-Wide Web and
PAT: Exploiting SGML Through the Web."  The Public-Access
Computer Systems Review 5, no. 7 (1994): 5-27.  To retrieve this
file, use the following URL: gopher://info.lib.uh.edu:70/
Or, send the following e-mail message to listserv@uhupvm1.uh.edu:

1.0  Introduction

The HyperText Markup Language (HTML) used by the World-Wide Web
has limited markup and structure recognition capabilities.  Only
a small set of text characteristics can be represented, and few
of these have any functional value beyond display capabilities.
The HTML ANCHOR element supports hypertext links; however, it
cannot retrieve components of a linked document, such as a single
glossary entry from a collection of several thousand entries,
without resorting to programs external to HTML and the Web
server.  In spite of these limitations, HTML and the Web are key
technologies for libraries.
     The Standard Generalized Markup Language (SGML) is a full-
featured, standard markup language.  HTML is actually an SGML
Document Type Definition.  Ideally, it would be possible to
retrieve text documents marked up with the richer SGML tag set
via the World-Wide-Web.
     This technical paper discusses how the Web can be linked to
the PAT system, Open Text's search engine that supports access to
SGML-encoded documents.  This Web-to-PAT Gateway utilizes the
Web's Common Gateway Interface (CGI) capability and SGML-to-HTML
filter programs.
     After briefly overviewing key technical concepts, the paper
explains the operation of the Web-to-PAT Gateway, using several
examples of how it is employed at the University of Virginia
Libraries, including access to text files such as a Middle
English collection, the Oxford English Dictionary, and the Text
Encoding Initiative's Guidelines for Electronic Text Encoding and

2.0  Key Concepts

This approach to using the Web to provide access to complex
textual resources involves many tools and concepts that may be
unfamiliar to the reader.  This section provides a very brief
overview of these complex topics and it describes their

+ Page 6 +

2.1  SGML and HTML

Standards and open systems must be an essential part of library
efforts to provide large-scale, wide-area access to textual
resources.  Textual resources must be reusable.  Because of the
cost of creating texts, it must be possible to use the texts in a
variety of settings with a variety of tools.  To that end, a
standards-based encoding scheme must be the foundation of text
     The Standard Generalized Markup Language (SGML), an
international standard, is such an encoding scheme, and it has
proven extremely valuable in effecting an open systems approach
with text. [1]  This paper is not the place to present a detailed
argument for using SGML, especially when this has been done so
effectively elsewhere. [2]  However, in addition to its value as
an internationally approved standard, SGML is ideally suited to
supporting text retrieval because it is a descriptive rather than
a procedural markup language.  SGML is a language designed to
reflect the structure or function of text, rather than simply its
layout or typography.  In a text retrieval system, portions of an
SGML document can be searched and retrieved, and functionally
different textual elements can be displayed in accordance with
their function.
     The difficulty of designing an implementation of SGML to
meet a broad range of text processing needs in the humanities has
been met by the Text Encoding Initiative (TEI) in its Guidelines
for Electronic Text Encoding and Interchange. [3]  The
application of SGML using the TEI Guidelines will play a central
role in ensuring that textual resources--particularly those
important to textual studies--are produced in a way that make
them flexible and of continuing value.  The TEI itself is a
collaborative project of the Association for Computers and the
Humanities, the Association for Computational Linguistics, and
the Association for Literary and Linguistic Computing.  Its
purpose is the promulgation of guidelines for the markup of
electronic text for a variety of disciplines involved in the
study of text.  In mid-1994, a comprehensive and detailed two
volume set of guidelines was published.  The print version of the
TEI Guidelines is an absolutely essential acquisition by
libraries; an electronic version has been made available by the
author. [4]

+ Page 7 +

     A central feature of SGML is the DTD (Document Type
Definition).  The DTD is a codification of the possible textual
characteristics in a given document or set of documents.  SGML
expresses the organization of a document without necessarily
using the file system paradigm (i.e., discrete files representing
the organizational components of a document).  It expresses
textual features (e.g., footnotes, tables, and headings) and the
building blocks of content (e.g., paragraphs) using a descriptive
language focusing on the role of the element, rather than some
presumed display value.  SGML is not a tag set, but a grammar,
with the "vocabulary"--or tags--of an individual document being
articulated in its DTD.  Using this rigorous grammar, SGML can
both declare information about the document in a way that can be
transported with the document and can enforce rules in the
application of markup by aiding in "parsing" the document.
     The HyperText Markup Language (HTML), which is used with the
Web, is a form of SGML expressed by its own unique DTD.  The
shape of the HTML DTD has changed significantly since first
articulated by researchers at CERN, and it continues to change
with the demands of the Web. [5]  HTML was designed to facilitate
making documents available on the Web, and it expresses a variety
of features such as textual characteristics and hypertext links.
These hypertext links are HTML's most useful capability because
they allow authors to link documents to other resources
throughout the Internet, effectively making the Internet into a
large hypertext document.

2.2  CGI and FORM Use

The Web is far more than a server protocol for the transfer of
HTML documents.  Among the many resources it offers in
facilitating sophisticated retrieval of information is the Common
Gateway Interface (CGI).  Like HTML, CGI is in transition.
However, in its current state, it offers capabilities that allow
the Web to support much more complex documents and retrievals
than HTML alone supports.  The Common Gateway Interface is a set
of specifications for external gateway programs to speak to the
Web's server protocol, HTTP.  It allows the administrator to run
external programs from the Web server in such a way that requests
from the server return a desired document to the user or, more
typically, generate a document on the fly.  This capability makes
it possible to provide uniform access to data structures or
servers that are completely independent of the HTTP, including
structures such as those represented in SGML documents or Z39.50
servers.  The CGI specification is available on the NCSA
documentation Web server. [6]

+ Page 8 +

     Closely associated with the CGI is the FORM specification,
which was first introduced with NCSA's Mosaic Web client.  This
feature is a client-independent mechanism to submit complex
queries, usually through a graphical user interface.
FORM-compliant interfaces such as Mosaic, Lynx (a UNIX VT100
client), and OmniWeb (a NeXTStep client) use fill-out forms,
check boxes, and lists to mediate queries between the user and
CGI resources.  Users respond by making selections that qualify
submissions to the server (e.g., checking a box to indicate that
a search is an author search) thereby making a complex
command-line syntax unnecessary. [7]

2.3  Computer Languages and CGI

CGI programs can be written in a variety of languages, including
UNIX shell scripts, C programs, and Perl.  In fact, there are few
limitations on the type of language that can be used.  Perl is
foremost among the options available to most Web administrators.
Largely the work of Larry Wall, Perl can be used to create
extremely fast and flexible programs with no practical limits on
the size of the material it can treat.  Perl also has outstanding
support for the UNIX "regular expression," making it ideal for
text systems where one form of markup must be translated to
another. [8]

3.0  The Web-to-PAT Gateway

The modular approach taken in the Web-to-PAT Gateway separates
the operations of retrieval to allow one component (e.g., an
SGML-to-HTML filter) to be upgraded without affecting other
components.  It should be emphasized that this separation of
operations grew out of local needs and that other approaches,
including an approach that combines all operations in a single
program, are possible.  The four steps are:

     1.   FORM Handling

          Users, with the aid of the FORM, submit a query.

     2.   CGI Query Handling

          The query is received and translated to a PAT search.

     3.   PAT Result Handling

          Information returned from PAT is transformed into lists
          or entries that can be selected.

+ Page 9 +

     4.   SGML-to-HTML Filtering

          The richer SGML is transformed into HTML.

This multi-stage approach has many advantages.  For example, it
is possible to use different programming languages or other
software tools for each processing stage, selecting them based on
their utility for particular functions or their ability to comply
with local requirements.  In the approach documented here, HTML
FORMs, shell programs, C programs, and Perl programs have been
used for the four operations.  Separating the functions also
allows persons with different responsibilities, skills, or
interests to manage the different processes.  For example, a
system administrator might manage the second and third stages,
while someone responsible for more aesthetic issues in the
delivery might manage parts of the first and the fourth stages.
At the University of Virginia Library, SGML-to-HTML filters
continue to be enhanced by staff from the Library's Electronic
Text Center in a process completely separate from the development
of other parts of the interface.

3.1  HTML FORM for Query Submission

The use of an HTML FORM to handle query submission may be simple
or complex.  The three examples given here demonstrate that
range: the Middle English FORM supports word and phrase searches;
the Oxford English Dictionary search provides a great deal of
information about the areas to be searched and information to be
retrieved; and the TEI Guidelines FORM allows users to browse the
document in a variety of ways, such as by chapter or other
section.  (The Middle English and TEI Guidelines resources are
encoded in SGML.)

+ Page 10 +

3.1.1  Middle English Query

The FORM created for Middle English materials was deliberately
made simple to allow users to retrieve keywords-in-context (KWIC)
without knowing commands such as those needed to view search
results. [9]
     A search term is requested from the user and registered as
the variable "query."  So that neither the user or system is
overwhelmed by large result sets, the size of result sets is
limited to 100 items, and an additional FORM option (registering
the variable "size") is included to help the user subsequently
move through the results 100 items at a time or to sample 100
items from the entire result set.

3.1.2  OED Query

The richness of the Oxford English Dictionary (OED) is often
overwhelming even for sophisticated users.  Most users do not
want keyword-in-context results and would prefer simple look up
capabilities.  The OED is a complex product designed to
facilitate a broad array of activities.  Consequently, even
simple searches require elaborate query structures.
     The OED FORM assists users in submitting many of the most
commonly performed searches, including dictionary entry retrieval
with simple look ups and truncated term look ups (e.g., "photo"
for all words beginning with this stem). [10]  It is also
possible to retrieve quotations by the quote's author (e.g.,
retrieval of all quotations authored by Chaucer).  This process
includes the following:

     1.   In the FORM, the user submits a search term which is
          captured as the variable "query."

     2.   The user selects the type of search.  Many types of
          searches are possible, including traditional look ups,
          alphabetic browses, full-text searches, and quotation

     3.   Several other elements are used to limit the size of
          results.  As in the Middle English search FORM, a
          default of no more than 100 results at a time may be
          viewed from each search.

+ Page 11 +

     4.   In addition, a variable called "period" is offered to
          allow users to limit quotation searches by century.

3.1.3  TEI Guidelines Query

The structured browsing of the TEI Guidelines adds another
important feature for mediating access to large or complex
collections.  Users of the TEI Guidelines are as likely to want
to read a chapter or section as they are to want to search the
     To facilitate this sort of browsing, an initial HTML page is
created containing the titles of the major SGML hierarchical
structures of the TEI Guidelines (e.g., the DIV0 element), and
each of these structures is linked to an HTML page containing the
titles of subsidiary structures (e.g., the DIV1 through DIV4
elements). [11]
     For example, the top-level HTML page is linked to the
secondary HTML page for Part I of the TEI Guidelines. [12]
     Figure 1 shows the top-level HTML page.

Figure 1.  Top-level HTML Page for the TEI Guidelines

TEI Guidelines for Electronic Text Encoding and Interchange (P3)

     You may also browse the Guidelines.
          * Bibliographic header of the TEI Guidelines
          * Preface
          * Acknowledgments
          * Changes from TEI P1 to TEI P3
          * Part 1: Introduction
          * Part 2: Core Tags and General Rules
          * Part 3: Base Tag Sets
          * Part 4: Additional Tag Sets
          * Part 5: Auxiliary Document Types
          * Part 6: Technical Topics
          * Part 7: Alphabetical Reference List of Tags and
          * Part 8: Reference Material


+ Page 12 +

Figure 2 presents the beginning of the HTML page for Part I of
the TEI Guidelines.

Figure 2.  Beginning of the HTML Page for Part I of the TEI

Part I: Introduction

     * 1: About these Guidelines
          + 1.1: Structure and Notational Conventions of this
               o 1.1.1: Structure
               o 1.1.2: Notational Conventions
          + 1.2: Underlying Principles and Intended Use
               o 1.2.1: Design Principles of the TEI Scheme
               o 1.2.2: Intended Use
                    # Use in Text Capture and Text
                    # Use for Interchange
                    # Use for Local Processing
          + 1.3: Historical Background
               o 1.3.1: Origin and Development of the TEI
               o 1.3.2: Future Developments

     * 2: A Gentle Introduction to SGML
          + 2.1: What's Special about SGML?
               o 2.1.1: Descriptive Markup


The URL for each list item in the Part I page contains the
information necessary to conduct a search and retrieve the
structural component being selected.  For example, to retrieve
the section "Structure and Notational Conventions of this
Document," the first subsection of the first chapter in Part I,
the URL points to the component extraction program tei-tocs, and
it specifies that this is an ID "struct" at level DIV2 (e.g,. the
section is bounded by the tags <DIV2 ID="struct"> and </DIV2>).

+ Page 13 +

3.2  CGI Query Negotiation

The CGI query handling operation accepts the search or action
initiated by the user and prepares it for submission to PAT. [13]
Information from the user is submitted to the CGI program as a
FORM or URL (e.g., <FORM ACTION=/bin/tei.sh>).  A wide range of
queries can be supported using this strategy.  For example, a
single word or phrase search can be submitted; it is also
possible to retrieve two words within a specified proximity to
each other, two structures (e.g., stanzas) that contain one or
more words or phrases, or structural units such as chapters.
UNIX Bourne shell scripts are used to interact with PAT.  The
program begins by testing to see if a query has been made, and
preliminary PAT results are tested to determine whether a valid
search was performed.

3.2.1  Middle English Query

In the Middle English query, simple searches are accepted and
KWIC results (64 characters in each) as well as a citation are
sent to the user's screen.  The "citation" is actually an ID
assigned to each text and extrapolated throughout the text, page
by page, by Electronic Text Center staff.  For example, the ID
"JefLett" is assigned to Jefferson's Letters, and, on page 234 of
the document, the ID will be "JefLett234."  This ID value becomes
a hypertext link for viewing the larger document context in the
subsequent processing of results.
     The PAT segment of the program for the Middle English
collection [14] consists of commands that:

     1.   Move PAT into its "QuietMode" for tagged communication
          with another program ({QuietMode raw}).  (See section
          3.3 for further discussion of QuietMode.

     2.   Set the sort order and direct PAT to use the ID
          described above as the identifier for each result
          ({PrintMode 3 ID page}).

     3.   Search the word or phrase.

     4.   Print the set of results requested by the user (e.g.,
          first hundred items).

+ Page 14 +

3.2.2  OED Query

In the OED query, a more sophisticated query that takes advantage
of PAT's structure recognition capabilities is submitted.  The
CGI script for the OED uses several structures based on tags in
the OED to search this text file and generate results using PAT.
The searches submitted by the OED FORM are created using shell
program case statements. [15]
     For example, if the user submitted a search asking for
quotations authored by Bailey in the sixteenth century, the
following query is submitted to PAT: docs C16 incl ("bailey"
within docs A).  This query retrieves document structures that
are 16th century quotes that contain "bailey" within the quote
author field.
     A search ends with the appropriate "print" command to PAT,
such as a command to print quote document structures (called Q

3.2.3  TEI Guidelines Query

The approach taken with the TEI Guidelines query represents the
richest implementation of this approach.  It combines searching
and browsing, and it enables browsing through the recognition of
document structure.  The CGI communication with PAT is also
surprisingly simple.  URLs are either static, embedded in the
menu options, or they are generated dynamically as the result of
a search (e.g., the TEI filter). [16]
     In the static URL strategy, the two elements needed to
conduct the PAT search (DIV level and ID value) are embedded in
each URL.  For example, the following URL sends the DIV level
(<DIV3>) and the ID value (ABTEI2) to the CGI script tei.sh:
http://etext.virginia.edu/bin/tei-tocs?div=DIV3&id=ABTEI2. [17]
Based on this information, the tei.sh script formulates the
following PAT query: docs DIV3 incl "<DIV3 ID=ABTEI2>."  The
script then issues the "print" command (pr.docs.DIV3) to retrieve
the relevant portion of the TEI Guidelines.

3.3  PAT Result Handling and QuietMode

Two stages of result handling, each relying on PAT's QuietMode,
take place before pages or dictionary entries are presented to
the user.  In QuietMode, PAT produces very helpful results with
all information tagged for more reliable processing.  For
example, the size of the result set is marked with <SSIZE> tags
(e.g., <SSIZE>23</SSIZE>), and every result can be made to begin
with a <HDR> tag (e.g., <HDR>AusEmma234</HDR>). [18]

+ Page 15 +

     The first stage produces only minor transformations,
primarily displaying the number of results retrieved and
separating each result into a separate line.  The results of the
first stage are piped to the second stage to produce a user
     The first-stage filters for the three example documents
perform the following actions:

     o    Middle English: the filter uses <SSIZE> tags to
          highlight the number of results. [19]

     o    OED: the filter ensures that each result is on a
          separate line, deferring issues such as using the
          <SSIZE> tags to highlight the number of results until a
          later stage. [20]

     o    TEI: the filter is essentially the same as that used
          for the Middle English collection. [21]

The second stage presents each element to the user in a sort of
index view so that a broader display can be produced.  The Perl
code for this stage usually produces a KWIC view, with each line
being a hypertext link to an expanded view of the result.  The
user sees the HDR element content as the link, but the byte
offset--the number of characters into the file that PAT uses to
locate results--is the actual search component of the link.
     The Perl code for the Middle English query is an example of
the code needed to produce a KWIC view.  It converts each result
to a view and associated hypertext links. [22]
     Results from the OED are presented to the user as a list of
dictionary headwords, from which the entire entry can be
displayed. [23]

3.4  Filtering SGML to HTML

The results of searches, each in a complex SGML form designed to
support the Web-to-PAT Gateway, are prepared by the final
processing stage for presentation to a Web client (e.g., Mosaic)
after being filtered to HTML.  Filtering, in these examples, is
again achieved by Perl.  Most SGML tags from the originating
files will be specialized and they will not have a corresponding
HTML tag.  For example, the quoted author element in the OED (the
<A> tag) has no corresponding HTML tag, but one might render it
as italicized text.  Because of this lack of correspondence and
the limited number of HTML tags, decisions are largely arbitrary
and draw on presentation or aesthetic needs.

+ Page 16 +

     The Perl program oed.pl is used to filter OED tags to HTML.
[24]  This filter and the resulting output demonstrates the
challenge of filtering rich, heterogeneous text to HTML.  A
sample tagged OED entry is included in Appendix C to illustrate
the problems encountered.  Despite many compromises in mapping
complex tags to simple presentation characteristics, information
can be presented attractively to a user with a GUI client.
Future improvements in HTML and the ability of clients to
interpret a variety of tags should enhance the display of OED
     Subsequent to the KWIC view for TEI and Middle English
queries, more thorough transformations are performed on the
texts.  For example, upon being selected, a result's byte offset
is sent to a program that uses PAT to print a 1,500 character
context for a result.  This character context may contain any of
the possible tags in the DTD, so a filter that represents all
possible element values is created.  At this time, the filters
fall short in many areas, in particular in their ability to
express complex relationships made possible in the DTD.  For
example, an element may have an attribute value suggesting that
it should be tagged one way (e.g., "gloss" for glossary), as well
as having sub-elements of the same type with different attribute
values (e.g., "bullets").  For example, one might encounter the
partial character context shown in Figure 3.

Figure 3.  Example of Complex Element Attributes

<LIST TYPE="gloss">
          <LABEL>name of item 1
          <ITEM>contents of item 1
          <LABEL>name of item 2
          <LIST TYPE="bullets">
               <ITEM>contents 1 of item 2
               <ITEM>contents 2 of item 2
               <ITEM>contents 3 of item 2


At the present time, the simple stream-oriented filters cannot
differentiate between tags with the same name (e.g., the <LIST>
tags) in this type of complex nesting relationship.  Two example
filters have been made available by the author. [25]

+ Page 17 +

4.0  Preparing Texts with PAT

Little or no preparation of SGML texts is necessary to be able to
implement the Web-to-PAT Gateway.  In order to provide a useful
indicator of location for KWIC views, we typically add an ID
element with concise positional information.  For example, in our
Modern English Texts, we add a combination of author, title, and
pagination to create an ID such as JefLett244, which represents
Thomas Jefferson, Letters, page 244.  These ID values are limited
to ten characters.
     Since the TEI Guidelines use "minimization" (i.e., omit many
end tags where they are implied by context), preparation of the
TEI Guidelines was more complex, and it included the following

     o    Normalization

          A parser was used to normalize the text.  This resulted
          in all elements being closed and being put in
          uppercase.  For example, if a chapter begins with the
          <div1 id=AB> tag and has no end tag, the initial tag is
          changed to <DIV1 ID="AB"> and the chapter is closed
          with a </DIV1> end tag.

     o    Added <ID> Values

          Three DIV1 elements did not have ID attributes.  These
          were added to aid in retrieval.  Attributes such as
          ID="bibliog" for the bibliography were also included.

     o    ID Element

          An ID was created for each DIV1, with the value of the
          ID attribute being copied to the ID.  For example, for
          the chapter called "A Gentle Introduction to SGML," the
          <DIV1 ID="SG"> now has <ID>SG</ID>.  This makes it
          possible to display the ID value for each DIV1 in the
          KWIC views.

+ Page 18 +

5.0  Testing

The Web-to-PAT Gateway has been employed to access text
collections at a number of institutions, including the University
of Chicago, the University of Michigan, and the University of
Virginia.  Open Text has generously allowed the University of
Michigan and the University of Virginia to provide other sites
with access to selected PAT-based collections or resources.  To
examine example components of the Web-to-PAT Gateway, use the
test page at the following URL: http://www.lib.umich.edu/hti/.

6.0  Conclusion

The Web-to-PAT Gateway is an effective method for accessing text
collections, and it suggests important possibilities for
accessing other types of resources. [26]
     The University of Virginia provides access to many
collections of resources using clients designed to support
complex analysis, where users can create sets, combine them, and
use a range of operations facilitated through a wide array of
menus.  These clients are frequently much more complicated than
is desirable for simple operations, such as word look ups in the
OED.  The Web-to-PAT Gateway allows users to do simple word look
ups in the OED or to formulate simple queries in the text
collections without needing to understand PAT syntax or the
organization of the collections.
     The Web-to-PAT Gateway strategy could also be applied to
other types of texts, such as SGML-encoded journals.  For
example, a journal run marked up according to the more elaborate
AAP (Association of American Publishers) DTD (ISO 12083) could
return articles to the user using simple PAT queries.  Another
approach might set up CGI scripts to facilitate browsing where a
user selects a browse by author/title option and is given a
series of choices that use PAT queries to produce a menu of
either journal titles, volume/issue numbers, or author/title
options.  The Web can be an effective means of accessing the
original files in a fuller SGML markup without altering the
markup or resorting to fragmenting the material into thousands of
files corresponding to the individual articles or even parts of
articles.  Similar strategies for books and documentation can be
imagined as well.
     The Web-to-PAT Gateway offers significant evidence that SGML
can serve as a delivery format for electronic materials sold by
publishers to libraries and that SGML can serve as an effective
internal file format on a library server.

+ Page 19 +


1.  Information Processing--Text and Office Systems--Standard
Generalized Markup Language (SGML) (Geneva: The International
Organization for Standardization, 1986).

2.  Perhaps the best argument to date for the use of SGML in
literary and linguistic computing is the often reprinted article:
James H. Coombs, Allen H. Renear, and Stephen J. DeRose, "Markup
Systems and the Future of Scholarly Text Processing," in The
Digital Word: Text-based Computing in the Humanities, eds. George
P. Landow and Paul Delany (Cambridge, MA: MIT Press, 1993), 85-
118.  Also very valuable is the thorough guide to the standard
itself: Charles F. Goldfarb, The SGML Handbook (New York: Oxford
University Press, 1990).

3.  The first preliminary draft of the TEI Guidelines was
published in 1990.  The second draft (known as P2) was
subsequently published in fascicles.  It is available at the
following URL: ftp://ftp.ex.ac.uk/pub/SGML/tei/p2.  A complete,
revised edition (P3) was published in 1994: C. M. Sperberg-
McQueen and Lou Burnard, eds., Guidelines for Electronic Text
Encoding and Interchange (Chicago: Text Encoding Initiative,

4.  URL: http://words.hh.lib.umich.edu/TEI/.

5.  The specifications for HTML continue to be in draft form, but
they are being discussed by the Internet Engineering Task Force.
A current version of the draft specification can be found at the
following URL: file://info.cern.ch/pub/docs/html-spec.ps.Z.

6.  Current CGI specifications and very useful examples can be
found at the following URL: http://hoohoo.ncsa.uiuc.edu/

7.  FORM options and implementation examples are documented by
NCSA at the following URL: http://www.ncsa.uiuc.edu/SDG/

8.  Larry Wall and Randal L. Schwartz, Programming Perl
(Sebastopol, CA: O'Reilly & Associates, 1991).

+ Page 20 +

9.  The form can be seen at the following URL: http://
words.hh.lib.umich.edu/ME.html.  Other searches are facilitated
as well, including proximity searches and traditional Boolean
searches.  In contrast to the simple search discussed in this
article, these searches mediate user communication by taking
multiple inputs (e.g., "love" and "envy"), an operator (e.g.,
near or intersect), and, in the case of the Boolean search, a
document structure to use for intersection (e.g., a poem or
chapter).  This allows support for queries such as love near envy
or stanzas that include love intersected with stanzas that
include envy.

10.  URL: http://words.hh.lib.umich.edu/oed.html.

11.  The menus were created using a combination of manual and
automated processes; the latter using PAT to identify components
and programs (e.g., Perl programs) to convert output to HTML and
URLs.  This approach was selected in order to provide a static
view of the organization of the TEI Guidelines.  It should be
stressed, however, that a completely automated approach is
possible and may be incorporated in subsequent projects.  In a
more automated approach, something like the following would be

     1.   User selects a TEI page, which initiates a PAT search
          returning all DIV0 elements HEAD.  (For example, one
          might request docs HEAD within docs DIV0 if the HEAD
          element were unique.)

     2.   The information from the first step enables the dynamic
          construction of a menu option containing a URL that
          would extract HEAD items at levels DIV1 through DIV4.

     3.   The information about lower levels within each part
          could then be used to create URLs such as those
          described earlier (e.g., http://etext.virginia.edu/

12.  URLs: http://words.hh.lib.umich.edu/TEI/ and http://

+ Page 21 +

13.  It should be emphasized that in this and many other stages,
extensive interaction with the file system takes place, and every
precaution should be taken to ensure security and protect against
unpredictable results.  Even though CGI/httpd implementors have
taken precautions against dangerous queries, the httpd server
should be run as "nobody" (or a comparable user) to protect
against malicious queries.  Also, note the precautions taken
against communication errors with PAT and the prevention of
runaway processes.

14.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

15.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

16.  See tei.pl available at the following URL: ftp://

17.  URL: ftp://ftp.lib.virginia.edu/www/staffpubs/tei.sh.

18.  In most cases, a step is introduced to remove all newlines,
conducted by piping output to the "tr" command (e.g., | tr -d
"\012").  This is done to aid Perl in treating tag content that
crosses boundaries.  For example, the OED filter creates output
where the results are rendered as a series of single lines, one
for each result.  It is not possible to remove the newline
characters in the TEI Guidelines because many of the examples
rely on formatting with newlines in CDATA elements.  This results
in inadequacies in the filtering where, for example, the
beginning and tags are separated by several lines and the
corresponding HTML are best determined by an attribute value
(e.g., TYPE="gloss").  However, this is a shortcoming in the
author's Perl skills rather than a fault in the TEI markup.

19.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

20.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

21.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

+ Page 22 +

22.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

23.  This Perl code is available at the following URL: ftp://

24.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

25.  URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/
www-to-pat/ota.pl.  See also a filter for the TEI P3 DTD at the
following URL: ftp://sansfoy.hh.lib.umich.edu/htdocs/

26.  There is still a compelling need for more specialized tools
to access the same collections.  Persons involved in complex
analytical activities need to be able to combine sets in a
variety of ways, to see numbers associated with previous searches
at a glance, and to create and access structures not otherwise
accessible through the Web-to-PAT Gateway.  Currently the
University of Virginia supports a locally developed VT100 client
as well as commercial X Window System and Microsoft Windows
clients from Open Text.

Appendix A.  Proposed Enhancements

The following enhancements are proposed for the Web-to-PAT

     1.   Incorporate PAT API

          Incorporating the Open Text Application Programming
          Interface (API) tools will make it possible to access
          PAT directly from the CGI programs, rather than
          creating a separate search file.  This will be more
          efficient, will make possible testing for search size
          without re-executing the search, and may make possible
          a degree of interaction with the text not currently

+ Page 23 +

     2.   Use Perl and Subroutines

          Perl is probably the most efficient programming
          language to mediate interaction between a FORM and PAT,
          and it can execute the separate components of the Web-
          to-PAT Gateway outlined in this paper as subroutines.

     3.   Improve SGML Filters

          If filters can be written to recognize the full range
          of relationships made possible by the SGML, filtering
          could be more attractive.  For example, nested LIST
          could be differentiated both by the nesting and by the
          attribute values.  Until a filter can be written to
          exploit these characteristics, it will fall short of
          what is possible.

Appendix B.  OED Implementation Cookbook

This Appendix assumes the reader is familiar with the
installation and configuration of the Web server (i.e., httpd).
It is also extremely useful to have a familiarity with PAT and
the OED.

     1.   Install the Web server (i.e., httpd).  This
          implementation has only been tested with the NCSA
          httpd, available at the following URL: ftp://

     2.   The locations of CGI scripts and the PAT executables
          are registered in the httpd's srm.conf file.  For
          example, if we were put the CGI scripts and executables
          in the directory /patbin, the entry might read:

               ScriptAlias /patbin/

     3.   Access to the OED must be restricted to persons at your
          institution.  For the NCSA httpd, this can be done by
          creating a file called .htaccess in the /patbin
          directory and declaring an acceptable set of IP
          addresses.  See the httpd documentation for further
          information.  Note that it is not important to restrict
          access to the HTML FORM oed.html, but it is to restrict
          access to the executable files.

+ Page 24 +

     4.   A data dictionary, probably called 2e.dd, will have
          been included with your copy of the OED.  Copy this
          data dictionary (e.g., copy 2e.dd to 2eWWW.dd) and in
          the new dictionary change the names of the "Regions" so
          that the simpler tag names are used.  For example,
          change the name Entry to E.

     5.   Put the following files in the /patbin directory:

          o    oed-kwic

          o    oedkwic-filt

          o    oed-parse.pl

          o    kwic.input.sed

          o    oed.pl

          o    oed2html.pl

          o    oed-id

          o    oed.sh

     6.   Make certain that all the files in the /oedbin
          directory are executable.

     7.   Change the relevant portions (paths and variables such
          as titles) in the first lines of oed-kwic, oed-id, and

     8.   Alter oed.html to point to the correct path (e.g.,
          /patbin), and alter oed.pl and oedkwic-filt to change
          /oedbin to the correct path (e.g., /patbin).

     9.   Check the location of Perl in your system and change
          all of the Perl scripts to conform to this location.

+ Page 25 +

Appendix C.  Sample Tagged OED Entry

revv.g</IPH></IPR>, <PS>v.</PS></HG><ET>f. <XR><XL>de-</XL>
<SN>II</SN>. <SN>2</SN></XR> +<XR><XL>bug</XL><PS>sb.</PS>
<HO>2</HO></XR></ET><p><S4><#>1</#><S6><DEF><PS>trans.</PS>  =
<A>J. Stroud</A><W>Shorn Lamb</W> vi. 70 <T>We'll..take them
round to the Clinic, and..get them debugged there.</T></Q></Q>
</S6></S4><p><S4><#>2</#><S6><DEF><LB>slang.</LB>To remove
faults from (a machine, system,etc.).</p></DEF><QP><EQ><Q>
<D>1945</D> <W>Jrnl. R. Aeronaut. Soc.</W> XLIX.  183/2

<T>It ranged from the pre-design development of essential
components, through the stage of type test and flight test
and `debugging' right through to later development of the
engine.</T></Q></EQ><Q><D>1959</D><W>New Scientist</W> 26

Mar. 674/1 <T>The `debugging' time spent in perfecting a
non-automatic programme.</T></Q><Q><D>1964</D> <W>Discovery</W>
Oct. 51/3 <T>This failure report plays a vital role in the
process by which the scientist corrects or de-bugs his
programme.</T></Q><Q><D>1964</D> <A>T.  W. McRae</A>
<W>Impact of Computers on Accounting</W> iv. 99 <T>Once we have
`debugged' our information system.  </T></Q><Q><D>1970</D>
<A>A. Cameron</A> et al. <W>Computers &amp. O.E.

Concordances</W> 49 <T>Program translation, debugging, and
trial runs of the concordance were performed at the University
of Michigan Computer Center.</T></Q><Q><D>1970</D> <A>A.

+ Page 26 +

Cameron</A> et al. <W>Computers &amp. O.E.  Concordances</W>,
49 <T>By Christmas the program was debugged.</T></Q></QP></S6>
</S4><p><S4><#>3</#> <S6><DEF>To remove a concealed microphone
or microphones from (a room, etc.); to free of such listening
devices by electronically rendering them inoperative.  Cf.
orig.<LB>U.S.</LB></p></DEF><QP><Q><D>1964</D> <W>Business
Week</W> 31 Oct. 154 (<W>heading</W>) <T>When walls have ears,
call a debugging man.</T></Q><Q><D>1964</D><W>Business Week</W>
31 Oct. 154 (<W>heading</W> 158/2 )<T>He quotes high fees for
his work, saying that debugging equipment is expensive.</T></Q>
<Q><D>1966</D> in Random House Dict. </Q><Q><D>1969</D><W>New
Scientist</W> 16 Jan. 128/3<T>`Debugging' the boardroom and the
boss's telephone may become as common in industry as in the
unreal world of the super-spy. </T></Q><Q><D>1976</D><A>M.
Machlin</A> <W>Pipeline</W> xxxi. 353 <T>The room..had steel
walls and had been rigorously de-bugged.</T></Q><Q><D>1978</D>
<W>Sunday Mail Mag.</W> (Brisbane) 9 Apr. 3/6 <T>Jamil,
America's leading `debugging' expert, discovered the secret
of an exported `bug' which should not have worked.</T></Q>
<Q><D>1987</D><W>Daily Tel.</W> 3 Apr. 1/8 <T>American
officials are scrambling to `de-bug' their embassy in Moscow
before the arrival of Mr Shultz, Secretary of State, on Monday
week.</T></Q></QP></S6></S4><p><S4><SE>Also <BL>
<DEF><PS>vbl. sb.</PS> (see senses 2, 3 above).</DEF>


The author would like to express his deep gratitude to others who
have assisted in the process of making the Web-to-PAT Gateway
possible.  In particular, I am especially indebted to Mark Olsen
of the ARTFL project, who contributed his OED filter and provided
guidance in establishing communication between the Web and PAT,
and to Hannah Kaufmann of Princeton University and Peggy Yetter
of the University of Pennsylvania for their persistence in
working through early versions of the Gateway.
     Thanks also to Charles Bailey for his unflagging editorial
assistance with this paper.

+ Page 27 +

About the Author

John Price-Wilkin, Coordinator of the Humanities Text Initiative
of the University of Michigan Library, the School of Library and
Information Studies, and the University of Michigan Press, 309
North Hatcher Graduate Library, University of Michigan, Ann
Arbor, MI 48109-1205.  Phone: (313) 764-8074.  Internet:

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