2964 lines
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2964 lines
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The Public-Access Computer Systems Review
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Volume 5, Number 5 (1994) ISSN 1048-6542
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To retrieve an article file as an e-mail message, send the GET
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command given after the article information to
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listserv@uhupvm1.uh.edu. (Files are also available from the
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University of Houston Libraries' Gopher server: info.lib.uh.edu,
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port 70.)
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CONTENTS
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COMMUNICATIONS
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The HyperText Markup Language (HTML) and the World-Wide Web:
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Raising ASCII Text to a New Level of Usability
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By Jeff Barry (pp. 5-62)
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To retrieve this file: GET BARRY PRV5N5 F=MAIL
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Since the release of the first NCSA Mosaic clients in 1993, the
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World-Wide Web (also known as the Web) has become an increasingly
|
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popular tool for disseminating information over the Internet.
|
|
The HyperText Markup Language (HTML) is used to structure and
|
|
format documents for presentation on the Web. HTML enhances
|
|
ASCII files with markup tags that permit the display of a variety
|
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of fonts, images, and highlighting options; designate structural
|
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elements such as headers, lists, and paragraphs; and provide
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hypertext links to other documents on the Internet. This
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tutorial describes HTML tags, provides examples of their use,
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offers guidelines for organizing hypertext documents, suggests
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what types of documents are suitable for the Web, and explores
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the future of HTML.
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COLUMNS
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Public-Access Provocations: An Informal Column
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And Only Half of What You See, Part II: Skeletons in the
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Catalog
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By Walt Crawford (pp. 63-66)
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To retrieve this file: GET CRAWFORD PRV5N5 F=MAIL
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The Public-Access Computer Systems Review
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Editor-in-Chief
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Charles W. Bailey, Jr.
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University Libraries
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University of Houston
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Houston, TX 77204-2091
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(713) 743-9804
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Internet: lib3@uhupvm1.uh.edu
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Associate Editors
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Columns: Leslie Pearse, OCLC
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Communications: Dana Rooks, University of Houston
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Editorial Board
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Ralph Alberico, University of Texas, Austin
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George H. Brett II, Clearinghouse for Networked Information
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Discovery and Retrieval
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Priscilla Caplan, University of Chicago
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Steve Cisler, Apple Computer, Inc.
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Walt Crawford, Research Libraries Group
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Lorcan Dempsey, University of Bath
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Pat Ensor, University of Houston
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Nancy Evans, Pennsylvania State University, Ogontz
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Charles Hildreth, READ, Ltd.
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Ronald Larsen, University of Maryland
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Clifford Lynch, Division of Library Automation,
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University of California
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David R. McDonald, Tufts University
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R. Bruce Miller, University of California, San Diego
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Paul Evan Peters, Coalition for Networked Information
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Mike Ridley, University of Waterloo
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Peggy Seiden, Skidmore College
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Peter Stone, University of Sussex
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John E. Ulmschneider, North Carolina State University
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Technical Support
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Tahereh Jafari, University of Houston
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Publication Information
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Published on an irregular basis by the University Libraries,
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University of Houston. Technical support is provided by the
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Information Technology Division, University of Houston.
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Circulation: 8,229 subscribers in 64 countries (PACS-L) and 2,652
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subscribers in 51 countries (PACS-P).
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Back issues are available from listserv@uhupvm1.uh.edu. To
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retrieve a cumulative index to the journal, send the following e-
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mail message to the list server: GET INDEX PR F=MAIL.
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Back issues are also available from the University of Houston
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Libraries' Gopher server. Point your Gopher client at
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info.lib.uh.edu, port 70, and follow this menu path:
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Looking for Articles
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Electronic Journals
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University of Houston Libraries E-Journals
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The Public-Access Computer Systems Review
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The journal's URL is gopher://info.lib.uh.edu:70/11/articles/e-
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journals/uhlibrary/pacsreview.
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The first three volumes of The Public-Access Computer Systems
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Review are also available in book form from the American Library
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Association's Library and Information Technology Association
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(LITA). The price of each volume is $17 for LITA members and $20
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for non-LITA members. All three volumes can be ordered as a set
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for $45 (indicate that you want the PACS Review set, order number
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7712-X). To order, contact: ALA Publishing Services, Order
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Department, 50 East Huron Street, Chicago, IL 60611-2729, (800)
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545-2433.
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The Public-Access Computer Systems Review is an electronic
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journal that is distributed on the Internet and on other computer
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networks. There is no subscription fee.
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To subscribe, send an e-mail message to
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listserv@uhupvm1.uh.edu that says: SUBSCRIBE PACS-P First Name
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Last Name.
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The Public-Access Computer Systems Review is Copyright (C)
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1994 by the University Libraries, University of Houston. All
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Rights Reserved.
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Copying is permitted for noncommercial use by academic
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computer centers, computer conferences, individual scholars, and
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libraries. Libraries are authorized to add the journal to their
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collection, in electronic or printed form, at no charge. This
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message must appear on all copied material. All commercial use
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requires permission.
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-----------------------------------------------------------------
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+ Page 5 +
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Barry, Jeff. "The HyperText Markup Language (HTML) and the
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World-Wide Web: Raising ASCII Text to a New Level of Usability."
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The Public-Access Computer Systems Review 5, no. 5 (1994): 5-62.
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To retrieve this file, send the following e-mail message to
|
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listserv@uhupvm1.uh.edu: GET BARRY PRV5N5 F=MAIL. (The file is
|
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also available from the University of Houston Libraries' Gopher
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server: info.lib.uh.edu, port 70.)
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-----------------------------------------------------------------
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1.0 Introduction
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Since the release of the first NCSA Mosaic clients in 1993, the
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World-Wide Web (also known as the Web) has become an increasingly
|
|
popular tool for disseminating information over the Internet.
|
|
The HyperText Markup Language (HTML) is used to structure and
|
|
format documents for presentation on the Web. HTML enhances
|
|
ASCII files with markup tags that permit the display of a variety
|
|
of fonts, images, and highlighting options; designate structural
|
|
elements such as headers, lists, and paragraphs; and provide
|
|
hypertext links to other documents on the Internet. This
|
|
tutorial describes HTML tags, provides examples of their use,
|
|
offers guidelines for organizing hypertext documents, suggests
|
|
what types of documents are suitable for the Web, and explores
|
|
the future of HTML.
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2.0 Background of the Web
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The World-Wide Web initiative originated with the European
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Laboratory for Particle Physics (CERN) in 1989 as an attempt to
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electronically distribute the literature of high-energy physics
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to researchers. [1] The World-Wide Web initiative was based on
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the hypertext concept. By creating computer linkages from the
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citations of an article to the corresponding source documents,
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users would be able to navigate through a body of related
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literature online simply by following the "electronic footnotes."
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In order to realize such a system, computer protocols and
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standards had to be created for describing the structure of
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documents, specification of links, and the transmission of
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documents over a computer network.
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As the World-Wide Web developed, key supporting technologies were
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established. The HyperText Markup Language (HTML) describes the
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organization of a document so that certain structural elements
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can be uniquely identified and accessed over the Internet.
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Within an HTML document, links to other information on the
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Internet are specified through the use of Uniform Resource
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Locators (URLs). The actual process of transferring HTML
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documents over the network in the Web is accomplished by
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computers employing the HyperText Transfer Protocol (HTTP); the
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computers that deliver HTML documents to users of the Net are
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usually referred to as "Web servers." Individuals access
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documents on Web servers through client software on their local
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machines, such as Mosaic, Cello, and Lynx. Since the hypertext
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nature of the Web facilitates the browsing of networked
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resources, Web client software has generically come to be known
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as "browsers." Although it is important to the operation of the
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Web, authors of HTML documents don't need understand the details
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of the HTTP protocol.
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The Web has evolved beyond being just a hypertext tool: it
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is now a hypermedia environment that incorporates images, sound,
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and even video. In fact, the diversity of documents found in the
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World-Wide Web has fostered the need for ongoing revisions of
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HTML. This process is largely supported by ad hoc volunteer
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efforts by many individuals around the world who are dedicated to
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seeing the Web evolve into a more mature and stable networked
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communications tool. As individuals have tried to apply the HTML
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tags to a variety of document types, the limitations of HTML have
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become very clear. An excellent overview of these limitations
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can be found in a recent paper by John Price-Wilkin. [2]
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Nevertheless, the Web is a precursor of the networked environment
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that will permeate libraries in the future. As HTML tags are
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explained in this tutorial, areas that might change with the next
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HTML specification are identified.
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3.0 Structure of HTML Documents
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An HTML document is simply an ASCII text file that has been
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marked up with standardized tags in order to provide structure to
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the text (see Section 11 for a discussion of HTML's relationship
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to SGML). One of the disadvantages of plain ASCII files is that
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they do not provide the reader with information about document
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structure or formatting. Whenever you convert a file created in
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a word processor to ASCII, the fonts, bullets, bold, italics, and
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other formatting information are lost during the conversion.
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Although it utilizes ASCII files, HTML provides information
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about a document's structure (e.g., title, headings, and
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paragraphs) and format (e.g., bold and italics) through the use
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of standardized markup tags.
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In HTML terminology, a document is composed of "elements."
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In simple terms, an element can be viewed as being either a part
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of a document, such as a title; a formatting code, such as bold;
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a hypertext link; or an image. In turn, elements are identified
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by markup tags. In general, this paper will simplify HTML
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terminology and use "tag" to refer to both elements and actual
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markup tags. For the details of HTML's complex document
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structure, consult the HyperText Markup Language (HTML), Version
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2.0 specification. [3]
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For example, the tag to begin a title is <TITLE>, the tag to
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begin a first-level heading is <H1>, and the tag to begin a
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paragraph is <P>. The beginning tag is followed by the text of
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the title, heading, or paragraph respectively. Most HTML tags
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are used in pairs, although some tags can be used singularly.
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The beginning tag is usually called the "start tag." The ending
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tag is usually called the "end tag." Except for the addition of
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a forward slash, the end tag is the same as the start tag. For
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example, the tag to end a title is </TITLE>, the tag to end a
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first-level heading is </H1>, and the tag to end a paragraph is
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</P>.
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Figure 1 presents an example of an HTML document.
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-----------------------------------------------------------------
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Figure 1. Example HTML Document
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-----------------------------------------------------------------
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<TITLE>The Title of Your Document is Entered Here</TITLE>
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<H1>The Heading of Your Document is Entered Here</H1>
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<P>The text of the first paragraph of your document is entered
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here.</P>
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-----------------------------------------------------------------
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+ Page 8 +
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All HTML tags have the same general format shown in Figure 2.
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-----------------------------------------------------------------
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Figure 2. General HTML Tag Format
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-----------------------------------------------------------------
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<TAG>text</TAG>
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Start Tag | |
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Content |
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End Tag
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-----------------------------------------------------------------
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Tags are not case sensitive. For example, <title> is equivalent
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to <TITLE>. (For the convenience of the reader of this paper,
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tag names, actual tags, and tag attributes are shown in
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uppercase.)
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HTML documents can be created using either:
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1. Regular text editors in which the author enters the
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markup tags by hand or by means of a macro.
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2. Specialized HTML editors that automatically insert the
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appropriate markup tags at locations designated by the
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author.
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3. Conversion programs that take a word processing file
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and translate it into HTML.
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Since HTML document editors and conversion programs are still
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being developed, the most common method of creating HTML
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documents has been to use a text editor and to manually insert
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markup tags. Since a relatively small number of tags are used in
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HTML, this method is not as tedious as it sounds. Regardless of
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the means used to create the document, a solid understanding of
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HTML tags is essential for authors preparing documents for the
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Web. The simplicity of HTML and the ability to generate such
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documents without specialized tools facilitates the ease of entry
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into the world of networked hypermedia.
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In this tutorial, an example of creating a "home page" in
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HTML will be provided. A home page commonly refers to the first
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document a user sees when starting a Web browser. Many users
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create their own home pages for organizing information about
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their favorite Internet sites. By following the examples in this
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tutorial, you should be able to create your own home page.
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+ Page 9 +
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4.0 Structural Elements
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An HTML document consists of at least three essential elements: a
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title, a heading, and the text that forms the body of the
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document. The body of the document can be in the form of
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paragraphs, lists, images, or a combination of elements. Figure
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3 presents an example home page.
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-----------------------------------------------------------------
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Figure 3. Example Home Page
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-----------------------------------------------------------------
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<TITLE>Jeff's Home Page</TITLE>
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<H1>Jeff's Home on the Net</H1>
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<P>Your "home page" may include links to other information
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sources on the network, information about yourself, and even
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your photograph. HTML provides the flexibility of crafting a
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toolbox of networked resources that meets your needs.</P>
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-----------------------------------------------------------------
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4.1 TITLE Tag (<TITLE>)
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The TITLE tag (<TITLE>) describes the content of the document.
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Rather than displaying the text of the TITLE tag as part of the
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document, Web browsers usually display it in an area above the
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document window; different types of browsers may display the
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title differently.
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The TITLE tag should both describe the content of a document
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and provide the reader with an indication of the context of the
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document. If the HTML document is part of a multi-document work,
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then the parent document might also be part of the TITLE tag.
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For example, the following title would be meaningless on its
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own: <TITLE>Introduction</TITLE>. A better title would include
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the context of the document, such as: <TITLE>Dead Sea Scrolls
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Exhibit--Introduction</TITLE>.
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Providing meaningful titles to hypertext documents
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facilitates the web-like linkage of congruent resources. In
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HTML, the TITLE tag serves not only as a concise description of a
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document, but it also helps users to navigate among a set of
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documents that, in actuality, might exist on a number of
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different Web servers throughout the world.
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While no limit is placed on the length of this tag, titles
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should be kept brief. Since documents may be displayed or
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utilized by many different types of client software, there is no
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guarantee that lengthy titles will not be truncated, possibly
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resulting in the loss of information. A "rule of thumb" is to
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keep document titles to less than 64 characters.
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+ Page 10 +
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4.2 HEADING Tags (<H1> to <H6>)
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HTML provides for six different levels of HEADING tags: <H1>,
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<H2>, <H3>, <H4>, <H5>, and <H6>. The most prominent heading is
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assigned the <H1> tag. A subsection would be marked with the
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<H2> tag. A section within the subsection would be designated
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with the <H3> tag.
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The Web browser supplies the appropriate sized font for each
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heading level. The font used for an <H1> heading is more
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prominent than the font for an <H2> heading, whereas the font
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used for an <H2> heading is more prominent than the font used for
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an <H3> heading.
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Heading numbers should not be mixed. For example,
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<H1>Jeff's Home on the Net</H2> would not be a valid heading
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because the number of the end tag is not the same as the number
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for the start tag.
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Since headings, unlike titles, are displayed by browsers
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with the text of the HTML document itself, the <H1> heading is
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the most visually prominent text displayed.
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The use of a HEADING tag implies a paragraph break before
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and after the tag. When a heading is displayed in a Web browser,
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adequate white space will be added around the text of the heading
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in order to form the paragraph break.
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Try to choose the appropriate level heading based upon the
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section's place within the document and not based upon the
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appearance of the heading when displayed in a browser.
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4.3 PARAGRAPH Tag (<P>)
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A mild controversy exists among HTML authors about the PARAGRAPH
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tag (<P>). Early HTML specifications used the PARAGRAPH tag to
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indicate a paragraph break. However, using the tag in this
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manner only provided formatting information to browsers (i.e.,
|
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when to add blank space around text). Many HTML users viewed the
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PARAGRAPH tag as a start tag "containing" a block of text that
|
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functioned as a paragraph, just as a HEADING tag contained text
|
|
that functioned as a header.
|
|
The latest revision of the HTML specification indicates that
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|
the PARAGRAPH tag represents a paragraph and not a paragraph
|
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break. The value of viewing the PARAGRAPH tag as a container,
|
|
rather than a separator, is that a containing tag conveys
|
|
structural information, whereas a separating tag simply implies
|
|
formatting. Think of the PARAGRAPH tag as containing a block of
|
|
text that functions as a paragraph and not as a tag that only
|
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separates one text block from another.
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+ Page 11 +
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To keep documents in conformance with current HTML practice,
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it is best to place the <P> tag at the beginning of each
|
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paragraph.
|
|
Note that the end tag (</P>) is optional and is usually left
|
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out.
|
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The use of the PARAGRAPH tag to force the addition of white
|
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space around text that is not a paragraph is strongly
|
|
discouraged.
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5.0 Presentation Tags
|
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One of the primary hurdles that authors face in preparing HTML
|
|
documents is moving from a presentation perspective to a
|
|
structural one. Word processors focus the author's energies on
|
|
the presentation of a document. When preparing documents in a
|
|
word processor, the author considers fonts and other presentation
|
|
characteristics such as bold, underlining, italics, and bullets.
|
|
HTML was initially designed to allow the author to focus on
|
|
a document's content rather than its presentation. The software
|
|
that displays HTML documents is responsible for rendering the
|
|
document for the appropriate display device. The intention of
|
|
HTML, as with other structural markup languages, is to relieve
|
|
the author from presentation considerations. HTML documents
|
|
should be platform independent: the same HTML document should
|
|
look just as good with NCSA Mosaic for the Macintosh as with NCSA
|
|
Mosaic for Microsoft Windows.
|
|
One of the problems that many people have in learning HTML
|
|
is that all Web browsers do not support the same conventions.
|
|
For example, early versions of NCSA Mosaic for Microsoft Windows
|
|
only supported a limited set of tags. When creating HTML
|
|
documents, the author must trade off the present inconvenience
|
|
that, if all HTML tags are used, some browsers may only display a
|
|
subset of them against the future inconvenience that HTML markup
|
|
that is restricted to accommodate current Web browser limitations
|
|
will need to be upgraded as these browsers become more
|
|
sophisticated.
|
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|
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+ Page 12 +
|
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|
|
HTML presentation elements are divided into two sets:
|
|
logical style and physical style. Logical tags describe the role
|
|
that the text plays in a document, such as a citation, a
|
|
definition, or an emphasized statement. Physical tags simply
|
|
indicate the desired appearance of text, such as bold or italics.
|
|
While it is natural in a word processor to indicate when text
|
|
should be in bold or italics, the author of an HTML document
|
|
should use logical rather than physical elements whenever
|
|
possible. As Coombs et al. note:
|
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|
|
Using descriptive markup to identify the logical elements of
|
|
a document not only simplifies composition, maintenance,
|
|
collaboration, and publication, it also enables authors to
|
|
apply a wide range of tools for composition assistance.
|
|
This feature must be exploited if text processing is going
|
|
to fulfill its original promise to significantly assist
|
|
scholarly composition and become more than just improved
|
|
typing. [4]
|
|
|
|
5.1 Logical Tags
|
|
|
|
Table 1 describes the major HTML logical tags.
|
|
|
|
-----------------------------------------------------------------
|
|
Table 1. Major Logical Tags
|
|
-----------------------------------------------------------------
|
|
|
|
<EM> </EM > Emphasis, usually italics.
|
|
<STRONG> </STRONG> Strong emphasis, usually bold.
|
|
<DFN> </DFN> Definition term, usually bold.
|
|
<CITE> </CITE> Citation, usually italics.
|
|
<BLOCKQUOTE></BLOCKQUOTE> Quotation, usually italics.
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 13 +
|
|
|
|
To see how logical tags are used, let's add a couple of them to
|
|
the example home page from Figure 3. Figure 4 shows the modified
|
|
home page.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 4. Home Page With Logical Tags
|
|
-----------------------------------------------------------------
|
|
|
|
<TITLE>Jeff's Home Page</TITLE>
|
|
<H1>Jeff's Home on the Net</H1>
|
|
Your <EM>home page</EM> may include links to other
|
|
information sources on the network, information about
|
|
yourself, and even your photograph. HTML provides the
|
|
flexibility of crafting a <STRONG>toolbox of networked
|
|
resources</STRONG> that meets your needs.
|
|
|
|
<BLOCKQUOTE>If a man does not keep pace with his companions,
|
|
perhaps it is because he hears a different drummer. Let him
|
|
step to the music which he hears, however measured or far
|
|
away.</BLOCKQUOTE>
|
|
|
|
<CITE>Henry David Thoreau. Walden, 1854.</CITE>
|
|
-----------------------------------------------------------------
|
|
|
|
Additional logical tags that provide information about the text
|
|
contained in the tagged element are <CODE> for examples of
|
|
computer programming code, <KBD> for examples of text typed from
|
|
a keyboard, <SAMP> to indicate a sample sequence of characters,
|
|
and <VAR> to specify the enclosed text as the name of a variable.
|
|
Appendix A describes these tags.
|
|
|
|
5.2 Physical Tags
|
|
|
|
The BOLD tag (<B>), which is a physical tag, most closely
|
|
corresponds to the STRONG tag (<STRONG>), which is a logical tag;
|
|
and the ITALICS tag (<I>), which is a physical tag, corresponds
|
|
to the EMPHASIS tag (<EM>), which is a logical tag. However, it
|
|
should not be assumed that text marked with the EMPHASIS tag will
|
|
be in italics. The physical tags can be used to force the
|
|
desired type of presentation. Of course, the display device must
|
|
be capable of presenting characters in the designated format.
|
|
For instance, on a character-screen terminal, text marked with
|
|
the ITALICS tag may actually be rendered as bold because italics
|
|
cannot be displayed on such a monitor.
|
|
Whenever a Web browser encounters tags that it does not
|
|
understand, those tags will be ignored; however, the text within
|
|
the tags will still be displayed. Some primitive Web browsers do
|
|
not understand logical tags and simply display text enclosed
|
|
within logical tags without any highlighting.
|
|
|
|
+ Page 14 +
|
|
|
|
The seemingly conflicting recommendation to use logical tags
|
|
over physical tags--even when all Web browsers do not yet support
|
|
the former--reflects the early stage of development of HTML and
|
|
the Web itself. As Web technology matures, more scalable
|
|
solutions will evolve. The movement away from physical tags
|
|
towards logical tags reflects this ongoing evolution.
|
|
|
|
5.3 PREFORMATTED TEXT Tag (<PRE>)
|
|
|
|
The PREFORMATTED TEXT tag (<PRE>) instructs Web browsers to
|
|
preserve the formatting (i.e., character and line spacing) of the
|
|
enclosed text and present it in a standard, monospace font. This
|
|
tag is used for text that would become unintelligible if
|
|
displayed in a proportional font. Because HTML does not
|
|
currently provide for the display of tables or matrices, the
|
|
preformatted text element serves as an easy way to display
|
|
tabular information in HTML documents.
|
|
Since the PREFORMATTED TEXT tag retains the hard returns of
|
|
the original ASCII text, neither the PARAGRAPH tag nor any of the
|
|
highlighting tags should be used within preformatted text;
|
|
however, hypertext links may be included.
|
|
Actually, the easiest way to create an HTML document is
|
|
through the use of the PREFORMATTED TEXT tag. By inserting <PRE>
|
|
at the beginning of a document and </PRE> at the end of a
|
|
document, you can create an HTML file. This quick and dirty
|
|
approach creates correspondingly unattractive, but readable,
|
|
documents. As with all HTML documents, the file extension must
|
|
be ".html" (or ".htm" if the documents are being served from a
|
|
Microsoft DOS or Windows machine).
|
|
|
|
5.4 LINE BREAK Tag (<BR>)
|
|
|
|
It's often difficult for new HTML users to figure out how to
|
|
control the line spacing of a document. Many tags, such as
|
|
HEADING tags, add an extra space below their end tags. If you
|
|
simply want to simulate the appearance of a carriage return, use
|
|
the LINE BREAK tag (<BR>). Figure 5 illustrates the use of the
|
|
LINE BREAK tag.
|
|
|
|
+ Page 15 +
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 5. LINE BREAK Tag Example
|
|
-----------------------------------------------------------------
|
|
|
|
<P>Jeff Barry<BR>
|
|
Cooperative Information Services Librarian<BR>
|
|
The University of Tennessee Libraries<BR>
|
|
Knoxville, Tennessee<BR>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
The LINE BREAK tag is useful in displaying addresses. Notice
|
|
that if the LINE BREAK tag was omitted, the Web client would
|
|
display the lines as if they flowed together without any
|
|
separation. Inserting a regular carriage return in an ASCII text
|
|
file has no significance on the way an HTML document is displayed
|
|
(except in preformatted text).
|
|
|
|
5.5 HORIZONTAL RULE Tag (<HR>)
|
|
|
|
Many document authors take advantage of the HORIZONTAL RULE tag
|
|
(<HR>) to provide a visual means of dividing their documents.
|
|
Whenever a Web browser encounters a HORIZONTAL RULE tag, it
|
|
displays a horizontal divider line across the screen.
|
|
|
|
Figure 6 presents an example of the HORIZONTAL RULE tag.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 6. HORIZONTAL RULE Tag Example
|
|
-----------------------------------------------------------------
|
|
|
|
<TITLE>Jeff's Home Page</TITLE>
|
|
<H1>Jeff's Home on the Net</H1>
|
|
Your <EM>home page</EM> may include links to other
|
|
information sources on the network, information about
|
|
yourself, and even your photograph. HTML provides the
|
|
flexibility of crafting a <STRONG>toolbox of networked
|
|
resources</STRONG> that meets your needs.
|
|
<HR>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 16 +
|
|
|
|
6.0 Creating Hypertext Links
|
|
|
|
One of the most exciting aspects of HTML is its ability to create
|
|
hypertext links. Links can be created to items within the same
|
|
document, to other documents on the same server, or to any
|
|
document on the Internet. Links are used to relate one document
|
|
to another. The format for specifying a hypertext link consists
|
|
of at least three parts: the ANCHOR tag, the network address of
|
|
the document to be linked, and the text to be displayed in the
|
|
formatted document. Links are anchored to specific text within a
|
|
document.
|
|
|
|
6.1 ANCHOR Tag (<A>)
|
|
|
|
The first step in creating a hypertext link is to determine the
|
|
text that will represent the link. The text provided for the
|
|
link should give the user an indication about the content of the
|
|
link.
|
|
Since many HTML documents also serve as printed
|
|
documentation, hypertext links should provide meaning and
|
|
readability in the context of the surrounding text without
|
|
incorporating computer specific actions such as clicking a mouse.
|
|
Don't create a link that says: "For a hypermedia interface to the
|
|
Library of Congress' 1492: An Ongoing Voyage Exhibit, click
|
|
here." Rather, make a link that says: "A hypermedia interface to
|
|
the Library of Congress' 1492: An Ongoing Voyage Exhibit is
|
|
available."
|
|
Enclose text within an ANCHOR tag to designate it as a
|
|
hypertext link. The text between the starting tag (<A>) and
|
|
ending tag (</A>) will be displayed by the Web browser with
|
|
special emphasis, usually underlined and in a separate color from
|
|
the other text. Using the ANCHOR tag alone, however, does not
|
|
constitute a valid link. A network address, in the form of a
|
|
Uniform Resource Locator (URL), that specifies the document to be
|
|
retrieved must be included as part of the hypertext link.
|
|
In HTML, many start tags can have optional attributes (a
|
|
description of attributes for all tags is provided in Appendix
|
|
A). An attribute consists of a name, followed by an equal sign,
|
|
followed by a value for that attribute. The value of the
|
|
attribute should be enclosed in double quotes. An important
|
|
attribute of the starting ANCHOR tag is named HREF (think of
|
|
hypertext reference). The value of HREF is the location of the
|
|
document to be retrieved.
|
|
|
|
+ Page 17 +
|
|
|
|
Figure 7 shows an example of an ANCHOR tag with a HREF.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 7. ANCHOR Tag Example
|
|
-----------------------------------------------------------------
|
|
|
|
<A HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">
|
|
1492: An Ongoing Voyage</A>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
Notice that the value of the HREF attribute is always in the form
|
|
of a URL.
|
|
|
|
6.2 Uniform Resource Locators (URLs)
|
|
|
|
The Web uses Uniform Resource Locators (URLs) as its standard way
|
|
of referencing information on the Internet. The use of a
|
|
standard addressing scheme by authors of HTML documents allows
|
|
computer programs to interpret the address, use the appropriate
|
|
Internet protocol (e.g., FTP, Telnet, and HTTP), and automate the
|
|
retrieval of the specified item with the "click of a button."
|
|
Two forms of specifying URL syntax are available to authors:
|
|
absolute URLs that contain the full addressing syntax and partial
|
|
URLs.
|
|
|
|
6.2.1 Absolute URLs
|
|
|
|
Absolute URLs are the most common type of URL, and they should
|
|
always be used to link to documents on Gopher servers. A URL is
|
|
divided into three parts: the protocol, the machine name, and the
|
|
path (i.e., protocol://machine.name[:port]/path). The first part
|
|
of the URL names the Internet protocol used for accessing the
|
|
document, such as "ftp," "gopher," "http," "telnet," and other
|
|
supported protocols. The second part of the URL identifies the
|
|
name of the document server, such as "sunsite.unc.edu." (Some
|
|
servers run protocols on nonstandard ports; if so, the alternate
|
|
port number, preceded by a colon, follows the machine name.) The
|
|
final part of the URL represents the path of the document to be
|
|
retrieved. Separating the protocol from the machine name in the
|
|
URL is a colon (:) and two forward slashes (//). Separating the
|
|
machine name from the path is one forward slash (/).
|
|
|
|
Figure 8 presents an example of a URL.
|
|
|
|
+ Page 18 +
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 8. Example URL
|
|
-----------------------------------------------------------------
|
|
|
|
http://sunsite.unc.edu/expo/1492.exhibit/Intro.html
|
|
| | | | |
|
|
| | | | |
|
|
| +--------------+ +--------------------------+
|
|
| | |
|
|
Protocol Machine Name Path
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
Occasionally, a reference to a URL has no path (e.g.,
|
|
http://www.cityscape.co.uk/). In most instances, this will be an
|
|
acceptable URL. Depending upon the configuration of the
|
|
particular Web server at that destination, either an index of
|
|
files in the server's root directory will be generated or an HTML
|
|
document named "index.html" will be retrieved. The document
|
|
named "index.html" may not be an index per se, but a default home
|
|
page that is delivered whenever a path is not specified.
|
|
|
|
6.2.1.1 HTTP URL
|
|
|
|
The URL in Figure 9 specifies the protocol as the HyperText
|
|
Transfer Protocol ("http"). The document is located on the
|
|
machine with the host name of "sunsite.unc.edu." The
|
|
"expo/1492.exhibit/Intro.html" part of the URL represents the
|
|
path of that document on the Web server.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 9. Example HTTP URL
|
|
-----------------------------------------------------------------
|
|
|
|
http://sunsite.unc.edu/expo/1492.exhibit/Intro.html
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 19 +
|
|
|
|
6.2.1.2 Gopher URL
|
|
|
|
Figure 10 is an example of a URL pointing to a Gopher server.
|
|
This particular server is hosted by the University of Tennessee
|
|
Libraries. The URL points to the Smoky Mountain Database, which
|
|
contains information about biodiversity and environmental issues
|
|
in the Appalachians.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 10. Example Gopher URL
|
|
-----------------------------------------------------------------
|
|
|
|
gopher://www.lib.utk.edu/11/Information-by-Subject/S%3a/smokies
|
|
| | | | |
|
|
| | | | |
|
|
| +-------------+ +------------------------------------+
|
|
| | |
|
|
Protocol Machine Name Path
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
6.2.1.3 Telnet URL
|
|
|
|
Since the Telnet protocol opens an interactive terminal session,
|
|
a path is not needed. The URL in Figure 11 connects via Telnet
|
|
to the CARL UnCover system.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 11. Example Telnet URL
|
|
-----------------------------------------------------------------
|
|
|
|
telnet://database.carl.org/
|
|
| | |
|
|
| | |
|
|
| +-----------------+
|
|
| |
|
|
Protocol Machine Name
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 20 +
|
|
|
|
6.2.1.4 Anonymous FTP URL
|
|
|
|
Documents that reside an anonymous FTP servers can be accessed by
|
|
use of a URL like the one in Figure 12.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 12. Example Anonymous FTP URL
|
|
-----------------------------------------------------------------
|
|
|
|
ftp://ftp.cni.org/pub/LITA/tiip-forum/proceedings.html
|
|
| | | | |
|
|
| | | | |
|
|
| +---------+ +----------------------------------+
|
|
| | |
|
|
Protocol Machine Name Path
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
It is also possible to link to subdirectories rather than to a
|
|
specific document. For example, the URL in Figure 13 links to a
|
|
subdirectory that contains the document Principles for the
|
|
Development of the National Information Infrastructure in various
|
|
formats. The HTML document returned by this link is an index of
|
|
the files in that subdirectory. Each file name in the directory
|
|
listing becomes a link to the specific document. In this manner,
|
|
the Web provides an easy way of retrieving documents from
|
|
anonymous FTP servers.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 13. Example Anonymous FTP Subdirectory URL
|
|
-----------------------------------------------------------------
|
|
|
|
<P>The proceedings <A HREF="ftp://ftp.cni.org/pub/LITA/tiip-
|
|
forum/proceedings.html">Principles for the Development of the
|
|
National Information Infrastructure</A> from ALA's
|
|
Telecommunications and Information Infrastructure Policy Forum
|
|
are available on the Internet.
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 21 +
|
|
|
|
6.2.2 Partial (or Relative) URLs
|
|
|
|
A partial URL specifies the path of a link relative to the
|
|
originating document. When encountering a partial URL, the Web
|
|
software assumes that the protocol and the machine name for the
|
|
destination of the hypertext link are the same as that of the
|
|
document that contains the link. (See section 6.3 for examples
|
|
of partial URLs.)
|
|
|
|
6.3 Linking to Other Documents on the Same Server
|
|
|
|
Hypertext documents on the Web often consist of links among
|
|
multiple files on the same server. The following example shows
|
|
how partial URLs can be used to create hypertext links to
|
|
documents on the same server. The originating document, the
|
|
homepage.html file, is in the webfiles directory. The
|
|
destination links are the htmlguides.html file, which is also in
|
|
the webfiles directory; the editors.html file, which is in the
|
|
tools subdirectory of webfiles; and the userguide.html file,
|
|
which is in the lbryfiles directory. (Note that the lbryfiles
|
|
directory is not a subdirectory of webfiles). The directory
|
|
structure for the files is shown in Figure 14, and the marked up
|
|
text of the homepage.html file is shown in Figure 15.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 14. Example Directory Structure
|
|
-----------------------------------------------------------------
|
|
|
|
+---------------------------------------+
|
|
| |
|
|
webfiles lbryfiles
|
|
| |
|
|
+------------+-----------------+ userguide.html
|
|
| | |
|
|
| | |
|
|
homepage.html htmlguides.html tools
|
|
|
|
|
editors.html
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 22 +
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 15. Contents of Homepage.html
|
|
-----------------------------------------------------------------
|
|
|
|
<P>More information about creating documents for the Web can be
|
|
found in <A HREF="htmlguides.html">Guides to HTML</A>. To
|
|
facilitate the authoring of HTML documents a number of <A
|
|
HREF="tools/editors.html">HTML editors</A> are being developed.
|
|
<A HREF="../lbryfiles/userguide.html">Ways of Using Networked
|
|
Resources</A> in the library is another document for learning to
|
|
use the Internet.
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
The path of a URL is a hierarchical "naming space" similar to a
|
|
directory and file name structure. The conventions used for
|
|
referencing names are patterned after the UNIX file system. Each
|
|
forward slash (/) in the URL's path statement is a division of
|
|
the hierarchy. Items to the left of a forward slash have a
|
|
greater precedence in the hierarchy than items to the right of
|
|
the forward slash. For example, in Figure 14, editors.html is a
|
|
part of tools which, in turn, is a part of webfiles. A
|
|
convention for navigating the UNIX filesystem is that following
|
|
the change directory command with a space and two periods (cd
|
|
..) moves the user up one level in the directory hierarchy.
|
|
Consequently, the user could type "cd ../new_directory_name" to
|
|
move up one directory level and then move into a new directory
|
|
that branches off of that same level. This capability can be
|
|
expressed in relative URLs, as shown in the example of moving
|
|
from the document homepage.html to the document userguide.html
|
|
(../lbryfiles/userguide.html).
|
|
The importance of hierarchical naming and relative URLs is
|
|
that their use allows HTML documents to be constructed on one
|
|
machine and easily moved to another. This capability is very
|
|
useful for authors who do not have user access to a Web server.
|
|
Through the use of partial URLs, it is quite common for documents
|
|
to be written and marked up on a PC (or Macintosh) and then FTP'd
|
|
to a UNIX machine functioning as a Web server. For instance,
|
|
four of the Library of Congress' Web exhibits text files were
|
|
actually written in Washington, D.C.; the HTML markup of these
|
|
files was done in the Netherlands and in Tennessee; and the
|
|
resulting HTML files were transferred to a Web server in North
|
|
Carolina. The use of relative URLs made this world-wide endeavor
|
|
much easier.
|
|
|
|
+ Page 23 +
|
|
|
|
6.4 Fragment Identifiers
|
|
|
|
Fragment identifiers are established by using the NAME attribute
|
|
of the ANCHOR (<A>) tag. Normally, the value of the NAME
|
|
attribute is a mnemonic for the anchored text. Whenever the NAME
|
|
attribute is used, the anchored text can be the destination of a
|
|
link, and it is a means of identifying a fragment of the
|
|
document. It is possible to create links to specific sections of
|
|
a document only when those sections have been anchored and a
|
|
value has been given for the NAME attribute. It is a good idea
|
|
to use the NAME attribute so that future authors can create links
|
|
to specific areas of your documents. (Of course, regular
|
|
hypertext links to the documents can always be created.)
|
|
The use of the NAME attribute also permits the creation of
|
|
links within the same document. This can be done at the top of a
|
|
large file to permit users to quickly access relevant sections of
|
|
the document rather than forcing users to scroll through the
|
|
entire document.
|
|
|
|
Figure 16 shows example fragment identifiers.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 16. Example Fragment Identifiers
|
|
-----------------------------------------------------------------
|
|
|
|
<P>The <A HREF="documentname#coombs">article by Coombs et al.</A>
|
|
is an excellent overview of markup practices for scholarly texts.
|
|
|
|
<P>More text could go here. Notice how fragment identifiers can
|
|
be used to create footnotes.
|
|
|
|
<HR>
|
|
|
|
<P><A NAME="coombs">James H. Coombs, Allen H. Renear, and Steven
|
|
J. DeRose </A>, "Markup Systems and the Future of Scholarly Text
|
|
Processing," Communications of the ACM 30 (November 1987): 933-
|
|
947.
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
7.0 IMG Tag (<IMG>)
|
|
|
|
One of the most distinctive aspects of many HTML documents is the
|
|
use of images as hypertext links and as decorative accents.
|
|
Images that are placed within HTML documents are called "in-lined
|
|
images." Supported image formats include GIF, JPEG, and bitmaps.
|
|
Images can be scanned photos or original graphics created with a
|
|
paint program.
|
|
|
|
+ Page 24 +
|
|
|
|
The IMG tag (<IMG>) indicates that an image should be
|
|
included in an HTML document. The IMG tag has three attributes.
|
|
The most important attribute is SRC (think of source), which has
|
|
as its value the URL of the image. The SRC value may be a
|
|
partial or absolute URL depending upon the location of the image.
|
|
The second attribute of the IMG tag is ALT. The value of ALT is
|
|
the text that should be displayed in web browsers that do not
|
|
support in-lined images, such as Lynx. The third attribute is
|
|
ALIGN, which indicates whether to align the text alongside the
|
|
top, middle, or bottom of the image when the document is
|
|
displayed. Legal values for ALIGN are "top," "middle," or
|
|
"bottom"; the default is "bottom."
|
|
|
|
Figure 17 shows the use of the IMG tag.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 17. Example IMG Tag
|
|
-----------------------------------------------------------------
|
|
|
|
<IMG SRC="machu_p.gif" ALT="Ruins at Machu Pitthu, Peru">
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
When using an image as a link, the IMG tag is inserted alongside
|
|
or in place of the text of the anchor. For example, Figure 18
|
|
presents anchor links from a small image to a larger photo of
|
|
that image.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 18. Example In-lined Image Linked to a Larger Image
|
|
-----------------------------------------------------------------
|
|
|
|
<A HREF="../full-images/lg.machu_p.gif"><IMG
|
|
SRC="machu_p.gif">Ruins at Machu Pitthu, Peru</A>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
Whenever a user clicks the small image, the link retrieves the
|
|
larger one. Notice that the text is also a link to the image so
|
|
that the user may click on either the image or the text to
|
|
activate the link. Browsers usually display images functioning
|
|
as links with a thicker border than those that surround
|
|
decorative images. A frequent mistake that HTML authors make
|
|
with this kind of link is to forget to add the ending ANCHOR tag
|
|
(</A>).
|
|
|
|
+ Page 25 +
|
|
|
|
The thumbnail images that are an essential part of so many
|
|
Web documents can be created with a number of tools. Most image
|
|
viewers include a way to reduce the size of an image. If
|
|
scanning from a photo, one might want to consider using a Kodak
|
|
Photo CD, which provides five different resolutions (one of which
|
|
is excellent for Web documents).
|
|
|
|
8.0 Lists
|
|
|
|
The hierarchical structure of the Gopher software has proven to
|
|
be very useful, and authors can retain a hierarchical menu when
|
|
creating Web documents. A drawback of Gopher is that only
|
|
limited information can be provided within the hierarchical menu
|
|
itself. Readers normally have to select a Gopher menu item and
|
|
then view a README file (or some other documenting file) to
|
|
determine the system's scope. Since HTML provides the capability
|
|
for hypertext links to be included within text, it's easy to
|
|
provide some descriptive information about a document before the
|
|
link is selected. In some ways, one can look at the Web as
|
|
simply extending the capabilities of Gopher to the next logical
|
|
level.
|
|
A good example of using related text with a hypertext link
|
|
is NCSA's "What's New" pages (see http://www.ncsa.uiuc.edu/
|
|
SDG/Software/Mosaic/Docs/whats-new.html). The entries on the
|
|
"What's New" page are simply separated into paragraphs in order
|
|
to create a list. Another approach would be to use the HTML list
|
|
tags.
|
|
|
|
8.1 UNORDERED LIST Tag (<UL>)
|
|
|
|
In HTML, lists are simply sequences of paragraphs that may be
|
|
prefaced with special characters. A common means of organizing
|
|
home pages is to separate the different items into an UNORDERED
|
|
LIST. A bullet preceding each item calls attention to that item.
|
|
The tag to begin an UNORDERED LIST is <UL>. Think of "UL"
|
|
as representing "unordered list." The tag to end an UNORDERED
|
|
LIST is </UL>. Each item in a list must be preceded by an <LI>
|
|
tag. This tag represents the list entry. A list can contain
|
|
many separate items. The <LI> tag does not require an end tag.
|
|
In Figure 19, hypertext links to documents on the Internet
|
|
are presented as a UNORDERED LIST.
|
|
|
|
+ Page 26 +
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 19. Example UNORDERED LIST
|
|
-----------------------------------------------------------------
|
|
|
|
<UL>
|
|
<LI> Visit the <A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage</A> Exhibit by the Library of Congress to learn
|
|
about the early exploration of the Western Hemisphere.
|
|
|
|
<LI> Biodiversity and environmental issues in the Appalachians
|
|
are the themes of the <A
|
|
HREF="gopher://www.lib.utk.edu/11/Information-by-
|
|
Subject/S%3a/smokies">Smoky Mountain Database</A>.
|
|
|
|
<LI>The <A HREF="telnet://database.carl.org/">CARL
|
|
Corporation</A> provides an excellent interactive service
|
|
accessible over the Internet.
|
|
|
|
<LI> The proceedings <A HREF="ftp://ftp.cni.org/pub/LITA/tiip-
|
|
forum/proceedings.html">Principles for the Development of the
|
|
National Information Infrastructure</A> from ALA's
|
|
Telecommunications and Information Infrastructure Policy Forum
|
|
are available on the Internet.
|
|
</UL>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
8.2 MENU LIST Tag (<MENU>)
|
|
|
|
A MENU LIST is appropriate for very short items. A MENU LIST
|
|
groups the items more closely together, and there is normally
|
|
only one item per line. Because of the line length limitations,
|
|
a MENU LIST can be considered to be the Web's equivalent of a
|
|
Gopher hierarchical menu. To start a MENU LIST, use the <MENU>
|
|
tag. Each item in the menu list is designated by the <LI> tag.
|
|
To close a MENU LIST, use the </MENU> tag.
|
|
|
|
+ Page 27 +
|
|
|
|
Figure 20 shows an example MENU LIST.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 20. Example MENU LIST
|
|
-----------------------------------------------------------------
|
|
|
|
<MENU>
|
|
<LI><A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage Exhibit</A>
|
|
<LI><A HREF="gopher://www.lib.utk.edu/11/Information-by-
|
|
Subject/S%3a/smokies">Smoky Mountain Database</A>
|
|
<LI><A HREF="telnet://database.carl.org/">CARL Corporation</A>
|
|
<LI><A HREF="ftp://ftp.cni.org/pub/LITA/tiip-
|
|
forum/proceedings.html">Principles for the Development of the
|
|
National Information Infrastructure</A>.
|
|
</MENU>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
8.3 ORDERED LIST Tag (<OL>)
|
|
|
|
A third type of HTML list is the ORDERED LIST. The tag to begin
|
|
an ORDERED LIST is <OL>. Each item in the list is designated by
|
|
the <LI> tag. When an ORDERED LIST is displayed in a Web
|
|
browser, the <LI> tag is replaced by an Arabic numeral. The list
|
|
items are numbered in the proper order. Authors do not need to
|
|
enter the item number when creating an ordered list; HTML ensures
|
|
that Web browsers display the numbers automatically. A key
|
|
benefit of an ORDERED LIST is that items can be added in the
|
|
middle of the list without the author having to manually correct
|
|
the numerical order. The end of an ORDERED LIST is identified by
|
|
the </OL> tag.
|
|
|
|
+ Page 28 +
|
|
|
|
Figure 21 illustrates a ORDERED LIST.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 21. Example ORDERED LIST
|
|
-----------------------------------------------------------------
|
|
|
|
<H1>Creating Hypertext Links in HTML</H1>
|
|
<OL>
|
|
<LI>Identify the destination of links.
|
|
<LI>Determine text to be anchored as the start of a link.
|
|
<LI>Surround text with anchor tags.
|
|
<LI>Insert within the starting anchor tag the URL of the link's
|
|
destination as the value of the HREF attribute.
|
|
<LI>Use the NAME attribute so that the anchored text may also be
|
|
the destination of a link.
|
|
<LI>Be sure to close the anchor with the end tag.
|
|
<LI>Test the link in a browser.
|
|
</OL>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
The only differences in the markup for an UNORDERED and ORDERED
|
|
LIST are the tags that open and close the list. Use <UL></UL>
|
|
for an UNORDERED List and <OL></OL> for an ORDERED List.
|
|
|
|
8.4 DEFINITION LIST Tag (<DL>)
|
|
|
|
A DEFINITION LIST provides information in a glossary format. As
|
|
with other types of lists, a DEFINITION LIST begins and ends with
|
|
a unique tag. To begin a DEFINITION LIST, use the <DL> tag.
|
|
Each term in the list is identified by the <DT> tag. In essence,
|
|
the <DT> tag serves the same function as the <LI> tag in an
|
|
ORDERED or an UNORDERED LIST. A DEFINITION LIST also needs a
|
|
tag to identify the definition of the term itself: the <DD> tag.
|
|
|
|
+ Page 29 +
|
|
|
|
Figure 22 shows a DEFINITION LIST.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 22. Example DEFINITION LIST
|
|
-----------------------------------------------------------------
|
|
|
|
<H1>Glossary</H1>
|
|
|
|
<DL>
|
|
<DT>URL<DD>Uniform Resource Locator is the standard used to refer
|
|
to documents and their locations on the Internet.
|
|
|
|
<DT>NCSA<DD>The National Center for Supercomputing Applications
|
|
created the Mosaic browser, which was instrumental in bringing
|
|
greater attention to the World-Wide Web.
|
|
|
|
<DT>WWW<DD>The World-Wide Web, originating out of CERN in
|
|
Switzerland, provides hypertext on the Internet through the use
|
|
of HTTP and HTML.
|
|
|
|
<DT>SGML<DD>The Standard Generalized Markup Language is an
|
|
international standard that describes the structure of a
|
|
document.
|
|
|
|
<DT>DTD<DD>A Document Type Definition, specified according to the
|
|
rules of SGML (e.g., HTML), describes a document's structure for
|
|
the purposes of a particular application such as Web.
|
|
|
|
<DT>CERN<DD>The Swiss organization that started the World-Wide
|
|
Web initiative. The words of the acronym translate into English
|
|
as the European Laboratory for Particle Physics.
|
|
</DL>
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
Neither the <DT> nor <DD> tags require end tags. Remember to use
|
|
the <DT> and <DD> tags in pairs. Be sure to use the proper
|
|
closing tag </DL> for the list.
|
|
|
|
8.5 Nested Lists
|
|
|
|
An extremely useful HTML feature is the ability to nest lists. A
|
|
nested list can serve as an outline or as a way to show multiple
|
|
levels of a hierarchical structure of documents. The nested list
|
|
is most often used with an UNORDERED LIST. Depending on the
|
|
capabilities of the Web browser, the nested items will be
|
|
displayed with different types of bullets from items at higher
|
|
levels of the hierarchy.
|
|
|
|
+ Page 30 +
|
|
|
|
9.0 Advanced HTML Features
|
|
|
|
The previous sections of this paper described the tags needed to
|
|
create usable HTML documents; this section provides information
|
|
about additional structural elements of HTML.
|
|
|
|
9.1 PROLOGUE
|
|
|
|
The PROLOGUE appears at the very beginning of an HTML file, and
|
|
it identifies that file as being an HTML document. The primary
|
|
purpose of the PROLOGUE is to allow software to distinguish HTML
|
|
documents from other types of SGML documents. All HTML documents
|
|
written according to the current HTML specifications have the
|
|
PROLOGUE shown in Figure 23.
|
|
|
|
-----------------------------------------------------------------
|
|
Figure 23. Standard PROLOGUE
|
|
-----------------------------------------------------------------
|
|
|
|
<!doctype html public "-//W30//DTD W3 HTML 2.0//EN">
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
9.2 The Hierarchy of an HTML Document
|
|
|
|
An HTML document is composed of a hierarchy of structural
|
|
elements. At the top of the hierarchy is the HTML element
|
|
itself. This element encompasses all other elements; therefore,
|
|
the <HTML> tag comes at the beginning of the document (just after
|
|
the PROLOGUE) and the </HTML> tag appears at the end of the
|
|
document. Below the HTML element in the hierarchy are the HEAD
|
|
and BODY elements. The HEAD includes elements that describe the
|
|
document, such as TITLE. Additional elements (BASE, ISINDEX,
|
|
LINK, and NEXTID) of the HEAD are described in Appendix A. While
|
|
the HEAD and related elements are useful to software that
|
|
processes HTML documents, their use is not required. The BODY
|
|
tag identifies the primary information content of the document.
|
|
|
|
+ Page 31 +
|
|
|
|
9.3 Special Characters
|
|
|
|
Non-ASCII characters can be displayed using HTML. To represent
|
|
these characters in an HTML document file, use an ampersand (&)
|
|
followed by the designated letter(s) for the desired character.
|
|
The ampersand instructs the Web browser to ignore the regular
|
|
meaning of a letter and to insert the new character. A full list
|
|
of special characters is available from the following URL:
|
|
http://info.cern.ch/hypertext/WWW/MarkUp/ISOlat1.html.
|
|
|
|
10.0 Organizing HTML Documents
|
|
|
|
Understanding how to use HTML markup tags is only one aspect of
|
|
creating an effective hypermedia resource; organizing and linking
|
|
the documents is far more time-consuming. Unlike printed
|
|
materials designed to be read sequentially, hypertext documents
|
|
can be read in an unspecified order. A common effect hypertext
|
|
has on readers is the sensation of being "lost in hyperspace."
|
|
Without any navigational aids or clues from the author, readers
|
|
may lose their sense of orientation as to which documents should
|
|
be read next and which documents have already been read.
|
|
All Web clients should provide some sort of navigational
|
|
features, such as backtracking and history. Backtracking allows
|
|
the user to go back to each previous document until he or she has
|
|
regained a "sense of place." The history feature provides a list
|
|
of documents that the reader has visited. Clicking on any of the
|
|
documents listed in the history should return the reader to that
|
|
point. However, HTML document authors should be aware that each
|
|
Web browser may implement these features differently and, in some
|
|
cases, the navigational aids of a browser may not be fully
|
|
reliable. When providing a large number of related hypertext
|
|
documents, it is always wise to embed navigational links directly
|
|
into the documents. Authors will often provide links in the form
|
|
of images for moving forward and backward among related
|
|
documents. These links serve as a safeguard against the
|
|
possibility that a browser may not support the proper means of
|
|
navigation. A good example of this safeguard is the HTML version
|
|
of "Entering the World-Wide Web: A Guide to Cyberspace"
|
|
(http://www.eit.com/web/www.guide/). In addition to providing
|
|
clues as to where to go next, document authors should always
|
|
provide the reader with a way to escape out of a series of
|
|
documents without using the backtrack button. Most often, this
|
|
escape feature is in the form of a link back to the site's home
|
|
page.
|
|
|
|
+ Page 32 +
|
|
|
|
Author-supplied navigational aids may take other forms, such
|
|
as a guided tour that suggests the order in which documents
|
|
should be read. The Library of Congress' Rome Reborn Exhibit
|
|
(http://sunsite.unc.edu/expo/vatican.exhibit/
|
|
Vatican.exhibit.html) demonstrates the effects of using a
|
|
"virtual tour guide." Another approach is to provide an outline
|
|
that provides direct links to selected documents. This outline
|
|
technique simply nests links (this strategy was employed for the
|
|
Library of Congress exhibits): see the outline documents for
|
|
"1492: An Ongoing Voyage" (http://sunsite.unc.edu/expo/1492.
|
|
exhibit/overview.html) and the Dead Sea Scrolls Exhibit (http:
|
|
//sunsite.unc.edu/expo/deadsea.scrolls.exhibit/overview.html).
|
|
One advanced feature of HTML is the ability to create
|
|
graphical images and then specify certain areas of the image as
|
|
links to different documents with the ISMAP tag. The University
|
|
of Tennessee's Office of Research Services has created an HTML
|
|
document that effectively illustrates the use of ISMAP
|
|
capabilities (http://solar.rtd.utk.edu/default.html).
|
|
|
|
11.0 HTML and SGML
|
|
|
|
HTML is only one type of markup language based on the Standard
|
|
Generalized Markup Language (SGML). As an international
|
|
standard, SGML provides a way of creating markup languages
|
|
tailored for different types of documents. The defining
|
|
characteristic of documents marked up using HTML is that they may
|
|
contain hypertext links to other documents located on a computer
|
|
network. The "grammar" (or set of permissible tags and their
|
|
uses) for any SGML-based markup language is defined in a Document
|
|
Type Definition (DTD). In the strictest sense, HTML is not a
|
|
markup language, but a specific DTD for SGML. Just as HTML
|
|
serves the purposes of hypermedia, other DTDs exist for other
|
|
purposes. For example, the Text Encoding Initiative (TEI) has
|
|
produced a DTD for the markup of humanities text files. It is
|
|
possible for gateways to be developed between one DTD and another
|
|
DTD; however, any functionality found in one DTD, but not in the
|
|
other, would be lost as the document traversed the gateway.
|
|
|
|
+ Page 33 +
|
|
|
|
12.0 What's Ahead for HTML: Solidifying the Standard
|
|
|
|
After the issuance of the HTML specification as an Internet Draft
|
|
in June 1993, the release of several Web browsers resulted in a
|
|
dramatic increase of HTML usage as well as the emergence of new
|
|
Web capabilities. As it became evident that the 1993 HTML
|
|
specification was not providing certain features that authors
|
|
needed, an effort to extend HTML was begun. The new
|
|
specification that evolved from this effort was known as HTML+.
|
|
However, at the same time, Web browser developers faced
|
|
increased difficulties in interpreting the HTML tags being used
|
|
by authors; many HTML documents on the Web failed to even comply
|
|
with the original specification.
|
|
Some of the conditions that resulted in non-conformance with
|
|
the HTML standard were widespread use of rapidly changing
|
|
freeware that did not fully support all HTML elements, unclear
|
|
(and sometimes conflicting) documentation for authors and
|
|
software implementors about how to use and interpret HTML tags,
|
|
and authors' persistence in validating HTML documents with one
|
|
particular Web browser. As a result, some HTML documents only
|
|
looked good on a specific browser. For many users, HTML was
|
|
defined not by its specification, but by whatever features their
|
|
favorite browser supported.
|
|
With the advent of commercial Web software and the wide
|
|
exposure that the Web garnered in many publications, the
|
|
scalability of the Web was in jeopardy without a strengthening of
|
|
the HTML specification to define a stable standard for current
|
|
practice. Based on discussions on Internet mailing lists devoted
|
|
to Web and the First International WWW Conference in Geneva (held
|
|
in May 1994), a mechanism for recasting the HTML specification
|
|
was established. The designation HTML+ was dropped in preference
|
|
of a means for identifying different levels of conformance to the
|
|
HTML specification.
|
|
|
|
+ Page 34 +
|
|
|
|
Table 2 presents the HTML levels of conformance in HTML, Version
|
|
2.0.
|
|
|
|
-----------------------------------------------------------------
|
|
Table 2. HTML Conformance Levels
|
|
-----------------------------------------------------------------
|
|
|
|
Level 0 Indicates the minimum conformance level.
|
|
|
|
Level 1 Indicates Level 0 features, plus features such as
|
|
highlighting and images.
|
|
|
|
Level 2 Includes all Level 0 and Level 1 features, plus
|
|
forms.
|
|
|
|
-----------------------------------------------------------------
|
|
|
|
HTML elements that conform to Level 0 are implemented in every
|
|
browser and constitute the basic set of tags needed to create
|
|
HTML documents.
|
|
HTML elements that conform to Level 1, but are not in Level
|
|
0, may not necessarily be implemented in the same manner in every
|
|
browser.
|
|
HTML elements which conform to Level 2, but are not in Level
|
|
1, are the tags that are used to create forms.
|
|
Elements that were to be in the former HTML+ specification
|
|
will most likely be included in a future HTML 3.0 specification.
|
|
The aims of HTML 2.0 are to document valid uses of tags in order
|
|
to provide guidance for authors and software developers and to
|
|
enable the interoperability of HTML documents among a variety of
|
|
Web applications.
|
|
The fact that the process of solidifying the HTML standard
|
|
has been a tumultuous one reflects the participatory nature of
|
|
the Internet and the difficulties of reaching ad hoc consensus
|
|
among a wide range of users. A more formal means for maintaining
|
|
the HTML standard was established in July 1994 under the guidance
|
|
of the Internet Engineering Task Force (IETF), which has
|
|
responsibility for developing and reviewing Internet standards.
|
|
The IETF Working Group on HTML is chaired by Tim Berners-Lee, who
|
|
has been the creative and inspirational force behind the
|
|
World-Wide Web since its inception.
|
|
|
|
+ Page 35 +
|
|
|
|
13.0 Bringing Graphic Design to the Internet
|
|
|
|
Often, Web providers initially create servers to promote
|
|
networked communications to their parent institutions. Tools
|
|
such as NCSA's Mosaic have become excellent PR devices for the
|
|
Internet. The ability to place scanned images and original
|
|
graphics alongside of text can make a strong impression to an
|
|
institution's senior officers. Yet, effectively demonstrating
|
|
that these tools are worthy of an institutional commitment of
|
|
time and funds depends upon a quality presentation.
|
|
Graphical browsers that display images and multiple fonts
|
|
have brought graphical design to the Internet; however, the
|
|
flexibility that HTML allows authors in controlling the
|
|
appearance of their documents is quite limited. Future work on
|
|
the HTML standard will likely address these weaknesses with the
|
|
use of style sheets that allow authors to "specify formatting . .
|
|
. without distorting the logical structure markup." [5] The
|
|
visual impact of a document also involves a significant
|
|
navigational issue or what Jakob Nielsen refers to as the
|
|
"homogeneity problem":
|
|
|
|
The differences in graphical design are intended to reduce
|
|
the homogeneity problem in on-line text, which basically is
|
|
that on-line text always looks the same. . . . On-line text
|
|
does not have the variety which traditional text has, due to
|
|
variations in typefont, book size, color, etc., or even the
|
|
basic differences in physical looks between, say a real
|
|
book, a newspaper, and a note written on a napkin in the
|
|
cafeteria during a lunch break. [6]
|
|
|
|
One HTML example of how the traditional bookcase can be used as a
|
|
means of orienting users to different online documents can be
|
|
found at Novell Online Services (http://www.novell.com/). On its
|
|
home page, Novell has an image of books sitting on a shelf. The
|
|
spine of each "book" has a title that matches each service that
|
|
is accessible through the company's Web server. A caption reads
|
|
"Click on a book to enter the specified area." The image of the
|
|
bookshelf employs the ISMAP attribute of the IMAGE element. Each
|
|
area of the server has a smaller version of the same "bookcase"
|
|
image. The developer of Novell's Web server handled the problem
|
|
of homogeneity by creatively using the graphic design elements of
|
|
HTML. Navigating through this Web server is as easy as "pulling
|
|
a book from the shelf" by clicking on it.
|
|
|
|
+ Page 36 +
|
|
|
|
However, as Nielsen observes:
|
|
|
|
One might argue that homogeneity could be desirable because
|
|
it emphasizes the book metaphor and because readers can
|
|
assimilate information faster when they encounter a familiar
|
|
format. Of course, this is true to some extent but we would
|
|
actually want to avoid the book metaphor in our future
|
|
hypertext designs because it seems to limit the conceptual
|
|
models of the search potential of hypertext and non-linear
|
|
navigation of the information system. [7]
|
|
|
|
For the small information spaces that are often found in
|
|
the Web, the homogeneity problem can be resolved through the use
|
|
of familiar organizational metaphors. For larger information
|
|
spaces, these familiar concepts may not transfer to an electronic
|
|
environment. What may be needed for large collections of
|
|
research material is nothing less than a Copernican revolution in
|
|
the way we look at the written expressions of language. While
|
|
the World-Wide Web itself will not likely produce such a radical
|
|
change, the Web does foster the environment for such thinking.
|
|
|
|
14.0 Library Uses of HTML
|
|
|
|
HTML increases the librarian's ability to deliver value-added
|
|
networked information. Rather than only providing printed
|
|
materials at Internet training sessions, librarians can prepare
|
|
customized HTML documents for each group of users. As new
|
|
Internet sites are discovered and added, these documents can
|
|
become dynamic guides to network resources. Using HTML as the
|
|
medium for a presentation, rather than an overhead transparency
|
|
or presentation software, provides a new degree of training
|
|
versatility. Configuring Web servers so that subject specialists
|
|
and trainers have control over updating their own HTML documents
|
|
lessens the system administrator's burden of maintaining
|
|
documents stored on the server.
|
|
|
|
+ Page 37 +
|
|
|
|
Another training impact could be the delivery of hypertext-
|
|
based instruction using the Web. Previously, this kind of
|
|
instruction has only been available through software such as
|
|
HyperCard and ToolBook. While HTML does not have all the
|
|
advanced features of these packages, it can be used to create
|
|
instructional environments that not only transcend a single
|
|
computer platform, but also extend over the campus network and
|
|
allow students to use the program from locations other than the
|
|
library. Also, as teachers develop their own networked
|
|
instructional multimedia materials, there are opportunities to
|
|
more effectively integrate library resources into the curriculum.
|
|
By actively exploring the possible uses of HTML, a library can
|
|
identify needs that can only be met with networked hypermedia.
|
|
In addition to enabling new training methods, HTML is a
|
|
suitable tool for publishing electronic journals and newsletters.
|
|
While HTML does not scale to fit the complexity of many
|
|
publications, it does provide enough flexibility for the ASCII-
|
|
based electronic journals that are currently in existence. Since
|
|
many articles in these electronic journals already reference
|
|
other electronic materials, the use of hypertext links would
|
|
facilitate the retrieval of related information. Furthermore,
|
|
HTML would allow electronic journals to expand beyond ASCII
|
|
limitations and include photographs and other images. Finally,
|
|
with the movement of electronic journals toward HTML, the
|
|
electronic resources provided by today's libraries might begin to
|
|
more clearly resemble the networked environment of the future.
|
|
Indeed, as Ross Atkinson advises:
|
|
|
|
In considering the future of scholarly information exchange,
|
|
we must therefore take into account not only the facility of
|
|
the network but also the effects of computers on scholarly
|
|
reading and writing. Certainly one of the best approaches
|
|
to such an assessment is to focus on the phenomenon of
|
|
hypertext because it is through the concept (if not yet the
|
|
reality) of hypertext that we begin to sense the most
|
|
fundamental and far-reaching effects of the computer on the
|
|
communications in general and scholarly information exchange
|
|
in particular. [8]
|
|
|
|
+ Page 38 +
|
|
|
|
15.0 Conclusion
|
|
|
|
The Web and HTML bring the reality of hypertext into everyday
|
|
life for many Internet users. As Web browsers become more
|
|
sophisticated and pervasive, HTML raises ASCII text to new levels
|
|
of usability. HTML is becoming a common denominator for
|
|
accessing electronic services in a networked environment.
|
|
Through the use of the enabling technologies found in the
|
|
World-Wide Web, librarians can explore the obstacles and barriers
|
|
that will need to be overcome in implementing future library
|
|
services.
|
|
|
|
|
|
Notes
|
|
|
|
1. T. J. Berners-Lee, R. Cailliau, J. F. Groff, and B.
|
|
Pollerman, "World-Wide Web: An Information Infrastructure for
|
|
High-Energy Physics" (Presented at Software Engineering,
|
|
Artificial Intelligence, and Expert Systems for High Energy and
|
|
Nuclear Physics, La Londe-les-Maures, France, January 1992).
|
|
(Preprint available by anonymous ftp; URL: ftp://info.cern.ch/
|
|
pub/www/doc/www-for-hep.ps.Z.)
|
|
|
|
2. John Price-Wilkin, "Using the World-Wide Web to Deliver
|
|
Complex Electronic Documents: Implications for Libraries," The
|
|
Public-Access Computer Systems Review 5, no. 3 (1994): 5-21. (To
|
|
retrieve this article, send the following e-mail message to
|
|
listserv@uhupvm1.uh.edu: GET PRICEWIL PRV5N3 F=MAIL.)
|
|
|
|
3. The latest edition of the HyperText Markup Language (HTML),
|
|
Version 2.0 specification is available from the following URL:
|
|
http://www.hal.com/~connolly/html-spec.
|
|
|
|
4. James H. Coombs, Allen H. Renear, and Steven J. DeRose,
|
|
"Markup Systems and the Future of Scholarly Text Processing,"
|
|
Communications of the ACM 30 (November 1987): 944.
|
|
|
|
5. Charles F. Goldfarb, The SGML Handbook (Oxford: Clarendon
|
|
Press, 1990), 93.
|
|
|
|
6. Jakob Nielsen, "The Art of Navigating Through Hypertext,"
|
|
Communications of the ACM 33 (March 1990): 299.
|
|
|
|
7. Ibid., 300.
|
|
|
|
8. Ross Atkinson, "Networks, Hypertext, and Academic Information
|
|
Services: Some Longer-Range Implications," College & Research
|
|
Libraries 54 (May 1993): 202.
|
|
|
|
+ Page 39 +
|
|
|
|
Appendix A. HTML Tags
|
|
|
|
In the following entries, the level description is for HTML 2.0.
|
|
|
|
1.0 ADDRESS
|
|
|
|
Tag: <ADDRESS></ADDRESS>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Used to provide authorship information for HTML documents.
|
|
Normally found at the bottom of documents.
|
|
|
|
Optional Attributes:
|
|
|
|
None.
|
|
|
|
Comments:
|
|
|
|
ADDRESS is a very useful tag that enables users to quickly
|
|
identify a document's author. The ADDRESS tag may contain a link
|
|
to another HTML document that provides additional information
|
|
about the author. The text of this tag typically appears in
|
|
italics when displayed.
|
|
|
|
Example:
|
|
|
|
<ADDRESS>Jeff Barry jeff@utkux.utcc.utk.edu</ADDRESS>
|
|
|
|
2.0 ANCHOR
|
|
|
|
Tag: <A></A>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The start and end ANCHOR tags surround text that represents a
|
|
hypertext link. When used with the HREF attribute, the ANCHOR
|
|
tag represents the origin of a link. When used with the NAME
|
|
attribute, the ANCHOR tag serves as the destination of a link.
|
|
|
|
+ Page 40 +
|
|
|
|
Attributes:
|
|
|
|
HREF Specifies, in the form of a URL, the document to be
|
|
retrieved when the link is selected.
|
|
|
|
NAME Identifies the text as a specific location within the
|
|
document. It can be the destination of a hypertext
|
|
link.
|
|
|
|
Level 1 Attributes:
|
|
|
|
TITLE The value for this attribute is the title of the
|
|
document given by the URL in the HREF attribute.
|
|
|
|
URN Specifies the Uniform Resource Number (URN) for the
|
|
document given by the URL in the HREF attribute.
|
|
|
|
METHODS Specifies functions for the document given by the URL
|
|
in the HREF attribute. Prior to link activation,
|
|
METHOD indicates to the user whether the linked
|
|
document is searchable, is an image, or has some other
|
|
special function. Depending on the method indicated,
|
|
links may be displayed differently. Not all Web
|
|
browsers support this attribute.
|
|
|
|
Proposed Attributes:
|
|
|
|
REL Provides the relationship between the originating
|
|
document and the destination document.
|
|
|
|
REV Provides the relationship between the destination
|
|
document and the originating document.
|
|
|
|
Comments:
|
|
|
|
For the ANCHOR tag to be functional, one of the attributes HREF
|
|
or NAME must be used, or both of these attributes must be used.
|
|
The Level 1 and proposed attributes serve advanced uses of HTML
|
|
and are by no means required.
|
|
|
|
Example:
|
|
|
|
<A HREF="http://sunsite.unc.edu/expo/ticket_office.html">EXPO, a
|
|
showcase of online exhibits</A>
|
|
|
|
+ Page 41 +
|
|
|
|
3.0 BASE
|
|
|
|
Tag: <BASE>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Records the URL of the document for use by partial URLs, which
|
|
will be relative to this base URL.
|
|
|
|
Required Attribute:
|
|
|
|
HREF Specifies the URL of the document.
|
|
|
|
Comments:
|
|
|
|
The BASE element is only used in the HEAD of an HTML document.
|
|
When BASE is not present, relative URLs are resolved against the
|
|
URL used to access the document. Use of the BASE element is not
|
|
required. The BASE element does not have an end tag.
|
|
|
|
Example:
|
|
|
|
<BASE HREF="http://sunsite.unc.edu/expo/deadsea.scrolls/
|
|
Intro.html">
|
|
|
|
4.0 BLOCKQUOTE
|
|
|
|
Tag: <BLOCKQUOTE></BLOCKQUOTE>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Renders enclosed text in a distinguishing manner to indicate a
|
|
quotation.
|
|
|
|
Optional Attributes:
|
|
|
|
None.
|
|
|
|
Comments:
|
|
|
|
Specific rendering depends upon the browser, but the text is
|
|
usually either in italics or with left and right margins
|
|
indented.
|
|
|
|
+ Page 42 +
|
|
|
|
Example:
|
|
|
|
<BLOCKQUOTE>If a man does not keep pace with his companions,
|
|
perhaps it is because he hears a different drummer. Let him step
|
|
to the music which he hears, however measured or far
|
|
away.</BLOCKQUOTE>
|
|
|
|
5.0 BODY
|
|
|
|
Tag: <BODY></BODY>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The BODY element represents one of the two main hierarchical
|
|
divisions of an HTML document (the other division being the
|
|
HEAD). Essentially, the BODY is the text that is to be
|
|
displayed.
|
|
|
|
Comments:
|
|
|
|
The BODY can include the following elements and types of
|
|
elements: ADDRESS, ANCHOR, BLOCKQUOTE, FORM, Heading elements
|
|
(e.g., HEADING 1), Highlighting elements (e.g., <B>, <I>, <EM>,
|
|
and <STRONG>), HORIZONTAL RULE, IMG, LINE BREAK, List elements
|
|
(e.g., ORDERED LIST), PARAGRAPH, PREFORMATTED TEXT, and special
|
|
characters.
|
|
|
|
Example:
|
|
|
|
<BODY>
|
|
Your <EM>home page</EM> may include links to other information
|
|
sources on the network, information about yourself, and even your
|
|
photograph.
|
|
</BODY>
|
|
|
|
6.0 BOLD
|
|
|
|
Tag: <B></B>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates that enclosed text should be highlighted using a bold
|
|
font style.
|
|
|
|
Optional Attributes:
|
|
|
|
None.
|
|
|
|
+ Page 43 +
|
|
|
|
Comments:
|
|
|
|
The BOLD element is a physical tag that only provides formatting
|
|
information. Preferably, use either the <EM> or <STRONG> tags to
|
|
denote emphasis or strong emphasis.
|
|
|
|
Example:
|
|
|
|
HTML provides the flexibility of crafting a <B>toolbox of
|
|
networked resources</B> that meets your needs.
|
|
|
|
7.0 CITE
|
|
|
|
Tag: <CITE></CITE>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Renders the enclosed text in a distinguishing style to indicate a
|
|
citation.
|
|
|
|
Comments:
|
|
|
|
Usually displayed in italics.
|
|
|
|
Example:
|
|
|
|
<CITE>Henry David Thoreau. Walden, 1854.</CITE>
|
|
|
|
8.0 CODE
|
|
|
|
Tag: <CODE></CODE>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
A highlighting feature that renders the enclosed text in a
|
|
distinguishing style to indicate a sample of computer code.
|
|
|
|
Comments:
|
|
|
|
Usually displayed in a monospace font.
|
|
|
|
+ Page 44 +
|
|
|
|
Example:
|
|
|
|
<CODE>
|
|
#!/usr/bin/perl
|
|
print "This is a sample of computer code.\n";
|
|
</CODE>
|
|
|
|
9.0 DEFINITION "DEFINED"
|
|
|
|
Tag: <DD>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that the designated text is a term definition that is
|
|
in a definition list.
|
|
|
|
Comments:
|
|
|
|
Must follow the content of a <DT> tag. Can only be used within a
|
|
DEFINITION LIST (<DL>). Use of a </DD> end tag is optional.
|
|
|
|
Example:
|
|
|
|
<DL>
|
|
<DT>NCSA<DD>The National Center for Supercomputing Applications
|
|
created the Mosaic browser, which was instrumental in bringing
|
|
greater attention to the World-Wide Web.
|
|
</DL>
|
|
|
|
10.0 DEFINITION LIST
|
|
|
|
Tag: <DL></DL>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Formats terms like a glossary.
|
|
|
|
Optional Attribute:
|
|
|
|
COMPACT Reduces the amount of white space between terms. Used
|
|
as <DL COMPACT>. This attribute has no value.
|
|
|
|
+ Page 45 +
|
|
|
|
Comments:
|
|
|
|
Must be used with the <DT> and <DD> tags to indicate the term to
|
|
be defined and the definition of that term. Terms are listed in
|
|
the left column, with the definitions in the right column. Long
|
|
definitions will wrap to succeeding lines. The <DL> tag must be
|
|
followed immediately by the <DT> tag.
|
|
|
|
Example:
|
|
|
|
<DL>
|
|
<DT>URL<DD>Uniform Resource Locator is the standard used to refer
|
|
to documents and their locations on the Internet.
|
|
</DL>
|
|
|
|
11.0 DEFINITION TERM
|
|
|
|
Tag: <DT>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that designated text is a term to be defined in a
|
|
DEFINITION LIST.
|
|
|
|
Comments:
|
|
|
|
A <DT> is followed by the term, which is then followed by a <DD>
|
|
tag to indicate the actual definition of the term. The defined
|
|
term is usually displayed along the left margin. Use of a </DT>
|
|
end tag is optional.
|
|
|
|
Example:
|
|
|
|
<DL>
|
|
<DT>WWW<DD>The World-Wide Web, originating out of CERN in
|
|
Switzerland, provides hypertext on the Internet through the use
|
|
of HTTP and HTML.
|
|
</DL>
|
|
|
|
+ Page 46 +
|
|
|
|
12.0 DIRECTORY LIST
|
|
|
|
Tag: <DIR></DIR>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
A listing feature that displays short items (20 characters or
|
|
less) in columns.
|
|
|
|
Comments:
|
|
|
|
Used in conjunction with the <LI> tags to designate the items in
|
|
each column. Depending upon its interpretation by browsers and
|
|
the length of listed items, the DIRECTORY LIST may yield
|
|
unexpected results. This element is seldom used.
|
|
|
|
Example:
|
|
|
|
<DIR>
|
|
<LI>first column<LI>second column
|
|
</DIR>
|
|
|
|
13.0 EMPHASIS
|
|
|
|
Tag: <EM></EM>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
The enclosed text will be highlighted.
|
|
|
|
Comments:
|
|
|
|
The appearance of text surrounded with the <EM></EM> tags is
|
|
determined by the Web browser. However, the text is normally
|
|
displayed in italics.
|
|
|
|
Example:
|
|
|
|
Your <EM>home page</EM> may include links to other information
|
|
sources on the network, information about yourself, and even your
|
|
photograph.
|
|
|
|
+ Page 47 +
|
|
|
|
14.0 FORM
|
|
|
|
Tag: <FORM></FORM>
|
|
|
|
Level: 2
|
|
|
|
Function:
|
|
|
|
Indicates that a form is included within an HTML document.
|
|
|
|
Comments:
|
|
|
|
All Web browsers do not support the FORM tag.
|
|
|
|
15.0 HEADER
|
|
|
|
Tag: <HEAD></HEAD>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Contains information describing the HTML document.
|
|
|
|
Comments:
|
|
|
|
Elements contained in the HEADER of an HTML document are not
|
|
displayed by a browser with the document. Use of a HEADER is
|
|
recommended, but not required. The following tags are allowed
|
|
within the <HEAD> tag: BASE, ISINDEX, LINK, NEXTID, TITLE.
|
|
|
|
Example:
|
|
|
|
<HEAD>
|
|
<TITLE>Sample Home Page</TITLE>
|
|
</HEAD>
|
|
|
|
16.0 HEADING 1
|
|
|
|
Tag: <H1></H1>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The first level heading, represented in a very large bold font
|
|
and centered.
|
|
|
|
+ Page 48 +
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
Example:
|
|
|
|
<H1>The most prominent text displayed in a document</H1>
|
|
|
|
17.0 HEADING 2
|
|
|
|
Tag: <H2></H2>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The second level heading, represented in a large, bold font with
|
|
no indentation.
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
Example:
|
|
|
|
<H2>Text describing the second level of a document</H2>
|
|
|
|
18.0 HEADING 3
|
|
|
|
Tag: <H3></H3>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The third level heading, represented in a large italic font that
|
|
is slightly indented.
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
+ Page 49 +
|
|
|
|
Example:
|
|
|
|
<H3>Text describing the third level of a document</H3>
|
|
|
|
19.0 HEADING 4
|
|
|
|
Tag: <H4></H4>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The fourth level heading, represented in a bold normal font and
|
|
indented.
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
Example:
|
|
|
|
<H4>Text describing the fourth level of a document</H4>
|
|
|
|
20.0 HEADING 5
|
|
|
|
Tag: <H5></H5>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The fifth level heading, represented in a normal italic font and
|
|
indented.
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
Example:
|
|
|
|
<H5>Text describing the fifth level of a document</H5>
|
|
|
|
+ Page 50 +
|
|
|
|
21.0 HEADING 6
|
|
|
|
Tag: <H6></H6>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The sixth level heading, represented in a normal bold font and
|
|
indented.
|
|
|
|
Comments:
|
|
|
|
The Web browser determines font representation, although the
|
|
above rendering is recommended by the HTML specifications. Do
|
|
not use the PARAGRAPH tag (<P>) within or around headings.
|
|
|
|
Example:
|
|
|
|
<H6>Text describing the sixth level of a document</H6>
|
|
|
|
22.0 HORIZONTAL RULE
|
|
|
|
Tag: <HR>
|
|
|
|
Level: Level 0
|
|
|
|
Function:
|
|
|
|
Indicates to a Web browser that a horizontal divider line should
|
|
be displayed at the designated location within the HTML document.
|
|
|
|
Comments:
|
|
|
|
No end tag required.
|
|
|
|
Example:
|
|
|
|
<P>Additional information about the <A
|
|
HREF="http://info.cern.ch/hypertext/WWW/TheProject.html">World-
|
|
Wide Web Project</A> is available for those interested in
|
|
learning more about networked hypermedia.
|
|
<HR>
|
|
|
|
<H2>Example of Using Relative URLs</H2>
|
|
|
|
+ Page 51 +
|
|
|
|
23.0 HTML Label
|
|
|
|
Tag: <HTML></HTML>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Labels the file as being an HTML document.
|
|
|
|
Comments:
|
|
|
|
The <HTML> tag comes at the beginning of an HTML document and the
|
|
</HTML> tag comes at the end. Use of this element is
|
|
recommended, but not required.
|
|
|
|
24.0 IMG
|
|
|
|
Tag: <IMG>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates that an image is to be included in the HTML document
|
|
|
|
Comments:
|
|
|
|
No end tag required.
|
|
|
|
Mandatory Attribute:
|
|
|
|
SRC Identifies the source of the image file using URL
|
|
syntax.
|
|
|
|
Optional Attributes:
|
|
|
|
ALIGN Indicates whether text should be aligned with the top,
|
|
middle, or bottom of the image. Valid values: top,
|
|
middle, bottom.
|
|
|
|
ALT Specifies the text that should be displayed by Web
|
|
browsers that do not support images.
|
|
|
|
ISMAP Indicates that the image is a graphical map that has
|
|
"hot spots" corresponding to hypertext links.
|
|
|
|
Example:
|
|
|
|
<IMG SRC="machu_p.gif" ALT="Ruins at Machu Pitthu, Peru">
|
|
|
|
+ Page 52 +
|
|
|
|
25.0 ISINDEX
|
|
|
|
Tag: <ISINDEX>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
The inclusion of this tag indicates that the HTML document is
|
|
searchable, provided that the Web server supports this
|
|
capability.
|
|
|
|
Comments:
|
|
|
|
No end tag required.
|
|
|
|
26.0 ITALICS
|
|
|
|
Tag: <I></I>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
These tags indicate that the enclosed text is to be displayed in
|
|
an italics font.
|
|
|
|
Comments:
|
|
|
|
The <I> tag represents a formatting instruction to Web browsers.
|
|
It is recommended that an <EM> tag be used rather than the <I>
|
|
tag to indicate emphasis.
|
|
|
|
Example:
|
|
|
|
Your <I>home page</I> may include links to other information
|
|
sources on the network, information about yourself, and even your
|
|
photograph.
|
|
|
|
27.0 KEYBOARD SAMPLE
|
|
|
|
Tag: <KBD></KBD>
|
|
|
|
Level: 1
|
|
|
|
+ Page 53 +
|
|
|
|
Function:
|
|
|
|
Indicates that the enclosed text is a sample of a keyboard entry
|
|
that should be highlighted.
|
|
|
|
Example:
|
|
|
|
To search the online catalog for a book by its title, type
|
|
<KBD>til</KBD> and press the Enter key.
|
|
|
|
28.0 LINE BREAK
|
|
|
|
Tag: <BR>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that a new line is to be started instead of automatic
|
|
line wrap.
|
|
|
|
Comments:
|
|
|
|
Used to simulate single line spacing when additional white space
|
|
is not desired. Use of a </BR> end tag is optional.
|
|
|
|
Example:
|
|
|
|
<P>Jeff Barry<BR>
|
|
Cooperative Information Services Librarian<BR>
|
|
The University of Tennessee Libraries<BR>
|
|
Knoxville, Tennessee<BR>
|
|
|
|
29.0 LINK
|
|
|
|
Tag: <LINK>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates a relationship between the HTML document and another
|
|
document.
|
|
|
|
Comments:
|
|
|
|
Used only within the HEADER of an HTML document. The LINK
|
|
element is not widely used at the present. Use of a </LINK> end
|
|
tag is optional.
|
|
|
|
+ Page 54 +
|
|
|
|
30.0 LIST ITEM
|
|
|
|
Tag: <LI>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that the designated text represents an item in a list.
|
|
|
|
Comments:
|
|
|
|
The <LI> tag is used as the item indicator with the following
|
|
type of lists: DIRECTORY LIST (<DIR>), MENU LIST (<MENU>),
|
|
ORDERED LIST (<OL>), and UNORDERED LIST (<UL>). The <LI> tag has
|
|
no attributes. Use of a </LI> end tag is optional.
|
|
|
|
Example:
|
|
|
|
<UL>
|
|
<LI> Visit the <A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage</A> Exhibit by the Library of Congress to learn
|
|
about the early exploration of the Western Hemisphere.
|
|
|
|
<LI> Biodiversity and environmental issues in the Appalachians
|
|
are the themes of the <A
|
|
HREF="gopher://www.lib.utk.edu/11/Information-by-
|
|
Subject/S%3a/smokies">Smoky Mountain Database</A>.
|
|
</UL>
|
|
|
|
31.0 MENU LIST
|
|
|
|
Tag: <MENU></MENU>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
This tag is used for a list that contains a small number of
|
|
items.
|
|
|
|
Comments:
|
|
|
|
Items in a MENU LIST are often hypertext links to other
|
|
documents. Like a Gopher menu, each item is usually on a single
|
|
line.
|
|
|
|
+ Page 55 +
|
|
|
|
Example:
|
|
|
|
<MENU>
|
|
<LI><A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage Exhibit</A>
|
|
<LI><A HREF="gopher://www.lib.utk.edu/11/Information-by-
|
|
Subject/S%3a/smokies">Smoky Mountain Database</A>
|
|
</MENU>
|
|
|
|
32.0 NEXTID
|
|
|
|
Tag: <NEXTID>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
A tag provided by HTML editors as a unique identifier for ANCHOR
|
|
tags. Used in the HEAD of an HTML document.
|
|
|
|
Comments:
|
|
|
|
This tag is almost never used by authors manually composing HTML
|
|
documents. All Web browsers do not support this tag. Most users
|
|
will not encounter this tag.
|
|
|
|
33.0 ORDERED LIST
|
|
|
|
Tag: <OL></OL>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Used for a list that contains items in a designated order.
|
|
|
|
Comments:
|
|
|
|
Items in an ORDERED LIST are automatically numbered when
|
|
displayed in a Web browser.
|
|
|
|
Example:
|
|
|
|
<OL>
|
|
<LI>Identify destination of links.
|
|
<LI>Determine text to be anchored as the start of a link.
|
|
</OL>
|
|
|
|
+ Page 56 +
|
|
|
|
34.0 PARAGRAPH
|
|
|
|
Tag: <P></P>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that a block of text forms a paragraph.
|
|
|
|
Comments:
|
|
|
|
Formerly used in HTML to separate paragraphs from each other and
|
|
from other text elements. The PARAGRAPH element in HTML is now a
|
|
container rather than a separator, and the <P> tag should come at
|
|
the beginning of a paragraph. The end tag (</P>) is optional.
|
|
|
|
Example:
|
|
|
|
<P>The text of the first paragraph of your document is entered
|
|
here.
|
|
|
|
35.0 PREFORMATTED TEXT
|
|
|
|
Tag: <PRE></PRE>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Indicates that the formatting of enclosed text should be
|
|
preserved and displayed in a standard monospace font.
|
|
|
|
Example:
|
|
|
|
<PRE>
|
|
$275.43 $128.65 $345.89 $234.96 $674.12
|
|
</PRE>
|
|
|
|
36.0 SAMPLE
|
|
|
|
Tag: <SAMP></SAMP>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Used to indicate a sequence of literal characters.
|
|
|
|
+ Page 57 +
|
|
|
|
Example:
|
|
|
|
The PROLOGUE of an HTML document must be exactly as follows:
|
|
<SAMPLE><!doctype html public "-//W30//DTD W3 HTML 2.0
|
|
//EN"></SAMPLE>
|
|
|
|
37.0 STRONG
|
|
|
|
Tag: <STRONG></STRONG>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates that the enclosed text is a statement with strong
|
|
emphasis that should be displayed in an appropriate font.
|
|
|
|
Comments:
|
|
|
|
Normally displayed in a normal bold font. Should be used rather
|
|
than the physical tag <B> to indicate strong emphasis.
|
|
|
|
Example:
|
|
|
|
HTML provides the flexibility of crafting a <STRONG>toolbox of
|
|
networked resources</STRONG> that meets your needs.
|
|
|
|
38.0 TITLE
|
|
|
|
Tag: <TITLE></TITLE>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Contains the title of the HTML document.
|
|
|
|
Comments:
|
|
|
|
Used only within the HEAD of an HTML document.
|
|
|
|
Example:
|
|
|
|
<TITLE>Sample Home Page</TITLE>
|
|
|
|
+ Page 58 +
|
|
|
|
39.0 TYPEWRITER TYPE
|
|
|
|
Tag: <TT></TT>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates that the enclosed text should be displayed in a
|
|
monospace typewriter font.
|
|
|
|
Comments:
|
|
|
|
Not to be confused with the PREFORMATTED TEXT tag (<PRE>). Use
|
|
<TT> only to highlight a limited number of characters and not a
|
|
block of text.
|
|
|
|
Example:
|
|
|
|
The stock number for the catalog is <TT>S/N 030-000-00238-5</TT>.
|
|
|
|
40.0 UNORDERED LIST
|
|
|
|
Tag: <UL></UL>
|
|
|
|
Level: 0
|
|
|
|
Function:
|
|
|
|
Displays items in no particular order.
|
|
|
|
Comments:
|
|
|
|
Each item in an UNORDERED LIST is specified through use of the
|
|
<LI> tag. When displayed in a Web browser, the <LI> tag is
|
|
replaced by a bullet or some other marking.
|
|
|
|
Example:
|
|
|
|
<UL>
|
|
<LI> Visit the <A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage</A> Exhibit by the Library of Congress to learn
|
|
about the early exploration of the Western Hemisphere.
|
|
|
|
<LI> Biodiversity and environmental issues in the Appalachians
|
|
are the themes of the <A
|
|
HREF="gopher://www.lib.utk.edu/11/Information-by-
|
|
Subject/S%3a/smokies">Smoky Mountain Database</A>.
|
|
</UL>
|
|
|
|
+ Page 59 +
|
|
|
|
41.0 VARIABLE
|
|
|
|
Tag: <VAR></VAR>
|
|
|
|
Level: 1
|
|
|
|
Function:
|
|
|
|
Indicates that enclosed text is the name of a variable.
|
|
|
|
Comments:
|
|
|
|
A logical highlighting element.
|
|
|
|
Example:
|
|
|
|
The do while loop will execute as long as the value of
|
|
<VAR>counter</VAR> is less than or equal to 100.
|
|
|
|
|
|
Appendix B. Sample HTML Document
|
|
|
|
<!doctype html public "-//W30//DTD W3 HTML 2.0//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<TITLE>Sample Home Page</TITLE>
|
|
</HEAD>
|
|
<BODY>
|
|
<H1>Jeff's Home on the Net</H1>
|
|
|
|
Your <EM>home page</EM> may include links to other information
|
|
sources on the network, information about yourself, and even your
|
|
photograph. HTML provides the flexibility of crafting a
|
|
<STRONG>toolbox of networked resources</STRONG> that meets your
|
|
needs.
|
|
|
|
<P>Additional information about the <A
|
|
HREF="http://info.cern.ch/hypertext/WWW/TheProject.html">World-
|
|
Wide Web Project</A> is available for those interested in
|
|
learning more about networked hypermedia.
|
|
<HR>
|
|
|
|
+ Page 60 +
|
|
|
|
<H2>Example of Using Relative URLs</H2>
|
|
|
|
More information about creating documents for the Web can be
|
|
found in <A HREF="htmlguides.html">Guides to HTML</A>. To
|
|
facilitate the authoring of HTML documents a number of <A
|
|
HREF="tools/editors.html">HTML editors</A> are being developed.
|
|
<A HREF="../lbryfiles/userguide.html">Ways of Using Networked
|
|
Resources</A> in the library is another document for learning to
|
|
use the Internet.
|
|
|
|
<H2>Examples of Using Lists in HTML</H2>
|
|
|
|
<H3>An Unordered List of Internet Resources</H3>
|
|
|
|
<UL>
|
|
<LI> Visit the <A
|
|
HREF="http://sunsite.unc.edu/expo/1492.exhibit/Intro.html">1492:
|
|
An Ongoing Voyage</A> Exhibit by the Library of Congress to learn
|
|
about the early exploration of the Western Hemisphere.
|
|
|
|
<LI> Biodiversity and environmental issues in the Appalachians
|
|
are the themes of the <AHREF="gopher://www.lib.utk.edu/
|
|
11/Information-by-Subject/S%3a/smokies">Smoky Mountain
|
|
Database</A>.
|
|
|
|
<LI>The <A HREF="telnet://database.carl.org/">CARL
|
|
Corporation</A> provides an excellent interactive service
|
|
accessible over the Internet.
|
|
|
|
<LI> The proceedings <A HREF="ftp://ftp.cni.org/pub/LITA/tiip-
|
|
forum/proceedings.html">Principles for the Development of the
|
|
National Information Infrastructure</A> from ALA's
|
|
Telecommunications and Information Infrastructure Policy Forum
|
|
are available on the Internet.
|
|
</UL>
|
|
|
|
<H3>Creating Hypertext Links in HTML</H3>
|
|
|
|
<OL>
|
|
<LI>Identify the destination of links.
|
|
<LI>Determine text to be anchored as the start of a link.
|
|
<LI>Surround text with anchor tags.
|
|
<LI>Insert within the starting anchor tag the URL of the link's
|
|
destination as the value of the HREF attribute.
|
|
<LI>Use the NAME attribute so that the anchored text may also be
|
|
the destination of a link.
|
|
<LI>Be sure to close the anchor with the end tag.
|
|
<LI>Test the link in a browser.
|
|
</OL>
|
|
|
|
+ Page 61 +
|
|
|
|
<H3>Glossary of Selected Acronyms</H3>
|
|
|
|
<DL>
|
|
<DT>URL<DD>Uniform Resource Locator is the standard used to refer
|
|
to documents and their locations on the Internet.
|
|
|
|
<DT>NCSA<DD>The National Center for Supercomputing Applications
|
|
created the Mosaic browser, which was instrumental in bringing
|
|
greater attention to the World-Wide Web.
|
|
|
|
<DT>WWW<DD>The World-Wide Web, originating out of CERN in
|
|
Switzerland, provides hypertext on the Internet through the use
|
|
of HTTP and HTML.
|
|
|
|
<DT>SGML<DD>The Standard Generalized Markup Language is an
|
|
international standard that describes the structure of a
|
|
document.
|
|
|
|
<DT>DTD<DD>A Document Type Definition, specified according to the
|
|
rules of SGML (e.g., HTML), describes a document's
|
|
structure for the purposes of a particular application such as
|
|
Web.
|
|
|
|
<DT>CERN<DD>The Swiss organization that started the World-Wide
|
|
Wed initiative. The words of the acronym translate into English
|
|
as the European Laboratory for Particle Physics.
|
|
</DL>
|
|
|
|
<ADDRESS>Jeff Barry jeff@utkux.utcc.utk.edu</ADDRESS>
|
|
</BODY>
|
|
</HTML>
|
|
|
|
Appendix C. Sources of Information About HTML and the Web
|
|
|
|
More information about the following topics can be found at the
|
|
indicated URLs:
|
|
|
|
o HTTP
|
|
|
|
http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html
|
|
|
|
o World-Wide Web Initiative
|
|
|
|
http://info.cern.ch/hypertext/WWW/TheProject.html
|
|
|
|
o Web-related mailing lists.
|
|
|
|
http://info.cern.ch/hypertext/WWW/Administration/
|
|
Mailing/Overview.html
|
|
|
|
+ Page 62 +
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|
|
|
Other useful sources of information include:
|
|
|
|
o A list server, web4lib@library.berkeley.edu, about the
|
|
delivery of library services via the Web (to subscribe,
|
|
send an e-mail message to listserv@library.berkeley.edu
|
|
that says "sub web4lib your first name your last
|
|
name").
|
|
|
|
o The World-Wide Web FAQ (Frequently Asked Questions),
|
|
which is maintained by Thomas Boutell. the FAQ is
|
|
posted to the comp.infosystems.www newsgroups and is
|
|
available by anonymous FTP from rtfm.mit.edu in the
|
|
directory /pub/usenet/news.answers/www/faq.
|
|
|
|
|
|
About the Author
|
|
|
|
Jeff Barry, Cooperative Information Services Librarian, The
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University of Tennessee Libraries, Knoxville, TN 37996.
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|
Internet: jeff@utkux.utcc.utk.edu.
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|
|
|
-----------------------------------------------------------------
|
|
The Public-Access Computer Systems Review is an electronic
|
|
journal that is distributed on the Internet and on other computer
|
|
networks. There is no subscription fee.
|
|
To subscribe, send an e-mail message to
|
|
listserv@uhupvm1.uh.edu that says: SUBSCRIBE PACS-P First Name
|
|
Last Name.
|
|
This article is Copyright (C) 1994 by Jeff Barry. All
|
|
Rights Reserved.
|
|
The Public-Access Computer Systems Review is Copyright (C)
|
|
1994 by the University Libraries, University of Houston. All
|
|
Rights Reserved.
|
|
Copying is permitted for noncommercial use by academic
|
|
computer centers, computer conferences, individual scholars, and
|
|
libraries. Libraries are authorized to add the journal to their
|
|
collection, in electronic or printed form, at no charge. This
|
|
message must appear on all copied material. All commercial use
|
|
requires permission.
|
|
-----------------------------------------------------------------
|
|
|
|
+ Page 63 +
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|
-----------------------------------------------------------------
|
|
Public-Access Provocations: An Informal Column
|
|
-----------------------------------------------------------------
|
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|
|
-----------------------------------------------------------------
|
|
Crawford, Walt. "And Only Half of What You See, Part II:
|
|
Skeletons in the Catalog." The Public-Access Computer Systems
|
|
Review 5, no. 5 (1994): 63-66. To retrieve this file, send the
|
|
following e-mail message to listserv@uhupvm1.uh.edu: GET CRAWFORD
|
|
PRV5N5 F=MAIL. (The file is also available from the University
|
|
of Houston Libraries' Gopher server: info.lib.uh.edu, port 70.)
|
|
-----------------------------------------------------------------
|
|
|
|
Last year, the "Worst Serial Title Change Awards" report included
|
|
an item scolding Ziff-Davis Publishing for abruptly changing the
|
|
volume numbering on Popular Photography. [1] After all,
|
|
Ziff-Davis, with some of the most popular and longest established
|
|
special-interest magazines, should know better.
|
|
Just one problem with the item: Ziff-Davis doesn't publish
|
|
Popular Photography and hasn't for several years. Ziff-Davis
|
|
also doesn't publish Stereo Review or several other popular
|
|
special-interest magazines that it used to. The current
|
|
publisher for both magazines mentioned is Hachette Filipacchi
|
|
Magazines, Inc. But then, Ziff-Davis didn't sell the magazines
|
|
to Hachette; Ziff-Davis sold them to CBS Magazines, which in turn
|
|
sold them to Hachette.
|
|
This all happened in the 1980s, when Ziff-Davis chose to
|
|
focus its publishing efforts on its growing stable of computer
|
|
magazines and other computer-related information.
|
|
|
|
Source of the Confusion?
|
|
|
|
What happened here? I can't be sure, but here's a good guess.
|
|
The committee members did just what you or I would probably do to
|
|
check a publisher's name: they went to the catalog--either a
|
|
local online catalog, OCLC, or RLIN. And they found Ziff-Davis
|
|
as the publisher for Popular Photography because technical
|
|
processing departments and CONSER participants don't update
|
|
catalog records for a serial when such a trivial detail as the
|
|
publisher's name changes.
|
|
Oh, the CONSER record's been changed, partly to note the
|
|
change in volume numbering (which catalogers do care about). Now
|
|
it has "CBS Magazines etc." as publisher and "Los Angeles etc."
|
|
as place, where only the "etc." parts are currently correct.
|
|
I'm not saying this practice is wrong, but it does mean that
|
|
online catalogs are essentially worthless as sources for
|
|
publisher information on serials. Do most patrons know that?
|
|
Well, if serials librarians forget it, how likely is it that the
|
|
patrons are warned?
|
|
|
|
+ Page 64 +
|
|
|
|
Everything Is Checked Unless It Isn't
|
|
|
|
What can patrons trust in the online catalog? Librarians take
|
|
considerable (and generally justifiable) pride in authority
|
|
control, assuring not only that information is correct, but that
|
|
it's checked and normalized. The catalog database is part of
|
|
what makes a library more than just a big heap of books; it must
|
|
be right.
|
|
There are two gotchas to that assumption. First, "right"
|
|
for authority-controlled information means the normalized form,
|
|
not necessarily the form as it appears on the item. That may not
|
|
be a major factor most of the time, although some patrons may be
|
|
puzzled that the author they see atop the catalog record isn't
|
|
what they see on the book cover.
|
|
The more important factor: what gets checked, and what gets
|
|
changed from copy cataloging sources (including
|
|
cataloging-in-publication records), is only what the library
|
|
regards as significant. Form of name is significant. Pagination
|
|
probably isn't. Publisher's name and address don't always seem
|
|
to be. I know there are catalog records for my book Patron
|
|
Access: Issues for Online Catalogs that show the publisher as
|
|
Knowledge Industry Publications, rather than G.K. Hall, because
|
|
the cataloging-in-publication record was created before KIPI sold
|
|
the series to Hall, although Hall actually published the book.
|
|
No cataloger ever saw an actual physical book with that title and
|
|
Knowledge Industry as the publisher; that's irrelevant. (I
|
|
should note that most records have the correct publisher.)
|
|
|
|
Who Really Cares?
|
|
|
|
None of this constitutes a library emergency. Experienced
|
|
librarians have some sense of which information in catalog
|
|
records can be trusted and which should be used with care. Do
|
|
patrons? Probably not.
|
|
Should they? Yes, if missing or inaccurate data will affect
|
|
them. Users need to know when skepticism is warranted--when they
|
|
should assume that the computer catalog may be telling them lies.
|
|
|
|
+ Page 65 +
|
|
|
|
Sins of Omission
|
|
|
|
A much greater problem than bad data in the catalog is missing
|
|
data. A close friend who runs a small college library with half
|
|
a dozen CD-ROM periodical indexes and a CD-ROM catalog (with full
|
|
recon) sometimes despairs because students needing quick topical
|
|
information just go for the periodical indexes. My friend knows
|
|
that the students would frequently get better (more useful, more
|
|
thoughtful, better organized, and more balanced) background from
|
|
a chapter in a book--but they don't have ready access to those
|
|
chapters. These sins of omission would be costly to rectify.
|
|
And although this problem has been known for many years, solving
|
|
it doesn't seem sexy, particularly to those who regard books as
|
|
passe in any case. It's tough enough just to complete
|
|
retrospective conversion (and I still believe it's more important
|
|
to get everything into the catalog first, then move on to
|
|
providing greater depth of access).
|
|
Balance? Thoughtfulness? Not nearly as important as
|
|
timeliness. What's new is best, even if it's shallow or
|
|
incorrect, or far too specialized for the user's needs.
|
|
But that's another topic for another day.
|
|
|
|
|
|
Notes
|
|
|
|
1. Rosanna M. O'Neil, "Worst Serial Title Change Awards," ALCTS
|
|
Newsletter 4, nos. 6-7 (1993): 80.
|
|
|
|
|
|
About the Author
|
|
|
|
Walt Crawford, Senior Analyst, The Research Libraries Group,
|
|
Inc., 1200 Villa Street, Mountain View, CA 94041-1100. Internet:
|
|
br.wcc@rlg.stanford.edu.
|
|
|
|
+ Page 66 +
|
|
|
|
-----------------------------------------------------------------
|
|
The Public-Access Computer Systems Review is an electronic
|
|
journal that is distributed on the Internet and on other computer
|
|
networks. There is no subscription fee.
|
|
To subscribe, send an e-mail message to
|
|
listserv@uhupvm1.uh.edu that says: SUBSCRIBE PACS-P First Name
|
|
Last Name.
|
|
This article is Copyright (C) 1994 by Walt Crawford. All
|
|
Rights Reserved.
|
|
The Public-Access Computer Systems Review is Copyright (C)
|
|
1994 by the University Libraries, University of Houston. All
|
|
Rights Reserved.
|
|
Copying is permitted for noncommercial use by academic
|
|
computer centers, computer conferences, individual scholars, and
|
|
libraries. Libraries are authorized to add the journal to their
|
|
collection, in electronic or printed form, at no charge. This
|
|
message must appear on all copied material. All commercial use
|
|
requires permission.
|
|
-----------------------------------------------------------------
|