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Hypertext Links

Document access without paper

From "Migration",  Access to Wang, June 1995
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Wang's INFO document facility was introduced more than a decade ago as a means of providing access to information without paper. Though a good idea at the rime, it has been largely forgotten.

But INFO is similar in important ways to trendy products like Lotus Notes, Microsoft Windows Help files, Adobe's Acrobat reader, Apple's Hypercard and the World Wide Web (an Internet service): All are forms of hypertext.

The essence of hypertext documents is links, or jump points allowing readers to leap from concept to concept according to their interests or needs.

In most forms of hypertext, these links are shown using typographic differences, such as highlighted words or phrases within text, where the user can "drill down" for more derail by clicking on a passage.

Symbols, pictures or buttons can also be used as link indicators, and links that tie to other forms of information - pictures, sounds, movies or file transfers - have become practical.

Whatever the visual clue or the form of the resulting presentation, it's the links that make it hypertext.

As the information technology industry gropes for a more effective means of presenting text material on-line, it's worth looking back at the efforts made by Wang in the mid-1980s and compare them with mt)re recent developments.

The Wang INFO Facility

The Wang INFO facility consists of three major elements: the INFO utility, INFO documents (specially-formatted text files) and a catalog of installed INFO documents, 80-character consecutive files. These consist of four sections: a header area, the table of contents, the main body text and an index. The header describes the number of lines in the sections, the title of the document and the locations of the sections. The table of contents contains paragraph numbers, titles and the record number where the paragraph begins in the main text section. Body text is presented as normal characters, except that Field Attribute Codes (FACs) can be inserted within this text to make passages stand out; typically, only underlines are used within INFO documents. Finally, the index section (if present) provides an alternate means of finding passages in the body text.

INFO documents are distributed with software releases or are available for purchase from Wang. The INFO utility performs all normal functions, including document display and maintenance of the document catalog.

When run directly (run INFO in the system library), INFO shows a list of all of the documents within a library that have been installed on the system. No INFO document can be used unless it has been installed.

The document viewer displays a split screen, in which the upper half shows table of contents entries and the lower half displays the referenced text. Moving to another line in the contents causes a corresponding move in the body text window.

As with the Wang symbolic debugger, normal control keys for screen movement apply to the window where the cursor is placed. For example, if you press PF5 the active window moves down a page. It is also possible to switch either window to "full size," temporarily blocking the view to the other window. Unlike the debugger, INFO windows are fixed in dimensions, and the entire area of 24 lines by 80 columns is used by the application.

If the table of contents is thorough, INFO's links make it relatively simple to find the answer to a particular question. The reader can also browse the contents and select items randomly. INFO links work only within one document; there is no way to jump to sections in other documents.

Like other proprietary formats, INFO documents have no application outside of Wang systems.

You can develop your own INFO documents using Wang's INFOGEN product or by creating the consecutive files through other means, including manually building files within a text editor. Application programs can call specific sections of INFO documents by linking to INFO and passing the topic and subtopic names through the OPTIONS GETPARM.

Note that while calls from application programs are dynamic - referring to document files at run-time - the INFO documents must be installed correctly prior to this call.

Windows Help Files

The Help facility within Microsoft Windows and its application programs represent another form of hypertext.

The Help browser is included with the Windows product, and .HLP files are distributed with nearly all Windows applications. Help files can he called from within a program or directly from the File Manager by double-clicking on a file name. Help files can use pictures and typographic features, such as type sizes, styles, weights and colors. Text wraps to fit the current size of the Help window, and the window can be re-sized by users according to their needs.

Two types of links come with Help documents: links to definitions of terms (identified by a dotted underline) and links to other areas of the text (shown with full underlines).

Most Help files have a table of contents, hut it is also possible to search them using identified keywords by pressing the Search button. The reader can back up to a prior topic by pressing the Back button moving one link back, or return to prior topics with the History button. Glossaries are also present in some Help files.

Like other Windows applications, the user may use the keyboard or mouse to move within the Help browser, though the mouse is often more practical.

Most Windows applications have links to their respective Help files that retrieve information appropriate to the current action - in other words, context-sensitive help. The Windows convention for retrieving this information is to press Fl. Links to Help files are dynamic, and the Help browser will display an error message if the Help file is not in its expected location.

Creating your own Help files is difficult enough that a small industry is devoted to products to meet this need. Help files must he compiled like programs, and the source syntax can he difficult.

Most Windows language products (e.g., Microsoft Visual Basic and Visual C++ or Borland Delphi and C++) provide some means for Help development, and other products are available separately. Consult vendors and manufacturers for details.

The World Wide Web

The World Wide Web (WWW, or just "the Web") is one of the most interesting and important developments in information technology this decade.

A multimedia hypertext medium with network distribution as its foundation, the Web provides a point-and-click interface that can link to information anywhere within the world while shielding the user from the complexities of the process.

Web links can retrieve hypertext documents or perform several other functions, including file retrieval using the File Transfer Protocol (FTP), menu access (Gopher services), news groups (a.k.a. USENET) or simple electronic mail. If the client can handle them, Web documents can also deliver sound, movies, pictures or live video feeds.

WWW components consist of clients, servers, WWW documents (often known as "home pages") and the networks linking them. Clients are user programs (browsers) that request and display WWW documents; servers are the host programs that answer these requests. Internet-based networks (TCP/IP) are typically assumed to connect these two entities, though local disk files or other sources can also be accommodated. Besides marked links, users can also search for text within the Web document.

Using WWW pages is similar to using Windows Help files: point and click (or tab) to a link and select it to see additional information. Web pages are retrieved dynamically. The links can refer to information within the same document (like bookmarks in some word processors) or outside the current document; more on this later.

Graphical elements, including marked buttons and pictures, can also be used to mark links.

Unlike applications such as Wang's INFO and the Windows Help facility, the World Wide Web is an architecture - not a product, but a specification for products. The WWW specification is broad enough to allow a variety of products to be developed to fit the individual needs of the client.

For example, the Lynx viewer (a client; see Figure 1 for example) displays WWW documents on text-only terminals, while graphical viewers (Mosaic, Netscape, NetCruiser, etc.; see Figure 2) take advantage of the additional capabilities of the client machine (Windows, Macintosh or X Window terminal). In either case, the same Web document can be displayed on either, as shown by this comparison of the same document on text and graphical viewers.

The distribution capabilities of WWW architecture are equally important: note the address line (http://www.cern.ch/public) near the top of the screen in Figure 2. Translated, this Universal Resource Locator (URL) identifies the type of medium (http, a hypertext document), its location (www.cerh.ch, the CERN labs in Switzerland), and the document name (default.html). A link within this document could easily refer to any other known page on the Internet, anywhere in the world. (Recognizing this capability, most Web viewers do not come with complete documentation. Instead, a small WWW document is provided that includes links to the current online version wherever in the world it may he stored.)

Setting up your own Web document distribution requires setting up a server, installing client software and providing access to the files. Creating your own Web pages with the Hypertext Markup Language (HTML) is surprisingly easy, and you should be able to find a number of hooks on the subject in bookstores. Server software is available for little or no cost for Unix, VAX, PC and Windows NT systems but requires some effort to set up. Client software may be run on the host (Lynx) or from desktop systems, and free or low-cost systems are available.

Networks provide the easiest means of getting to your documents but local file storage can also be used. Naturally, you will need to connect your system to the Internet to exploit links to other part of the world.

The Future

In the search for a viable means of providing electronic access to published material, many approaches have been taken. Hypertext provides a way to meet some user needs, but its success is tied to the skills and foresight of the document authors. Undoubtedly the medium will change as we continue our march away from paper.


Figure 1: Sample Document in a World Wide Web Text Viewer


Welcome to CERN (p1 of 3)

   CERN logo
   [1]Version Française

                                 THIS SITE
     _________________________________________________________________

   [2]Languages
   [3]Help
   [4]Contents
   [5]Credits
   [6]Your comments
   [7]Related Links
   [8]Experiments

                              [9]Search button
     _________________________________________________________________

                                  GENERAL
     _________________________________________________________________

   [10]Users Pages
-more- http://www.cern.ch/public/Welcome_fr.html 

Figure 2: Sample Document in a World Wide Web Graphical Viewer

[Sample web browser screen showing the
CERN welcome page]

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Copyright 1995 Dennis S. Barnes
Reprints of this article are permitted without notification if the source of the information is clearly identified