By Thomas Trickel
Ever since Vanevar Bush introduced the concept 
and Ted Hoff coined the term, Hypertext  and now
Hypermedia have held out the promise of making
information more accessible and understandable
through their ability to link related ideas and
concepts. Traditional paper based information is
limited by its medium. Traditional text is forced
by its medium into a mostly linear form. References
are limited to devices such as footnotes, sidebars
or parenthetical references which do not provide the
speed or convenience of access, that we in this
computer age are becoming used to. Hypertext on the
other hand allows text to be created and viewed in a
non-linear manner. Paragraphs can be linked
together in many different orders allowing the
information to be presented in other ways.
References and annotations can be stored in separate
documents, but they can still be connected to the
referring document. It is this ability to connect,
or link, portions of text that are related but not
necessarily contiguous that sets Hypertext apart
from traditional text. The promise of Hypertext is
then the promise of links.
Initially I thought that links were merely a
connection from one node to another. But my early
reading  introduced the idea of link types and
the possibility of an unlimited number of types.
This raised the idea that links could be more
complex, that a link could be more than just a
connector. A link could contain information about
itself and the nodes it was connecting. Information
contained by a link could be what the link does,
what the link is pointing to and how the link
relates the two (or more) nodes. An example of this
would be a link that when activated caused a pop-up
window to display a definition of a word. Three
pieces of information that this particular link
carries are: it causes a pop-up window to appear, it
points to a definition and it has two nodes that are
related by a definition. Other links could cause
another document to be displayed or a sound to be
played. Links could point to other paragraphs within
the existing document, to a different document on
the same machine or even to a document on a
different machine in a different country. Among the
relationships that a link could define are:
reference, expanded explanation or argues in support
This theoretical model proposes three properties of
Thus, it seems that links could have the capability
of containing more information than my original idea
that a link contained merely a pointer to another
node or nodes. How does this theoretical model
compare with two popular Hypertext implementations?
- The action the link causes in the user interface.
- The resource the link points to.
- The way two, or more, nodes are related.
Links in the World Wide Web
One of the most popular forms of Hypertext today is
the World Wide Web(WWW). The WWW uses plain (ASCII)
text documents that are annotated with a markup
language called HTML (HyperText Markup Language) 
to convey its information. In the WWW
implementation, links are created by using a markup
tag called an anchor which takes the form:
<a href ="URL">text used to identify the anchor</a>.
URL  stands for Uniform Resource Locators and is
the method that the WWW uses to link information.
The information contained in the URL defines what
type of node a link points to and where the node is
The action a link initiates in the user interface is
client dependant. Selecting a link causes most web
browsers to, either display the resource referenced
by the link, or, to start another application in a
separate window to display resource types that
browser cannot interpret.
Unfortunately, the WWW has no way of representing
how the nodes are related, other than what is
contained in the text used to identify the link.
Link information in the WWW is limited to the
current node's URL and the text of the link.
In the WWW the capabilities of the proposed three
link properties are:
- The links can cause one of two actions in the user interface. Either display another node
or start another application to handle the information pointed to by the link.
- What the link points to is defined by the URL contained in the anchor, or link.
- There is no way, other than what is contained in the text used to identify the link, of representing how the nodes are related.
The Internet Gopher
Calling the Internet Gopher a Hypertext application
might be stretching the definition a bit but I
believe a look at the implementation of the Internet
Gopher's links will prove instructive. Links in the
Internet Gopher are either generated on the fly by
the Gopher server or stored in a .links file. I
will concentrate on the links stored in the .links
file because I believe they are the most appropriate
for this discussion. A .links  file is made up
of multiple enteries of several lines of text with
keywords to identify the lines. A typical entry
The items in this list are the information contained
in a typical Gopher link. In addition to the
information that is contained in a URL, the Internet
Gopher adds Name and Numb. The Gopher+ .links
definition  adds a few more types of information.
Of the types added, Abstract is potentially the most
useful, allowing the person interested in the link
to see more information about the link before it is
- Name=National Weather Service Forecasts
The action a link initiates in the user interface is
client dependant. However, Internet Gopher clients
cause a browser's user interface to display another
menu screen, display a file or start another
With the addition of the Gopher+ definition a new
.links file entry can be defined to contain the
relationsip of the two nodes.
Links in the Gopher implementation:
- The links either display another menu screen, display a text file or start another application to handle the information pointed to by the link.
- What the link points to is defined in .links file entries.
- With the addition of the Gopher+ definitions it is possible for the link information to contain the relationship of the two nodes.
The Missing Property
Both the WWW and the Internet Gopher differ from the
proposed theoretical model by omitting the
relationship of the nodes connected by the link.
The WWW and the Internet Gopher implementations
could be extended to have a link property that
contained the relationship information. In both
cases new browsers would have to be created to use
the new link property.
The Internet Gopher protocol allows each link to be
sent from the server to the browser as a tab
delimited text field with the links seperated by a
carriage return. Thus, additional fields to be
interpreted by a compatible browser could be easily
added. This is how the the newer Gopher+ protocol
extends the older Gopher protocol. The Gopher+
protocol doesn't explicitly address relationship but
it could be added easily.
With the WWW's relience on HTML to add links to a
node the HTML code would have to be extended. The
browsers would have to be modified to recognize the
new extensions. Netscape does a similiar type of
extension to keep track of the date that a
particular link was visited. A Netscape bookmark
file link looks like:
to Netscape! (home of this utility)</A>.
The traditional link of <a href="URL">link text</a>
has been extended with the addition of ADD_DATE and
LAST_VISIT. LINK_RELATIONSHIP could be just as
easily added which existing browsers would just
ignore like they ignore the Netscape defined
The Future of Links
As we rely more and more upon computers to convey
our information the information that is being
conveyed needs to become smarter. Links in the
current implementation of the WWW aren't very smart.
Smarter links, links that contain more information
than the node type and location being linked would
be quite useful to users of the system. An example
of this is the classification of links. Currently
classifying links requires a person to be involved.
However, if links contained their own classification
information such as this link points to a document
on bicycles, travel and Costa Rica, a computer could easily
classify or search for them. In addition to aiding the
classification of links smarter links could contain other
information like abstracts and sizes of the linked to files that
would aid a user in his selection of the link.
Comments and Criticism
Comments and Criticism directed to:
firstname.lastname@example.org will be added to
this section for future reference.
About the author.
 Bush, Vannevar As We May Think Atlantic Monthly, July 1945, pp. 101- 108 or html version
 A WWW definition of the word hypertext
 Conklin, Jeff Hypertext: An Introduction and Survey IEEE Computer, Sept. 1987
 A Beginner's Guide to HTML
 A Beginner's Guide to URLs
 gopherd on-line man pages
 Gopher+ upward compatible enhancements to the Internet Gopher protocol