@1. On-line Text Processing and Associative Access
In the last few years several new approaches to text access have appeared, connected with the development of associate text navigation, hypertext and hypermedia technologies. Text-based research, especially through reference materials, is generally an associative process. If you have a smal amount of information about a topic, you begin perusing your reference materials by looking for those topics you have already associated to your domain.
Employing this technique for scanning and searching on-line text is very useful. According to McGrew and McDaniei through the use of content-based or associative access methods, on-line text systems have become capable of supporting this type of research. Some systems are keyword sensitive in the manner that book indexes are, but if the particular word to be used has not been anticipated by the documentalist, it is not usable as a search key. Other systems index every significant word allowing any kind of association. This technique requires a full text search. Noise references are often produced using these systems, although it is possible to filter about some of the noise by carefully defining the context of the search by adding limiting criteria. However, associative navigation of a text database can be very helpful, but systems that use it exclusively often require the user to spend much time to gaining familiarity with appropriate search strategies [McGrew McDaniei 1989].
@2. Prospects of Hypertext
Accessing and perusing text in a non-linear manner through che use oi software links between document element, as well so through sequential and associative methods means hypertext. As Barrett points our, on-ilne Page 70 documentation systems represent the assault on a central concept of Western culture, the book itself: a linear narrative moving in time, occupying real space, with a beginning, middle? and end. Hypertext and hypermedia environments alow self-authoring texts and non-linear documents, creating a mirage of depth in the collapse of space and time within the computer. An infinitely evolving text that tracks momentary cognitive processes within the individual reader-author [Barrett 1988].
Unlike paper texts, where information is generally expected to be read in a sequential manner, hypertexts allow readers to navigate their own paths through information. They exploit the interactive nature of the electronic medium and open up many new possibilities. Tipicaliy, the author must provide links between related pieces of information in a manner that allows readers to choose which links they wish to explore. Links may be used to direct readers to additional information in much the same way that footnotes and glossaries do in paper texts5 or more direct links may be provided between related pieces of information. In either case readers can view the related information by simply pointing to a cbottoif or other indication on the screen [Woodhead 1991].
Taking advantage of this new technology, complex documentation systems may be designed so that they meet the user needs in a greater variety of contexts, extending or adding value to freedom of movement1 and associative possibilities. Access in this sense does not only mean the ability for users to read, but also to 'write' their own information environments, without disturbing the integrity of original texts [Rubens, 1989].
Hypertext makes use of sophisticated database management techniques and requires the information designer to deconstruct the paper text into a collection of fragments embedded in a knowledge base which can then be accessed by specially designed retrieval software. The hypertexteal model is based on the assumption that human reasoning occurs through association, so it receives increasing attention as a framework for effective and efficient communication of knowledge. Only hypertext systems alow an active construction of knowledge, while the development of traditional on-line information systems has generally led to the production of static knowledge representation systems, that is closed systems objectifying theories.
By treating text as a collection of nodes - as Carlson suggests - the information may be ordered hierarchically or in association networks, based on the readers preference or upon the requisites of the task being supported. Readers can quickly navigate through a large body of material using graphic browsers which show ideas as icons or as block diagrams. Additionally, the webs or patterns of links established among the nodes provide resear- Page 71 chers with a trace device for analysing how individuals or group use documentation. It is possible to establish an individual view to a generic document: if the links between nodes are typed, the user may call up a specified category, and thus views the data through a pre-established filter [Carlson 1988].
@3. From Hypertext to Hypermedia
Both hypertext and hypermedia belong to a more general class of multimedia, but a distinction is to be made between hypertext and hypermedia, even if the two terms are often used interchangeably. Although hypertext structurally refers to textual information, the term is also commonly used to refer to bothes of information containing graphics and images as well. On the contrary, the term hypermedia is generally used to refer to information containing a high proportion of graphics and images, and is almost always used where the information also includes video sequences or any form of animated information. Following definitions given by Wood-headf hypermedia can not only be seen as a new way to structure groups of documents seamlessly, but rather as a potentially unifying paradigm for managing diversityf where each unit would require specialized and independent tools. Their main features can be summarized as follows: non linear reading and augmentation of heterogeneously formatted materials; selection by natural language, reduced keystroke techniques and graphical overviews; exploration/ browsing; integration of heterogeneous media (text, graphics, sound, video, executable programs) and respective storage mechanisms; priority of content over form; one-to-one links [Woodhead 1991].
With respect to conventional information systems, hypermedia possess many advantages. Taking a single written work as an examplef the efficiency with which the user can extract the material sought depends largely on facilities provided for categorizing, referencing or filtering information, which are not essential to the content of such a work, but able to enhance it in some way. The printed page is to be considered restricted to text and to simple static two-dimensional graphics. Even if it is possible to provide a book with a video cassette, a computer or optical disk, or an audio cassette, there is no direct means of following a reference from one medium to the exact point of another.
By contrast, hypermedia can be compressed so that great quantities of information can be held on the same floppy disk and the user can have on hand a personal storage capacity equivalent to that of a reasonably sized Page 72 library and may be able to consult this huge amount of data creating his own "informational world". As some experts affirm, the result is that authors are often forced to orient their works to specific narrow authence, while hypermedia systems support Verbose' and cfold-away' modes, in which annotations or auxiliary information may be...