Papers in PDF format

Issues for Future Research
There are three basic structures for texts:
1. Stream
2. Hierarchical object based
3. Network object based
Stream structured texts are based on a typescript model and are similar to those prepared with most word
processors. They are linear sequences of text data, consisting of a stream of words. Embedded markers
indicated events (such as the beginning of a new line or a tab). The stream model can apply to non-text
data as well; time-based media (sound, video) are almost always digitized as streams.
In object-based structures, textual objects such as paragraphs or lists actually exist rather than being
represented by events as in the stream based model. For example, in HTML (an object-based markup
system) each object is defined by a beginning of object marker (e.g. and an end-of object
marker (). By contrast, a word processor (such as Microsoft Word) marks a paragraph
strictly by the end of paragraph event, and except for a few selection commands, does not deal with text
objects per se. Anyone who has reviewed student papers (or conference proceedings) submitted in
machine-readable form has experienced the wide range of formatting events used by different authors to
define textual structures. On the other hand, there is only one way to define, for example, an unordered
list in HTML, which treats such lists as objects rather than as a sequence of formatting commands.
Software for publishing large documents (such as Framemaker) as well as markup systems developed
for large documents (such as most document type definitions in SGML) usually adapt a hierarchical object
based organization [Goldfarb 1990]. The hierarchical structure is traditional and the reasons for it are
twofold. First, it has significant advantages in simplifying the human information processing problems
arising from large structures [Lehman 1990]. Second, given the enforced linear structure of print, it is
easy to implement. However, as any author who has ever force-fit a series of ideas into a hierarchical
outline knows, the structure often does not fit the content.
Network object based structures attempt to deal with this problem by adapting an object-based model but
not requiring a hierarchical structure. Such structures are difficult to implement in print (although
footnotes and cross-references make the attempt); they are trivial in a computer-based document. They
place additional demands on the user in terms of cognitive processing.
In terms of this theoretical differentiation of text types, the exploratory study described above offers
evidence that users do not find that www-based implementation of the stream model and the shallow
hierarchical object based model (book, chapter, section) add value to printed versions except in terms of
currency. Unfortunately, the structure of our study did not allow us to distinguish between more deeply
hierarchical object based structures and network object based structures. The question for designers of
www-based educational and reference material is whether users find one or the other of these two
structures better for the communication of information, and how a web-based hierarchical structure
compares with a printed one in terms of user acceptance. We plan to test these questions in future studies.
Conclusion
As the Web's popularity has grown, the skills needed to find, read, and manipulate Hypertext documents
will become more common. At the same time, it is important that authors of www-based material design
and write them to take advantage of the new medium rather than mechanically translating from an older
form.
References