Papers in PDF format

Figure 1: HM Data Model Collections (Redrawn from [MSS93])
An imposed condition in the HM-Data Model is that all links must be encapsulated within . Browsing
is achieved by the means of the three operations ACCESS, ZOOM-IN, and ZOOM-OUT. When any is
ACCESSed its content is displayed. ZOOM-IN opens a collection to display the underlying content. ZOOM-OUT takes
the user back to the collection that was accessed just prior to the most recent ZOOM-IN. We thus have a structure,
which does not have to rely on explicit links, where users can browse up and down the hierarchies while keeping a
``well defined sense of the current location" [Maurer et al., 1993a]. Also, since at any moment of time a stack of open
may exist it is easy to generate a meaningful graphical trace.
It is important to note that although any collection can be a member of other collections this does not mean that the data
has to be duplicated: pointers may be used. Also recursive membership is both possible and meaningful.
Besides supporting multi-metaphor browsing [Maurer et al., 1993a] the HM-Data model incorporates a powerful query
mechanism in the navigational paradigm [Maurer et al., 1993b] thus providing users with an integrated environment.
Meta-data
One of the little addressed deficiencies of most WWW hypermedia systems is the lack of meta-data. Meta-data is
information about a document such as its title, author, date of insertion into the system, date of last modification, access
rights, expiry date, etc. It can also include user-defined information such as keywords and summary data. This
information can be used for a wide variety of purposes, just a few of which we mention here:
Meta-data information can form a basis for better searches).
Necessary statistics can be collected and categorised by date, user, etc.
As we discuss in Section 5 chunks of multimedia data can be linked to form personalised documents. Using
access rights, the customised documents can be made available to specific groups of people at specific times.
Perhaps most significantly in these days of fast moving change, only by having meta information available can
systems be more readily upgraded to new and/or better systems. It is interesting to note, for example, how readily
a system such as Gopher can be ported to Hyper-G [Maurer, 1995b].
Customisation of Documents
Undoubtedly, one of the thorniest set of problems that must be solved by the next generation of hypermedia systems is
that of copyright issues. This is a particular problem of concern for authors of courseware. In previous papers [Maurer,
1995a, Lennon and Maurer, 1996] we have elaborated the idea of creating documents, not by copying from other books
and journals, but by linking to publications for which we have library-like user rights. We suggest that ``information
brokers" will supply information rights, at a cost, to various organisations [Maurer, 1995a]. Within ``information hubs",