4. DIGITAL LIBRARIES
The context of NoVA lies in the development of digital library services, understood broadly. While there is no universally accepted definition of a digital library, it is useful to think of it as a series of interrelated services built on digital information content. The key user-related processes have been variously defined, perhaps most commonly as resource discovery, location, request and delivery. In order for resources to be discovered and used they must be described (i.e. metadata created) and organised. Services are then built on this organised content. In order for the effort expended to be worthwhile these services must be used, and for that to take place there must be some kind of user interface. It is the interaction which takes place at the interface which is the locus of NoVA’s concern. As Arms (2000, p. 160) has put it, "a digital library is only as good as its interface". We should add that in NoVA we have not been concerned with the case where the interaction is machine-to-machine except insofar as specialised applications (such as screen readers) are used to make the service accessible.
Digital libraries may be conceived of, on this definition, as analogous to physical libraries, and it is quite likely that many users will interact with both - the realisation of the hybrid library concept which has received attention in recent years (Brophy and Fisher, 1999). This posits that legacy (mainly print) collections will remain important for a considerable time to come and that services must be based on a managed mix of resource types. One of the key tools which enables access to both the digital and non-digitised content of such libraries is the Online Public Access Catalogue (OPAC), which may be seen as a gateway to the hybrid library.
The development of digital libraries has been informed by both theoretical and practical perspectives, to which the UK’s Electronic Libraries Programme (eLib) made a very considerable contribution. In the UK academic sector eLib led to the development of the Distributed National Electronic Resource (DNER) and more recently to the concept of an Information Environment. Other sectors have seen parallel (though perhaps not as advanced) developments and there is evidence that these are now converging towards national services. The local library or other institution remains the focus of access however, not least because it can offer localised information and support services to the individual user.
It is now difficult to differentiate meaningfully - as far as users are concerned - between "library" and other information services in the electronic landscape. Indeed there is considerable evidence that at least some groups of users tend to try to resolve their information needs first by use of general search engines and only move on to library services when that source fails (see, for example, some of the results of CERLIM’s current EDNER Project). It is unlikely, however, that. they would distinguish any one set of services as a "library". Increasingly portals are being developed to provide an access point to a range of such services, and it is now perhaps more meaningful to speak of the digital library as encompassing a wide range of services, accessed through a portal, which may be "internally" or "externally" provided and mediated.
The interface of choice for nearly all digital library services is the World Wide Web. Although significant changes are taking place in web technologies, this style of graphical user interface has rapidly become dominant and looks likely to remain so. From an accessibility perspective this has at least allowed standard approaches to be developed to try to ensure that all users are able to access all services. But the very nature of web pages makes them inherently inaccessible. The widespread use of graphics is the most obvious case in point, but concern also extends to the widespread use of tables and frames and to more subtle issues concerned with users’ perceptions and cognitive processes.
In the NoVA project it was decided that the best way to explore user behaviour in "digital libraries" would be to devise a set of realistic information seeking tasks and to ask users to undertake these with selected web-based resources. These resources would include what might be thought of as typical library resources (such as an OPAC) but would be extended to include both a search engine and directory, since these have become common access methods. Finally, after some deliberation, an online shopping site was included so as to give some evidence of user behaviour in what it might be argued is an increasingly important electronic information sector.
At the core of NoVA’s concerns, then, are the issues of digital library accessibility and usability. To quote Arms (2000, p. 143) again, "digital libraries are of little value unless they are easy to use effectively". This is particularly true for those who approach them with a visual impairment that all too often in the past has been treated as a side issue in designing the user interface.
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