Introduction - Advanced Digital Preservation - page 1

Chapter 1
Introduction
This chapter provides a quick view of why digital preservation is important - and
why it is difficult to do.
There is a need to be able to preserve the understandability and usability of the infor-
mation encoded in digital objects. Because of this focus on information we shall
often refer to digitally encoded information where we wish to stress the information
aspects.
However the basic techniques of digital preservation, discussed in many topics
on this subject, for example [ 7 - 12 ], focus, by analogy with traditional paper-based
libraries and archives, on preserving the media or bit sequences and preserving the
ability to render documents and images.
This topic addresses what might be termed the more advanced issues of digital
preservation, beyond keeping the bits and the ability to render, bringing into play
concepts of understandability, usability, knowledge and interoperability. In addition
it is recognised that there are rights associated with digital objects; there is concern
about how one can judge the authenticity of digital objects; there is uncertainty
about how digital objects may be identified and located in the future.
In responding to each of these concerns the likelihood is that additional digital
artefacts will be created (such as the specification of the digital rights) - which
themselves need to be preserved so they can be used in future when they are
needed!
Thus we argue that one must be able to preserve many additional different digital
objects if one wishes to really preserve any particular single digital object.
Part I of this topic provides the theoretical basis for preservation.
In Part II we provide evidence from a variety of sources using many types of
data from many disciplines, and show many tools which provide reasonable imple-
mentations of the techniques described here. These examples and much of the work
described in this topic are derived from the CASPAR project [ 2 ].
Part III addresses the important questions of how to keep costs under control and
how to make sure money is not wasted by preparing one's archive for independent
evaluation.