Information Technology Reference
In-Depth Information
25.1.1.1 Preservation
We need first some methodology by which to test the basic claim that someone is
preserving some digitally encoded information; without such a test this is a mean-
ingless claim. OAIS introduces the, quite reasonable, test that the digital object must
somehow be useable and understandable in the future. However by itself this is
too broad - are we to be forced to ensure that the digitally encoded designs of a
battleship are to be understood by everyone, for example a 6 year old child? In
order to make this a practical test the obvious next refinement is to describe the
type of person - and more particularly their background knowledge - by whom
the information should be understandable. Thus OAIS introduces the concept of
Designated Community
, defined as an identified group of potential Consumers
who should be able to understand a particular set of information. The Designated
Community may be composed of multiple user communities. Note that a Designated
Community is defined by the repository and this definition may change/evolve
over time.
Bringing these ideas together we can then say, following OAIS, that preserving
digitally encoded information means that we must ensure that the information to
be preserved is
Independently Understandable
to (and usable by) the Designated
Community.
We are clearly concerned about long term preservation, but how long is that?
OAIS defines
Long Term
as long enough to be concerned with the impacts of
changing technologies, including support for new media and data formats, or with a
changing Designated Community. Long Term may extend indefinitely.
25.1.1.2 Definition of the Designated Community
An important clarification is needed here, namely that the definition of the
Designated Community is left to the preserver. The same digital object held in dif-
ferent repositories could be being preserved for different Designated Communities,
each of which could consist of many disjoint communities.
The quid pro quo is that those funding or entrusting digital objects to the repos-
itory can judge whether the definition of the Designated Community is appropriate
for their needs.
25.1.1.3 OAIS Conformance
OAIS conformance was discussed in some detail in Sect. 6.1. The standard
itself defines conformance in terms of the Information Model and the mandatory
responsibilities.
OAIS introduces a number of important concepts and conformance criteria; how-
ever this is not enough on which to base a certification scheme. The next section
describes some of the factors which must also be taken into consideration.
