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turns out to consist of two categories,
`content data object description' and `envi-
ronment description'. Each of these con-
tains (proposed) elements that can tell
something about the conceptual aspects
of the object we are preserving, e.g. in the
case of the first:
- `significant properties', defined as
`properties of the Content Data Object's
rendered content which must be
preserved or maintained during successive
cycles of preservation process';
- `functionality', defined as `... any functional
or `look and feel' attributes of the rende-
red Content Data Object, in regard to its
current manifestation in the archival
store'; this intends to describe the current
technical properties;
- `description of rendered content', defined
as `... Content Data Object's content, in
regard to how it should be viewed and
interpreted by users'.This includes
clarification of potentially ambiguous
data, definition and description of data
structures, etc.;
- `documentation', defined as supporting
documentation necessary/useful for
display and/or interpretation of the
Content Data Object;
- in the case of the second, the `output
format' of the `Display/Access Appli-
cation', defined as description of
the output to be expected from the
Display/Access application.
t means we have no fewer than five
metadata elements that could contain
information on what should be rendered
and presented on the screen. How all these
elements relate to each other, if at all, is
unclear. Another issue in this approach may
be that the digital object is only considered
to be a technical entity, and as such always
seems to be at the centre of attention,
not the intellectual object. Based on the
question of what should be preserved, one
would expect that it would be the other
way around, but it is not.To be more pre-
cise, in general we want to preserve the
intellectual expression (object, if you like),
not the digital components of which it
to preserve? Is it the intellectual content
with the functionality it has to have in
order to make sense and achieve its pur-
pose, or is it the digital components that
are necessary to reproduce it or both?
One of the basic notions in a digital envi-
ronment is the difference between what is
shown on the screen and what is stored
on the disk or medium.There isn't even
always nor does there have to be - a
1:1-relationship between them. A digital
component may contain one or more
records, or, conversely, one record may
consist of more than one digital compo-
nent (e.g. in the case of a multimedia
record). In many publications this distinc-
tion is not explicitly made and it is there-
fore not always clear what the subject of
discussion or the object of preservation is.
In general, there is recognition of the dis-
appearance of physical entities, but it seems
as if the consequences of this notion are
not always drawn.
t is the message or the intellectual con-
tent which the author or creator inten-
ded to convey that has to be preserved.
That content has a context, form and
structure and in some cases also behaviour
(e.g. spreadsheets). Be it as it is, the termi-
nology used is confusing and not consis-
tent on this point. My view is that `digital
objects' should be seen as objects having
both conceptual and technical aspects that
are closely interrelated. As a consequence
of the explanation given above, a digital
object may consist of more than one
`digital component'.The definition given
in the OAIS model is therefore insuffi-
cient. Moreover, the implications of this
concept for the model are not yet adequa-
tely considered.The distinction between
digital components and intellectual objects
as different views or entities requires, as
indicated above, not a one-to-one, but a
many-to-many, relationship.
hat does the OAIS information
model and the proposed metadata
set say about the conceptual or intellectual
aspects? Taking a closer look at what is
meant by representation information, it
consists per se, because, if one thing is
obvious in a digital world, it is the fact
that these digital components will change
over time. Even rigid standardisation will
not prevent that, although in the future
adequate technologies may probably
emerge that make things easier in the area
of preservation.This is also why in some
reports the preservation of digital objects
(i.e. their components) in their original
format(s) is recommended.What we want
to achieve, however, is that in the future
we will still be able to see, read and
understand the documents or other infor-
mation entities that were once produced
for a certain purpose and in a certain
context. In trying to achieve this, we of
course need to preserve these digital com-
ponents, but, as information technology
will evolve, these components have to be
migrated or in some cases emulated to be
usable on future hard- and software plat-
herefore, one of the issues is to iden-
tify what the intellectual aspects are.
The emerging notion of `Significant
Properties' seems to acknowledge this. In
this metadata set, it is identified as an ele-
ment and may serve as a description of
intellectual aspects, if only it is established
as such.
inally, special attention has to be paid
to the so-called `underlying abstract
form' (sub-element of `Content Data
Object Description'), a notion that has
been introduced and coined by the
CEDARS project. Its definition is: a
`human readable description of the
Underlying Abstract Form of the Content
Data Object'. It intends to provide infor-
mation about implicit structures (e.g. files
and relationships) that should be repre-
sented correctly to render or access the
`Object'. As such, it seems to address the
relationships between different (digital)
objects and not the structure of one single
intellectual object, for instance.To avoid
this confusion I would like to suggest
making a clearer distinction between
intellectual and `technical' or physical