Information Technology Reference
In-Depth Information
On the other hand the terminology is extremely useful when intercomparing dif-
ferent archives, especially those which have a different disciplinary background and
hence a different vocabulary.
6.5 Information Flows and Layering
OAIS describes a number of logical flows of information within a repository. This
topic will not discuss these flows. Instead we introduce a different view which will
help us later on in the discussions.
It is useful to think in general what happens when one archives digital objects, as
illustrated in Fig.
6.11
The idea behind this diagram is that in order to preserve a digital object one
needs to capture, during the ingest process (starting at the upper left of the figure and
following the curved arrow, a number of aspects about it in order that one can satisfy
the concerns raised in
Chap. 1
. For example one needs to know about the access
rights associated with it; one needs to capture aspects of the high level knowledge
associated with it; one needs to understand how to extract numbers and other data
elements from the bits, and so forth.
This is presented as layers because one can imagine changing the lower layers
without affecting the layers above. For example the High Level Knowledge to be
captured may change depending upon the Designated Community; such a change
would not affect the Access Control information. Also the Access Control infor-
mation is likely to be applicable to many different Information Objects. Similarly
the information may be encoded in different ways, which would alter the bit-level
descriptions, but the High Level Knowledge would be unaffected, thus the latter
could apply to many of the former.
It is useful to think about these kinds of variations in order to identify
commonalities and differences.
We will return to these considerations later, in Part II.
6.6 Issues Not Covered in Detail by OAIS
As noted at the start of this section OAIS does not address all issues to do with digital
preservation. Some of these topics fall outside the remit of the OAIS standard; some
of these were left for follow-on standards, while still others were thought to be too
specialised or too immature to be amenable to this type of standardisation.
