Information Technology Reference
In-Depth Information
do with (1) understandability, (2) origins, context and restrictions and (3) the way in
which the data and “metadata” are grouped together.
The reason for this separation is that given some digitally encoded information
one can reasonably ask whether it is usable, which is dealt with by (1). This is a
separate question to the one about where this digital object came from, dealt with
by (2). Since there are many ways of associating these things it seems reasonable to
want to separate consider (3) separately.
It could be argued that to understand a piece of data one needs
to know its context. However the discussion about “Independently
Understandable” in the previous section points out that OAIS does
not require understanding of all the ramifications so this separation
of context from understandability is reasonable, although it does not
mean that all context is excluded from understandability since a piece
of “metadata” may have several roles.
The packaging is something which is separate from the content. The next few
sub-sections briefly introduce these different categories; they will each be discussed
in much greater detail in separate chapters.
3.2.1 Understandability (Representation Information)
One type of “metadata” we can immediately identify is that which we need to
“interpret, understand and use” the digitally encoded information. OAIS defines
this as:
Representation Information:
The information that maps a Data Object into more
meaningful concepts.
An example of Representation Information for a bit sequence
which makes up a FITS file might consist of the FITS standard which defines the
format plus a dictionary which defines the meaning of keywords in the file which
are not part of the standard.
Figure
3.1
indicates that the Representation Information is used to interpret the
Data Object in order to produce the Information Object - something which one can
then understand and use.
The OAIS definition of
Information Object
is:
A Data Object together with its
Representation Information
.
This is a very broad definition.
Interpreted
using its
Yields
Data
Object
Representation
Information
Information
Object
Fig. 3.1
Representation information
