Information Technology Reference
In-Depth Information
One useful way to understand why this breakdown may be useful is
to consider a number of different variations.
For example two copies of a simple message (i.e. a piece of informa-
tion) may be contained in two text files (i.e. in the same format), but
in one case the message is written in English and in the other case it
is in French (needing different dictionaries).
Similarly one can have the English text both in a PDF and a Word file
- two different formats but needing the same dictionary.
In general breaking things down into smaller pieces means that one is
not forced to treat objects as a sticky mess. Instead one can deal with
each (smaller) part separately and usually more easily.
When this is coupled with the fact that Representation Information is an
Information Object that may have its own Data Object and other Representation
Information associated with understanding that Data Object, as shown in a compact
form by the
interpreted using
association, the resulting set of objects can be referred
to as a Representation Network. Detailed examples will be provided in Part II.
In the extreme, the recursion of the Representation Information will ultimately
stop at a physical object such as a printed document (ISO standard, informal stan-
dard, notes, publications etc). This allows us to make a connection to the non-digital
world. However use of things like paper documentation would tend to prevent “auto-
mated use” and “interoperability”, and also complete resolution of the complete
Representation Network, discussed further below, to this level would be an almost
impossible task. Therefore we would prefer to stop earlier, and this will be discussed
next.
As the final part of this rush through the OAIS concepts we turn to something a
little different in order to answer the question
“How much 'metadata'?”
A piece of Representation Information is just another piece of Information -
hence the name Representation Information rather than Representation Data. In
order for there to be enough Representation Information it has to be understand-
able and usable by the Designated Community - in order to be used to understand
the original data object. However what if this is not the case?
The Representation Information may be encoded as a physical object such as
a paper document, or it may be a digital object. In the latter case we can sim-
ply provide Representation Information for that digital object. If the Designated
Community still cannot understand and use the original data, we can repeat the
process. Clearly this provides us with a way to answer the “How much” question:
we provide a network of Representation Information until we have enough for the
Designated Community to understand the Data Object. OAIS defines:
Representation Network:
The set of Representation Information that fully
describes the meaning of a Data Object. Representation Information in digital
forms needs additional Representation Information so its digital forms can be
understood over the Long Term
.
