C H A P T E R 1
used to find books; for example, you can search for the books in the card cata-
log by author or by classification (according to the Dewey decimal system, or
some other system). But metadata does not have to be limited to one type of
description. You can also find out which books are oversize and are placed on
a separate shelf. Knowing which metadata will become the most useful is
impossible to say in advance. To the librarian, the book classification is the
most important. To the historian of the printing industry, the size of the book,
its age, and the number of pages will be the points of interest. It is also hard to
say what is data and what is metadata. The distinction may depend on how the
data is used.
Now, regard the book as an object, and the information about it as an informa-
tion object. A book has a number of properties, such as whether the book is
available or not, which language it is in, where it is in the library, who has
recently borrowed it, and so on. Those properties the attributes of the book
(what determines its bookness) and the values of those attributes are all part
of the information object.
Metadata applications are similar even when used in different ways. The
underlying information structures are the same, irrespective of what is done
with them when they are presented to the user. This means that there are
potentially an infinite number of applications, which can cover any area in the
universe. Of course, it is not possible to describe all of them in one book, but it
is possible to describe the general principles behind them. And so, let us look
at a few scenarios.
The Library Visit
The library community already uses metadata to a large extent; indeed, the
library community has been driving the development of metadata technologies.
The library card catalog is probably the best-known example of metadata in
existence, and also the one with the best-established pedigree.
Lisa Simms, for instance, is studying at the University of Hawaii to be a
teacher. Today, she needs to find a book by the French pedagogue C lestin
Freinet, famous in Europe for his development of a participatory school sys-
tem. She switches on her computer and looks up Freinet in the library search
It turns out that there are no books by him in the library, so she turns to the uni-
versity search engine, and at the same time types in her query into her regular
The regular search engine found a number of hits on phrenology, the science
of divining people s characteristics by the bumps on their heads.
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