Page 104 - Building Digital Libraries

General-Purpose Technologies Useful for Digital Repositories

In the above example, we see an EAD snippet in which a series and items
have been defined. This allows an EAD record to capture the structural
relationships that each child has with its parent. This offers EAD systems
interesting opportunities in regard to the display and linking of elements
within an EAD document, given the shared nature of the relationships. This
gives the metadata object the ability to become an information object itself.
This aspect allows XML metadata to exist outside of its parent systems and
act almost as a surrogate for the object that it describes, making the data
more meaningful to other organizations like libraries or search providers.

Metadata Becomes “Smarter”
How exactly does metadata get smarter? As an XML document, metadata
fields can have attributes and properties which can be acted upon. More-
over, by utilizing XSLT and XPath, data can be manipulated and reordered
without having to rework the source XML document. XSLT commands like
xsl:sort and position(), last(), xsl:for-each, xsl:for-each-group, xsl:if, and
xsl:when offer users the ability to act upon data within the XML document
by tag, attribute, or tag contents that separate the content from display. But
this extends beyond simple data manipulation. The ability to illustrate rela-
tionships and interlinks between documents—the ability to store content
or links to content within the metadata container—each of these options
is available through XML or an XML-based system. As noted above, the
document becomes an information object itself, having its own “metadata”
and properties that can be leveraged both inside and outside its parent
system. Systems like DSpace and Fedora that can use and produce object-
oriented metadata objects like METS (Metadata Encoding and Transmis-
sion Standard) can be used outside their parent systems as surrogate items.
Surrogates can then be utilized within a remote system to stand in for and
link to the parent item. Most digital repository systems create a number of
metadata objects for each document stored, creating metadata objects for
structural, administrative, and bibliographic data. METS-based systems use
the METS format to bind these individual objects together as a cohesive
whole—but in doing so, they create “smart” metadata that are their own
information objects.

Metadata Becomes “Connected”
One of the most exciting developments related to metadata in libraries has
been the move to understand how linked data concepts could improve and
enhance existing metadata models and turn library metadata from a col-
lection of strings into something that is much more actionable. Consider
the current way in which libraries handle control vocabularies within their
bibliographic data. Presently, libraries utilize a collection of strings—in

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