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4c. Preservation Metadata:
Introduction
Where does Preservation Metadata fit in the larger world of metadata?
The salient characteristic of Preservation Metadata about
objects is that the information describes attributes and issues
that are useful over the long-term life of the objects. The conventional
view of metadata assigns them into three categories
– Administrative, Descriptive, Structural. This division doesn't
highlight the common purpose of preservation metadata.
The OAIS model introduces another view, distinguished by the long-term
function of the metadata. Four new categories—Reference,
Context, Provenance, and Fixity Information—grouped under
the umbrella term Preservation Description Information (PDI),
make the long-term issues explicit. A fifth category, called
Representation Information, contains information about the viewers
and programs needed to process particular digital objects. A
sixth category, Descriptive Information, contains more ephemeral
metadata—the information used to aid
searching, ordering, and retrieval of the objects.
Preservation Description Information
1) Reference Information: enumerates and describes
identifiers assigned to the content information such that it can
be referred to unambiguously, both internally and externally to
the archive (e.g., ISBN, URN).
2) Provenance Information: documents the history
of the content information (e.g., its origins, chain of custody,
preservation actions and effects) and helps to support claims of
authenticity and integrity.
3) Context Information: documents the relationship
of the content information to its environment (e.g., why it was
created, relationships to other content information).
4) Fixity Information: documents authentication
mechanisms used to ensure that the content information has not been
altered in an undocumented manner (e.g., checksum, digital signature).
Representation Information
Representation information facilitates the proper rendering, understanding,
and interpretation of a digital object's content. At the most fundamental
level, representation information imparts meaning to an object’s
bitstream. For example, it may indicate that a sequence of bits
represents text encoded as ASCII characters and furthermore, that
the text is in French. The depth of the representation information
needed depends in part on the designated community for whom the
content is intended.
 Preservation
related metadata standards are developing across the digital
preservation landscape. As of 2005, recent developments include
a data dictionary from PREMIS, the
NISO Technical
Metadata for Digital Still Images, and METS, which is being
actively taken up by a number of digital preservation initiatives.
Each organization has to navigate through the changing metadata
scene to consider the standards, practice, protocols, and
tools that fit their digital preservation development approach
and stage. As preservation metadata practices stabilize,
it will be less necessary for individual organizations to
devise interim approaches, but many organizations are finding
it necessary to forge ahead with an eye towards community
developments and standards.
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0101 The technological
challenge is to adapt, adopt, and develop appropriate tools
and techniques (e.g., JHOVE, PRONOM, Xena) as the organization
determines short-term and long-term strategies for addressing
evolving preservation metadata requirements. How do community
developments on preservation metadata fit into the organization’s
digital preservation development plans? What will it take
to make new or legacy digital objects ready for long-term
preservation?
$$$$ Preservation metadata costs
are beginning to shift from handwork approaches to automated
processing and handling. Resources are better spent on developing
effective processes and workflow than on manual
operations. Open source software and tools require resources
to effectively incorporate them into an organization’s
digital preservation program. |
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