Principles
and Specifications for Preservation Digital Reformatting
Library of Congress preservation specifications for digital
capture; structural, administrative, and descriptive metadata; and delivery
are based on current standards and best practices in the Preservation community,
LC experience through the National
Digital Library Program (NDLP), and new approaches developed by the
LC Preservation Directorate.
Underlying Principles
- Retain an analog version of digitally-reformatted items until the Preservation
Directorate has confidence that the life-cycle management of digital
data will ensure access for as long as, or longer than, the analog version.
The analog version may be the original item, paper facsimile, or microfilm
copy, and may be restricted for use after the digital reproduction is
available.
- Ensure the appropriate handling and treatment of originals, and work
with curators, recommending officers, and other Preservation staff to
make decisions about disbinding, housing, and related matters.
- Minimize handling of originals in the digital reformatting work to
assure the best digital capture of an undamaged original, as well as
the longevity of the original item, especially if it is to serve as the
analog version.
- Ensure that the digital master file will allow a broad range of future
use, including planned phases of delivery,
by employing appropriate standards and best practices.
- Capture
the highest quality digital image technically possible and economically
feasible for large-scale production, while optimizing the potential for
longevity.
- Archive
a digital master file that is free of, or minimizes, artifacts introduced
by the reformatting process, whenever possible.
- Ensure
the completeness of all materials being digitally reformatted to a standard comparable
to that employed for preservation microfilm.
- Optimize digital images of paper-based text materials for use in creating
a new paper facsimile, when appropriate.
- Employ economical, automated methods to create machine-readable text with minimal encoding (such as that recommended by the TEI
in Libraries Guidelines) to provide access with searchable text and allow for future expanded use and encoding, when appropriate.
- Employ standards and best practices for structural, administrative, and descriptive metadata that will optimize interoperability with LC, national, and international digital library efforts, and facilitate the life-cycle management of the digital objects.
- Document digital master file contents with MD5 checksums (or a similar tool) and use them to ensure the data integrity of master files through back-up and migration.