AIP: The internal representation of an object into the Digital Preservation Repository, including all data generated upon ingest (e.g., descriptive metadata) needed to manage and preserve it. See also DIP and SIP.
BIT
: The fundamental unit of digital information storage, which can have a binary value of either 1 or 0.
BIT ROT
BITSTREAM
A sequence of bytes, which has meaningful common properties for the purposes of preservation. A bitstream may be a file or a component of a file.
BORN-DIGITAL are assets that originated in digital form, such as Web sites, wikis, e-books, digital sound recordings, and email.
BYTE
A unit of digital information and measure of data volume, normally equivalent to eight bits.
CHECKSUM is a function used for validating data integrity. Also referred to as MD5 (Message-Digest algorithm 5). An algorithm or formula is applied against the source (typically a file and its content, such as the image of a scanned page from a book) in order to generate a unique, 128-bit hash value often called a checksum. In digital preservation processes, the MD5 checksum from when the content was created is compared to another checksum created after the content has been received or stored over a period of time. The values are compared and, if they match, this indicates that the data (e.g. the scanned page image) is intact and has not been altered.
CRAWL: The activity of using software to recursively download web documents by following links. There are a variety of crawl methods, including: focused crawl, smart crawl, incremental crawl, targeted crawl, and customized crawl.
CRAWLER: Also known as a spider or robot. Software that automatically traverses the web by downloading documents and following links from page to page.
DESCRIPTIVE METADATA: Metadata used for the discovery and interpretation of the digital object. Descriptive metadata may be referred to externally or indirectly by pointing from the digital wrapper to a metadata object, a MARC record, or an EAD instance located elsewhere. Or, descriptive metadata may be embedded in the appropriate section of the digital wrapper.
DIGITAL ART may be as simple as digital photography or it may be much more complex in that it could be mixed media, dynamic, or could require recreation of an entire installation to render it effectively. More complex forms of digital art will likely require one-off solutions.
DIGITAL OBJECT: An entity in which one or more content files and their corresponding metadata are united, physically and/or logically, through the use of a digital wrapper.
DIGITAL WRAPPER: A structured text file that binds digital object content files and their associated metadata together and that specifies the logical relationship of the content files. METS is an emerging, XML-based international standard for wrapping digital library materials. All of the content files and corresponding metadata may be embedded in the digital wrapper and stored with the wrapper. This is physical wrapping or embedding. Or, the content files and metadata may be stored independently of the wrapper and referred to by file pointers from within the wrapper. This is logical wrapping or referencing. A digital object may partake of both kinds of wrapping.
DIP (DISSEMINATION INFORMATION PACKAGE): An external representation of an object exported from the Digital Preservation Repository, optionally including an Archival Information Package, Submission Information Package, and object metadata. See also AIP and SIP.
EMULATION: The imitation of a computer system, performed by a combination of hardware and software, that allows programs to run between incompatible systems. Or, the ability of a program or device to imitate another program or device.
FEDORA (http://www.fedora-commons.org/) (Flexible Extensible Digital Object Repository Architecture) is a software framework to construct and maintain repositories of digital objects.
FILE: a bitstream which is managed by a file system as a single, named entity.
HYDRA (http://projecthydra.org/) is an open source repository software solution.
INGEST: The process by which a digital object or metadata package is absorbed by a different system than the one that produced it.
JPEG (Joint Photographic Experts Group) is the name of the group that developed the standard. JPG is a compression method for images.
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MASTER (copy) is also known as Preservation Master or Archival Master.
METS: A standard for encoding descriptive, administrative, and structural metadata about objects within a digital library, expressed using XML. METS is the national standard for wrapping digital library materials, developed by the Digital Library Federation (DLF) and maintained by the Library of Congress. See the METS web site for more information.
MIGRATION: The transfer of digital objects from one hardware or software configuration to another, or from one generation of computer technology to a subsequent generation. The purpose of migration is to preserve the integrity of digital objects; and to retain the ability for clients to retrieve, display, and use them in the face of constantly changing technology. Migration includes refreshing as a means of digital preservation, however, it is not always possible to make an exact digital copy of a database or other information object and still maintain the compatibility of the object with a new generation of technology.
MODS: An XML schema and data structure and interchange standard, used for the creation of original resource description records (and may also be used as an alternative method for representing MARC data). MODS was developed by the Library of Congress' Network Development and MARC Standards Office. See the MODS web site for more information.
OAIS: A conceptual framework for an archival system dedicated to preserving and maintaining access to digital information over the long term. See the OAIS reference model: PDF.
OCR (Optical Character Recognition), computer software designed to convert images of text (usually captured by a scanner) into machine-editable text
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