Information Management


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D

There are 410 entries in the glossary.
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Term Definition
D ListStorage products. SCSI Term. This list shows the positions of defects as specified by the INIT using the FORMAT UNIT command during disk initialisation.
 
DaemonA term mainly used regarding UNIX processes. A daemon (or demon) is a process that starts and does nothing until it is called by another process or a certain condition is met. This is similar to a TSR program.
 
Data CentreA space containing one or more production servers, minicomputers, or mainframe computers requiring enhanced access control and other physical security features. Rooms containing development or test servers and computers require less security than is required for a data centre.
 
Data Encryption Standard (DES)An encryption method developed by IBM in 1977. It uses a private 56-bit key that is applied to each 64- bit block of data. The sender and receiver must each know the private key. Anything encrypted by DES encryption has 72,000,000,000,000,000 (or 72 quadrillion) possible keys. DES encryption has been broken, but it took over 14,000 computers operating in succession to crank through codes until the proper key was found. See also Triple DES encryption.
 
DE
Storage products. Disk enclosure, container of five sub-assemblies :


  • Fixed disks
  • Spindle with integrated motor
  • Actuator
  • Heads
  • Filtering system

Protection of the internal components from environmental contaminants requires that the DE be sealed at the source of manufacture and must not be opened. DE is sometimes referred to as the head/disk assembly (HAD)

 
Dedicated ServoStorage products. Positioning method where servo information is written on one disk surface only. This position information is read and evaluated permanently. The linear voice coil actuator and thus the read/write head is tracked precisely.
 
DefectStorage products. Some irregularity in a medium which disturbs its ability to carry recorded data. Defects in an optical disk include bumps, depressions, dirt, missing sensitive material, etc. Because of the high density of optical recording, even micrometer size defects are important.
 
Defect (Pre-Write)Storage products. 1. - An area of the recording zone which when read prior to any recording, yields an unexpected single amplitude. 2. - The ratio of the sum of the time intervals from the beginning to the end of drop-ins on the disk to the total available recording time on the disk.
 
Defect DistributionStorage products. The geographic distribution of errors on an optical disk measured along its tracks and radially across its tracks in terms of the occurrence of successive n-bit errors. This concerns the media in both an unrecorded and recorded state and does not address focus or tracking servo defects.
 
Defect ManagementStorage products. A strategy whereby defective media areas (e.g., sectors) that cannot be written due to hard (uncorrectable) errors, are automatically assigned to alternative areas which do not contain hard errors. The strategy generally includes guidelines for disk rewrite and disk retirement. Disk retirement is retention of a disk which can be read but not written.
 
Defect Rate, InitialOptical. Average raw bit error rate of an optical disk when writing and reading user data for the first time.
 
DescreeningScanners. Removal of halftone dot patterns during or after scanning printed matter by defocusing the image. This avoids moire patterning and colour shifts during subsequent halftone reprinting.
 
DescriptionInformation about the type, content and date of documents.
 
DestructionProcess of eliminating or deleting records, beyond any possible reconstruction.
 
Digital CertificateAn electronic means of certifying that a message, file, or encryption key has been sent by the person or machine claiming to have originated the message, file or key. A digital certificate issued by a trusted certificate authority provides a high degree of assurance that the data originates from the claimed originator.
 
Digital SignatureA means of 'signing' a document by performing a mathematical calculation involving the document and a private encryption key. The signature can be verified on receipt by performing a different mathematical calculation on the digital signature with the user's public encryption key.
 
Direct Read After Write (DRAW)Storage products. A process in which data is read for verification immediately after being written.
 
Direct Read During Write (DRDW)Storage products. Describes a method of error checking data on an optical disk in which data is written and verified during the same disk rotation. Refers to the ability to read the information during the writing (recording) process.
 
DisasterA sudden and negative event that damages some or all archival holdings and interferes with normal services and programs of the archives: may also harm organisation's property and interfere with business activities.
 
DisposalDecision about the final fate of records, either destruction or permanent preservation.
 
DispositionRange of processes associated with implementing records retention, destruction or transfer decisions, which are documented in disposition authorities or other instruments.
 
Distributed Enterprise RepositoryContent can be distributed across multiple repositories with seamless user access.
 
Dither MatrixScanners. Mask that generates psuedo randon numbers used by the dithering process to represent pseudo continous tone, 4x4 and 8x8 are common matrix sizes
 
DitheringScanners. The process of specifying colour to adjacent pixels in order simulate a third colour in a bitmapped image. This technique is used when a full range of colours is not available.
 
DLC Protocol (Data Link Control).General computing. A set of rules used by two nodes on a data link to accomplish an orderly exchange of information.
 
DocumentStructured units of recorded information, published or unpublished, in hard copy or electronic form, and managed as discrete units in information systems
 
Document setA group of complete related items to serve a given business need.
 
Dot GainPrinters / Scanners. A printing defect in which dots print larger than intended, causing darker colours or tones. Dot gain measures the increase in halftone dot values that occur during the offset printing production process. Total dot gain is measured as the difference in apparent dot size between the final printed product and the original film. Dot gain occurs as the result of both mechanical and optical influences on the original dot size
 
DPIDots per inch. A measure of how detailed an images is.
 
Dropout ColourScanners. A colour used in document which will/should be removed from the final Scanned image. A scanner with a green lamp will tend to drop green colours, a scanner with a red lamp will drop red. So a data collection form may be printed in red such that the forms background is droppped out leaving just user entered data in the scanned image
 
DTDAbbreviation of document type definition: a description of the structure of types of document in SGML and XML; it defines how the constituent text and mark-up –(tags) should be parsed by an application which processes such a document. However, e-GIF mandates the use of XML schema rather than DTD for this purpose.
 
DuplexScanners. Double sided.
 
Dynamic ThresholdingScanners. A process by which the threshold for binarization is calculated based on the density and shade level of the image or background being scanned
 


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Glossary V1.8
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