D A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T| U| V| W| X| Y| Z| Numerical Listing| DAE (Distributed Automation Edition) An IBM software solution for writing factory-floor applications independent of the distributed data, local-area network protocol or terminal type. DAL (Data Access Language) From Apple Computer Inc., a database interface — itself a superset of Structured Query Language — that enables access to Macs or non-Apple computers. DASD (Direct Access Storage Device) IBM nomenclature for a storage peripheral that can respond directly to random requests for information; usually denotes a disk drive. DASS (Digital Access Signaling System) The original British Telecom (BT) Integrated System Distributed Network signaling developed for single and multiline Integrated Digital Access but used in the BT ISDN pilot service for single line IDA only. Data Dictionary A repository of information about data, such as its meaning, relationships to other data, origin, usage and format. The dictionary assists company management, database administrators, systems analysts and application programmers in effectively planning, controlling and evaluating the collection, storage and use of data. A data dictionary manages data categories such as alias, data elements, data records, data structure, data store, data models, data flows, data relationships, processes, functions, dynamics, size, frequency, resource consumption and other user-defined attributes. Data Integrity Accuracy, validity and consistency of data (according to a set of rules for changing the database). Data Management/Middleware Manages the efficient storage, retrieval, security and integrity of any kind of information. TOP OF PAGE Database Manager IBM’s relational database management system offered as part of OS/2 Extended Edition. Database Partitioning The practice of separating a database into portions that may reside on more than one disk volume or more than one system. DB/DC (Database/Data Communication) This acronym refers to IBM’s collection of transaction managers and database managers, e.g., Customer Information Control System, Information Management System, Database-2 and SQL/DS. DB/File Distribution Management Selective distribution of all or part of a central database to selected remote midrange systems. A facility for predefining the selection criteria and time for distribution should be included. DB2 (Database-2) IBM’s relational database management offering, originally built for Multiple Virtual Storage systems. It uses Structured Query Language as its data manipulation and definition language. IBM announced versions of DB2 for OS/2 and AIX/6000 in 1Q93. DB2 is IBM’s strategic product for general-purpose information storage, including database management. It is a reasonably complete implementation of the relational technology. The introduction of DB2 Version 2 improves many of the previous performance problems, and we expect IBM to continue to enhance the product over time. DB2 was a reconceptualization of IMS, and a revolutionary change from it. The most strategic component/aspect of DB2 is its interface — namely, Structured Query Language. In fact, DB2 is properly viewed as an SQL engine. DBA (Database Administrator) The person responsible for managing data, namely dataset placement, database performance and data recovery and integrity at a physical level. TOP OF PAGE DBLIB (Database Library) The native application programming interface for Sybase’s SQLServer. It began as a custom Sybase call interface. Other vendors, however, implemented DBLIB for a wide variety of client tools and even for other middleware, such as MDI’s Database Gateway. Sybase has since produced an enhanced version, CTLIB, for its new System 10 database management system product generation. DBMS (Database Management System) A software package that enables end users or application programmers to share data. DBMSs are generally also responsible for data integrity, data access control and automated rollback/restart/recovery. A complete software facility for building, maintaining and generating reports from a database. It has evolved along three generic forms: 1) hierarchical DBMS (1960s) — records were organized in a pyramid-like structure, with each record linked to a parent; 2) network DBMS (1970s) — records could have many parents, with embedded pointers indicating the physical location of all related records in a file; and 3) relational DBMS (1980s) — records were conceptually held in tables, similar in concept to a spreadsheet. Relationships between the data entities were kept separate from the data itself. Data manipulation created new tables, called views. DCE (Distributed Computing Environment) DCE is Open Software Foundation’s (OSF’s) partial solution to the problems of interconnectivity in a heterogeneous environment while addressing interoperability, standards and security. The DCE consists of two service sets: fundamental services including naming, timing, threading, security and remote procedure calls (from Digital, HP, MIT and Siemens) and data-sharing services, including a distributed file system and PC support (from Microsoft, Sun and Transarc). DCE integrates remote procedure calls, presentation services, a naming directory, security, threads (sequential flow of control similar to a task), time services (to synchronize clocks in a DCE) and a distributed file system. DCE (Data Communications Equipment) A device that establishes, maintains and terminates a session on a network. Typically a modem that converts signals for transmission. DCF (Document Composition Facility) Program used in Professional Office System for creating text. Also known as SCRIPT/VS. TOP OF PAGE DCS (Distributed Control System) A process control system using computers dispersed throughout a manufacturing facility. DCTE (Data Circuit Terminating Equipment) The equipment installed at the user’s premises that provides all of the functions required to establish, maintain and terminate a connection. It also provides the signal conversion and coding between the data terminal equipment and the line. DDA (Distributed Data Architecture) Groupe Bull’s scheme for data interoperability. DDBMS (Distributed Database Management System) A DBMS that enables end users or application programmers to view a collection of physically separate databases as one logical single-system image. The concept that is most fundamental to DDBMS is location transparency, namely that the user should not be conscious of the actual location of data. DDE (Dynamic Data Exchange) Microsoft specification for exchanging data between Windows applications. DDI (Digital Document Interchange) The Compound Document Architecture-specified format for encoding revisable form text, graphics and image information. DDL (Data Definition Language) A language for describing the data model for a user database, i.e., the names and access paths for the data and how they are interrelated. For some software products, DDL describes the logical, not the physical, data. Other products use it to describe both. TOP OF PAGE DDM (Distributed Data Management) Originally a product for DDM in a record-oriented environment on the System/38, DDM has expanded to play a role in Distributed Relational Database Architecture as the underlying framework for constructing common interfaces for data interchange between systems. Thus, it is not restricted to relational data exchange. A set of IBM-defined services and protocols that provide transparent access to distributed data files. DDM utilizes advanced program-to-program session protocols. DDS (Dataphone Digital Service – AT&T; Digital Data Service – MCI) A private-line digital service offered intra-LATA (Local Access and Transport Area) by local exchange carriers and inter-LATA by AT&T and some other interexchange carriers, with data rates typically at 2.4 Kbps, 4.8 Kbps, 9.6 Kbps and 56 Kbps. De Facto Standards Specifications or styles that have not been approved by vendor-independent standards bodies, but have, nonetheless, become widely accepted by vendors and users. One example is DOS, a personal computer operating system. Debit/Credit Benchmark A discredited performance measurement for on-line transaction processing throughput. The debit/credit transaction, sometimes called ET-1, simulates an automated teller machine function. It has been replaced by TPC-A and TPC-B, defined by the Transaction Processing Performance Council. Decentralized The description for an application that is distributed, but originates with management information systems, has central applications development, and is centrally supported. TOP OF PAGE DECnet Digital Equipment Corp.’s (DEC’s) family of network products based on Ethernet. Supports peer-to-peer processing. DECnet End Node DECnet network interconnect support so that the midrange system can act as an end node in a DEC-supported DECnet network. DECOmni (DEC Open Manufacturing Network Interface) Digital Equipment Corp.’s version of the Open Systems Interconnection Manufacturing Message Service protocol to be used for control-level device communications. DECT (Digital European Cordless Telephone) An interface specification for European digital mobile telephony. An access technology for "distance communications" with voice, data and video services, depending on the network accessed. DECT employs 10 carrier frequencies between 1.88 GHz and 1.9 GHz. Time division multiple access is used to provide 24 time slots on each channel. DECT has 12 slots for transmission and 12 slots for receiving, and can provide 12 simultaneous calls. DECT’s basic data rate is 32 Kbps, but only 75 percent of the bits are used for voice or data. Slots may be combined to achieve flexible data rates from 25 Kbps to 500 Kbps. A maximum data rate of 10 Mbps is possible. The major strength of DECT is its extremely high traffic-handling capacity. DECT is designed to handle 10,000 erlangs per square kilometer (10,000 erlangs represents at least 50,000 users per square kilometer). DECtp Digital Equipment Corp.’s name for its entire on-line transaction processing marketing program. DECwrite Digital Equipment Corp.’s compound document editor. It is based on the editor engine from Frame Technologies. TOP OF PAGE Demand Management The function of recognizing and managing all the demands for products to ensure that the master scheduler is aware of them. It encompasses the activities of forecasting, order entry, order promising, branch warehouse requirements, interplant orders, and service parts requirements. Dependent Demand Demand is considered dependent when it is directly related to or derived from the demand for other items or end products. Such demands are thus calculated and do not have to be forecast. A given inventory item may have both dependent and independent demand at any given time. DES (Data Encryption Standard) A security specification developed by IBM in 1977. Widely used today, it is available at no charge from many on-line bulletin boards and is based on a single key encryption algorithm. If user A wants to send an encrypted file to user B, user A would first encrypt it with a private key (sometimes referred to as a "secret" key). User B would then decrypt the file with an identical private key. The concern with this encryption-only technique is key management. Recipients must prearrange for possession of the appropriate key for decryption to take place. Design Synthesis The set of technological capabilities for modeling, simulating and analyzing product designs. Also known as conceptual design or top-down design. DFDSS (Data Facility Data Set Services) A member of IBM’s Data Facility family of software products. It provides copy, dump-restore and direct access storage device space management functions. DFHSM (Data Facility Hierarchical Storage Manager) A member of IBM’s Data Facility family of software products. It provides automatic space and availability management among a hierarchy of storage devices. DFP (Data Facility Product) Actually named MVS/DFP, it is the MVS component that contains the access methods and handles catalog management. This MVS back-end contains about half of the 10 million lines of code in that operating system and is the property of the General Products Division of IBM. TOP OF PAGE DFS (Distributed File System) A distributed computing environment standard that provides users with a common file system across different operating systems. Thus Windows users can connect to a Unix machine without knowing any Unix operating-system commands. When files are moved, DFS tracks the new location by storing its address in a database. DFS also eases backup difficulties by automating regular backup routines across each cell through a backup server. DFS has not been widely adopted by systems vendors for two reasons. First, it has its origins in the Unix environment, and is designed for Unix servers to communicate with Unix clients. Most commercial users have PC clients running NetWare, and have little use for DFS. Second, all Unix operating systems already have Network File System installed, and the impetus to incorporate another file service is minimal. DFSMS (Data Facility Storage Management Subsystem) The conceptual repackaging of IBM’s Data Facility family of products and Resource Access Control Facility. It is intended to simplify the management and use of external storage resources by providing a device-independent means of requesting services by data set. DFSORT (Data Facility Sort) A member of IBM’s Data Facility family of software products. It provides high-performance rearrangement of data. DHCP (Dynamic Host Configuration Protocol) An Internet Engineering Task Force Transmission Control Protocol/Internet Protocol (TCP/IP) specification for allocating Internet Protocol addresses and other configuration information based on network adapter addresses. It enables address pooling and allocation and simplifies TCP/IP installation and administration. DIA (Document Interchange Architecture) Defined by IBM as a set of services performed by peer communications processes. DIA functions as a set of communication programs — i.e., software that uses communication facilities such as Systems Network Architecture (or others) to carry out functions requested by users, which can be people, application programs or devices. For reasons of compatibility across the product line, IBM intends that DIA use LU 6.2 facilities. DIA function, however, is independent of the logical unit type, and can and does use LU 2 (3270 data stream) or asynchronous facilities. TOP OF PAGE Dial Up The process of, or the equipment or facilities involved in, establishing a temporary connection via the switched network. Differentiate The methods a vendor uses to distinguish a product from the competition by providing unique benefits to users or independent software vendors. Digital Switching The process of establishing and maintaining a connection under stored program control where binary-encoded information is routed between an input and an output port. Generally, a "virtual" through circuit is derived from a series of time slots (time-division multiplexing), which is more efficient than requiring dedicated circuits for the period of time that connections are set up. Digitizers A purely graphical input device — i.e., a computer-aided design/computer-aided manufacturing system digitizer used in computer-aided engineering for converting locations into storable electronic impulses — with a surface on which a location or a point is selected and then automatically converted into a digital X-Y coordinate suitable for transmission to a computer. Direct Digital Control The use of computers for machine and process control by direct interface to sensor, valves and other control devices. Directory Services Middleware that locates the correct and full network address for a mail addressee from a partial name or address. Dirty Forms Paper documents that are bent, folded and mutilated to some degree, making it difficult to scan and recognize. DIS (Data Interpretation System) A marketing-oriented decision support system product co-marketed by IBM and Metaphor. TOP OF PAGE DISA (Direct Inward System Access) This feature allows an outside caller to dial directly into the company telephone system and access all the system’s features and facilities. DISA is typically used for making long distance calls from a remote location using the company’s less expensive long distance lines. Discretionary Security Controls An operating system security rating of C2 or higher based on U.S. Department of Defense trusted computer system evaluation criteria. Disk Mirroring The duplication of disks and controllers so that two access paths exist in case a failure occurs on one of them. DISOSS (Distributed Office Support System) An IBM program product that provides library and distribution services and document translation functions. DISOSS operates only under Customer Information and Control System in the Multiple Virtual Storage (MVS) and Virtual Storage Extended operating systems environments. It provides no interactive user services and requires Personal Services/CICS (PS/CICS) to provide those facilities for terminal users. It also supports IBM’s second-generation products (e.g., 5520 and 8100). It is the interconnect facility for OfficeVision/MVS and the rest of the OfficeVision family. Dispatching The selecting and sequencing of available jobs to be run at individual workstations and the assignment of these jobs to workers. Distributed Control System A series of computer-based devices that operate in conjunction with each other on a variety of applications. TOP OF PAGE Distributed Data Management A form of cooperative processing in which some portion of the database management system executes on two or more nodes. Distributed Database A database whose objects (tables, views, columns and files) reside on more than one system in a network, and can be accessed or updated from any system in the network. Distributed DB — Read Availability of a distributed, location-transparent database facility residing on multiple midrange system nodes whereby location of and access to information are transparently managed by the system rather than by applications at each node. Remote access is at least read-only. Distributed DB — Read/Update Availability of a distributed, location-transparent database facility residing on multiple midrange system nodes whereby location of and access to information are transparently managed by the system rather than by the applications at each node. Remote access is for update as well as read. Distributed Function A form of cooperative processing in which some of the application program logic executes on one node, possibly with a database, and the rest of the application resides on another node, possibly along with presentation services. Distributed Naming/Directory Services Directory facilities available transparently to all midrange systems in the network allowing cross-net resource location and access. Directories can be maintained centrally and independently of each midrange system operation. More than one copy of the main directory at multiple nodes could be used to improve directory access performance. Distributed OLTP Monitor An on-line transaction processing monitor implementation that enables deployment of the application across multiple systems with minimal application programmer involvement or foreknowledge. TOP OF PAGE Distributed Presentation A form of cooperative processing in which some of the presentation handling executes on one node and the rest of the presentation, along with the remainder of the application and the database, executes on another node. Distributed Processing A data processing organizational concept under which computer resources of a company are installed at more than one location with appropriate communication links. Processing is performed at the user’s location, generally on a minicomputer, and under the user’s control and scheduling. This is in contrast to a large, centralized computer system which handles processing for all users. It is also the ability of an application to run on one or more nodes of a multiplatform network. The user need not be aware of the physical location of the data or the application software. The application can operate using cooperative processing, but this condition is not necessary. Distributed Systems Refers to computer systems in multiple locations throughout an organization working in a cooperative fashion, with the system at each location serving the needs of that location but also able to receive information from other systems and supply information to other systems within the network. Distribution Service Middleware that ensures a mail package is delivered to the specified addressee. Divestiture The Justice Department’s legal action against AT&T leading to the terms of the Modified Final Judgment. AT&T agreed to the 1982 Consent Decree, and in 1984 it relinquished ownership and control of its 22 wholly owned local Bell telephone operating companies. DL/1 (Data Language/1) The "language" in which the application programmer specifies requirements to Information Management System/Database Manager (IMS/DB). It also denotes the DOS version of IMS/DB. For some time now, DL/1 has been synonymous with IMS/DB, even for IBM. TOP OF PAGE DLS (Data Link Switching) An IBM-developed technique for carrying systems network architecture and NetBIOS over TCP/IP. DLS "tunnels" or encapsulates SNA traffic utilizing the transport services of TCP/IP. Upon entry into a router-based internet, SNA traffic is placed into TCP segments, which are then sent across the network as IP data grams. Intermediate routers along the session path "see" only standard IP data grams and addresses, with no need to recognize SNA information flowing through them. At the destination router, TCP/IP protocol headers are stripped off, and the original SNA traffic is sent in "native" mode to an SNA network or destination device using SNA addresses. With DLS, the entire TCP session "looks like" a source-route bridged LLC2 connection to SNA products at either end. Other features of DLS support remote synchronous data link control connections without the need to send polling information across the internet. (Besides SNA, DLS can also be used to send "nonroutable" NetBIOS traffic across TCP/IP sessions.) DMA (Direct Memory Access) A means of handling data transfer between memory and a peripheral device that bypasses the central processing unit. DME (Distributed Management Environment) From the Open Software Foundation, DME will result in architectures and services that will simplify systems management applications across multiple platforms. DME includes such tasks as backup/restore, printing services, software installation, software distribution and user management. A more global initiative allows organizations to have a consistent approach to managing their systems. DML (Data Manipulation Language) The language by which an application programmer invokes functions from a database management system product to access and manipulate data. DMPP (Distributed Memory Parallel Processors) Massively Parallel Processing machines without shared memory capabilities, also known as "loosely-coupled." TOP OF PAGE DNIS (Dialed Number Identification Service) DNIS is a feature of 800 and 900 lines. The long distance carrier transmits the DNIS of the incoming call to identify the numbers the person dialed to reach the recipient. Those DNIS digits may received via in-band or out-of-band format, integrated services digital network or data channel, etc. DNS (Distributed Naming Services) A DECnet service that enables a network resource to be named independently of its physical location. Using DNS, a database could be referred to as "SALES," regardless of where it was located or relocated. Document Management An application or middleware that performs data management tasks tailored for typical unstructured documents (including compound documents). It may also manage the flow of documents through their life cycles. Document Representation Standards Internal data streams that can support the transport of text, data, graphics, image and, in the future, voice and video. We believe vendors should develop data streams aligned as closely as possible to the Open Document Architecture specifications. DOMF (Distributed Object Management Facility) Hewlett-Packard’s distributed object management facility, which is based on the Common Object Request Broker Architecture (CORBA) standard from the Object Management Group. DOMF provides a location-transparent object-communication mechanism across heterogeneous networks by using the DCE standard. HP is working with IBM to integrate HP’s DOMF with IBM’s System Object Model (SOM), which would eventually provide users with scalability, portability and interoperability of distributed applications across HP and IBM platforms. TOP OF PAGE DOS/VSE (Disk Operating System/Virtual Storage Extended) The low-end operating system for IBM’s S/370 architecture computers. DOS/VSE typically operates on smaller machines, especially in nonadvanced environments. Double-Byte Character Set Support Support for system and application use of double-byte character sets as required for Far Eastern national language support. DOV (Data Over Voice) A technology that transmits data and voice simultaneously over twisted-pair copper wiring and is used primarily with local Centrex services or special customer premises private branch exchange. Data rates for Centrex operation are 9.6 Kbps and 19.2 Kbps. Download of DB2, IMS, VSAM Data A facility allowing the midrange system to initiate an information download from Database-2, Information Management System or Virtual Storage Access Method data files on System/370 mainframe to a data file or database on the midrange system for local access and processing. Downsizing The process of moving computing work to a smaller computer. DPA (Document Printing Architecture) International Standards Organization standard 10175 that defines print objects, attributes and protocols for submitting print requests across heterogeneous systems. Designed to provide a distributed printing system with high levels of interoperability, robustness, reliability and stability. TOP OF PAGE DPI (Dots Per Inch) A measurement of resolution; e.g., the number of pixels per inch on a cathode-ray tube display. DPN (Data Packet Network) Northern Telecom’s public packet networking product. With DPN, large organizations have the option of expanding their private networks into public networks. This brings two primary benefits. First, external revenue can defray the cost of the organization's telecom infrastructure. Second, the provision of network services to key clients, suppliers and others can be a significant competitive advantage. DPNSS (Digital Private Network Signaling System) A standard which enables private branch exchange from different vendors to be connected with E1 lines and pass calls transparently between each — as if the phones were extensions of the same PBX. This originated in Britain. DQDB (Dual Queue Distributed Bus) The Institute of Electrical and Electronics Engineers (IEEE) 802.6 standard for a metropolitan-area network. DQDB is a very high-speed (150 Mbps), distance-insensitive network that transports both voice and data. It uses a form of asynchronous time-division multiplexing. By watching for empty cells on the buses, it avoids the need to pass token, as in FDDI (fiber distributed data interface). DQDB is the underlying media-access control protocol developed for the IEEE 802.6 MAN standard. DQDB supports data rates of 45 Mbps to 155 Mbps and isochronous circuits up to 1.544 Mbps. DQDB, which was designed for MAN usage, complements emerging ATM networks on the WAN side, as 802.6 uses the same format and cell size as ATM. DR (Distributed Request) One of the four functional elements of IBM’s Systems Application Architecture Distributed Relational Database strategy that systematically executes a single Structured Query Language statement accessing multiple databases. TOP OF PAGE DRAM (Dynamic Random Access Memory) Computer memory chip that requires electronic refresh cycles to preserve data stored for manipulation by logic chips. DRDA (Distributed Relational Database Architecture) IBM’s architecture for enterprisewide data access, announced in July 1990. The architecture is designed to homogenize the way data is defined and accessed across IBM’s different hardware/software platforms, as well as address multilingual coding standards. While explicitly concerned with relational data (by its name), DRDA also attempts to deliver distributed access to pre-relational data, an issue with which IBM continues to struggle. DRM (Distributed Resource Management) An evolving discipline consisting of a set of software, hardware, network tools, procedures and policies for enabling distributed enterprise systems to operate effectively in production. DRM embraces solutions for the daily monitoring, resource planning, system administration, change management, operations, performance and other initiatives that are needed to maintain effective productivity in a distributed networked computing environment. DS-0 (Digital Signal Level 0) A telephony term for a 64-Kbps standard telecommunications signal. DS-1 (Digital Signal Level 1) A telephony term describing the 1.544-Mbps digital signal, or T1 rate. DS-1C (Digital Signal Level 1C) A telephony term describing a 3.152-Mbps digital signal. TOP OF PAGE DS-2 (Digital Signal Level 2) A telephony term describing the 6.132-Mbps digital signal carried on a T2 facility. DS-3 (Digital Signal Level 3) A telephony term describing the 44.7-Mbps digital signal. DS-4 (Digital Signal Level 4) A telephony term describing the 274.2-Mbps digital signal. DSA (Dynamic Server Architecture) From Informix Software, DSA is a parallel, scalable architecture that supports large databases running on massively parallel, loosely coupled, symmetric multiprocessing and uniprocessor computers. DSA is designed to be independent of platforms and transparent to applications. DSOM (Distributed System Object Model) IBM's distributed object technology, which originated on OS/2 2.0 and AIX but will be ported to other operating environments, including Windows. DSOM is a follow-on to System Object Model, an operating-system extension that provides object-oriented programming (OOP) mechanisms such as method dispatching and inheritance to OS/2 2.0 and 2.1. DSOM is a Common Object Request Broker Architecture (CORBA)-compliant system. DSP (Digital Signal Processor) Specialized computer chip optimized for high data rates needed to process digitized waveforms. TOP OF PAGE DSRI (Digital Standard Relational Interface) Digital Equipment Corp.’s proprietary, low-level application programming interface to Rdb. DSS (Decision Support Systems) Systems designed to support the information needs of tactical and strategic decision-making, as opposed to systems responsible for running the business. (Frequently contrasted to on-line transaction processing). A data processing mode emphasizing user friendliness and ad hoc query, reporting and analysis capabilities. This mode is contrasted to on-line transaction processing, which focuses on low-cost, fast-response, predictably structured applications. DSU (Data Service Unit) A device designed to connect data terminal equipment to a digital phone line to allow digital communications. A DSU is the digital equivalent of a modem. DTE (Data Terminal Equipment) The part of a data station that serves as a data source, data sink or both, and provides for the data communication control function according to protocols. DTIF (Digital Table Interchange Format) The Compound Document Architecture-specified format used for the storage and interchange of documents that contain data tables, formulas and spreadsheets. DTP (Distributed Transaction Processing) X/Open’s on-line transaction processing initiative to foster open system connectivity at an applications level. Standards include XA, XA+, TX and CRM. Dumb Terminal A terminal not performing local processing of entered information; serves only as an input/output device for an attached or network-linked processor. TOP OF PAGE DUOW (Distributed Unit of Work) Part of IBM’s classification of Distributed Database capabilities; a self-contained set of Structured Query Language (SQL) requests accessing data that may be situated at multiple physical locations. Each SQL request can access only one system. One of the four functional elements of IBM’s Systems Application Architecture Distributed Relational Database Strategy that coordinates the systematic execution of multiple SQL statements accessing multiple databases. DXI (Data Exchange Interface) A first-generation, frame-oriented, external asynchronous transfer mode (ATM) interface standard supporting ATM adaptation layer 3/4 and 5, but not constant bit rate traffic. DXT (Data Extract) An IBM-licensed program designed for use with user-written exits to support data extraction from a variety of Multiple Virtual Storage files. Originally designed to support extraction of data from Information Management System/Database Manager and Virtual Storage Access Method (into DB2 and SQL/DS), DXT now supports extraction from DB2 and SQL/DS, and with version 2.3 from third-party database management system products. Version 2.4 enables extraction from Digital Equipment Corp. VAX/VMS data sources. Dyadic A dyadic multiprocessor design is a term IBM introduced with the 3081. Multiple Virtual Storage sees a dyadic processor as two processors running as one. TOP OF PAGE Dynamic Adaptive Routing Automatic selection and use of alternative communications paths among two or more midrange systems of the same supplier in the event of a congested, faulty, or downed circuit within the preferred data path. Dynamic Database Restructuring The ability to change the relational database structure, table capacities and security without unloading and reloading the database. TOP OF PAGE Dynamic Hardware Reconfiguration The ability to add or delete midrange system hardware components and modify operating system hardware configuration tables by operator control without turning power off and reinitializing the operating system. Comments? Questions? Entire contents Copyright © 1997, 1998 by Gartner Group, Inc. All rights reserved. Reproduction of this publication in any form without prior written permission is forbidden. Please read the guidelines for customer use of GartnerGroup intellecual property.