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This site contains terms and definitions from many IBM software and hardware products as well as general computing terms.


See universal port.


  1. See user agent.
  2. See unnumbered acknowledgment.

See universal access authority.

See user attribute data set.

See Universal Asynchronous Receiver/Transmitter.

See unsigned binary number.

See user block.

See unified buffer manager.

See user buffer pool.

See undercover agent.

See unit control block.

See User Centered Design.

See utility control facility.

See Unified Change Management.


  1. See Uniform Communication Standard.
  2. See universal character set.


  1. A 2-byte (16-bit) encoding scheme based on ISO/IEC specification 10646-1. UCS-2 defines three levels of implementation: Level 1-No combining of encoded elements allowed; Level 2-Combining of encoded elements is allowed only for Thai, Indic, Hebrew, and Arabic; Level 3-Any combination of encoded elements are allowed.
  2. Universal Character Set, coded in 2 octets, which means that each character is represented by 16 bits. UCS-2 is a subset of UTF-16. See also UTF-16, UTF-8.

See user-defined aggregate.


  1. See user-defined cast.
  2. See user-defined character.

See Universal Description, Discovery, and Integration.

UDDI Business Registry
A collection of peer directories that contain information about businesses and services.

UDDI node
A set of web services that supports at least one of the Universal Description, Discovery, and Integration (UDDI) APIs. A UDDI node consists of one or more instances of a UDDI application running in an application server or a cluster of application servers with an instance of the UDDI database.

UDDI node initialization
The process by which values are set in the Universal Description, Discovery, and Integration (UDDI) database and the behavior of the UDDI node is established.

UDDI node state
A description of the current status of the Universal Description, Discovery, and Integration (UDDI) node.

UDDI policy
A statement of the required and expected behavior of a Universal Description, Discovery, and Integration (UDDI) registry that is specified through policy values that are defined in the UDDI specification.

UDDI property
A characteristic or attribute that controls the behavior of a Universal Description, Discovery, and Integration (UDDI) node.

UDDI registry
A distributed registry of businesses and their service descriptions that adheres to the Universal Description, Discovery, and Integration (UDDI) standard for managing the discovery of web services. UDDI registries come in two forms, public and private, both of which are implemented in a common XML format.

See user-defined data stream.


  1. See user-defined function.
  2. See user-defined field.
  3. See Universal Disk Format.

UDF file system
An implementation of a writable local file system that can be stored as a read-only file system on DVD-ROM media or as a read-write file system on DVD-RAM media.

UDFS disk pool
An independent disk pool that contains only user-defined file systems. It cannot be a member of a disk pool group unless it is converted to a primary or secondary disk pool.

See user-defined log.

UDL entry
An individual entry in a user-defined log (UDL) that stores custom content for categories in hierarchies or items in catalogs. See also user-defined log.

See User Datagram Protocol.

See user-defined routine.

See user-defined statistics.

See user dynamic storage area.


  1. See user-defined type.
  2. See user-defined data type.

See Unified Extensible Firmware Interface.

See user entry procedure.

See UNIX file system.

See user interface.

See user interface block.

UI component
Any discrete, functional part of a graphical user interface.


  1. See user identification.
  2. See user identifier.
  3. See unique identifier.
  4. See user number.

See user identification number.

UI framework
A set of user interface components and standards that together can be used to create a graphical user interface.

UI locale
A locale that governs all of the user interface of a particular program. See also data locale.

See user interface manager.

See Unstructured Information Management Architecture.

See UIMA Asynchronous Scaleout.

UIMA Asynchronous Scaleout (UIMA AS)
An architecture that provides for scaling out annotators by creating multiple instances for each annotator class. Each instance runs in its own thread. It is also possible in UIMA AS to spread the processing elements out across servers, which then communicate between each other using "messages" – through the use of a message queuing middleware like Apache ActiveMQ. In the case of UIMA AS, the messages are individual CASes.

UIMA descriptor
A UIMA configuration file for a primitive UIMA analysis engine or a configuration for an aggregate set of other descriptors.

UIMA framework
See Unstructured Information Management Architecture framework.

See UIMA software development kit.

UIMA software development kit (UIMA SDK)
A software development kit that includes an all-Java implementation of the UIMA framework for the implementation, description, composition, and deployment of UIMA components and applications.

UIM tag language
A System i language supported by the user interface manager to define panels, menus, and help items.

U interface
In the reference model for the integrated services digital network (ISDN), the interface that includes the transmission line between the network terminator 1 (NT1) and the line transmission termination (LT).

UI part
An EGL declaration that is used for data presentation. The types of UI parts are forms, form groups, and UI records.

UI record
In EGL, a data structure that makes communication possible between an action program and a specific web page. This type of record is used to migrate VisualAge Generator Web transactions.

See user information source.

See usage license charge.

See upper-layer timeout value.

ultimate ancestor
An ancestor member that resides at the top level of a hierarchy.

ultimate consumer
The target for data in an input and output operation. An ultimate consumer can be a file, a device, or an array of bytes in memory.

ultimate producer
The source for data in an input and output operation. An ultimate producer can be a file, a device, or an array of bytes in memory.

Ultimedia Business Conferencing
An IBM licensed program that provides a solution for desktop business conferencing. Ultimedia Business Conferencing is a cooperative processing application that manages the conference from scheduling to completion.

ultra-light mode
A version of the SmartCloud Notes web client that can be used with mobile devices and that is also accessible.

An enhanced Small Computer System Interface (SCSI).

The pattern of default permissions that are set automatically when a file is created. These defaults can be changed by including an appropriate umask command in the system profile.

See Universal Message Format.

UMF document
The collection of Universal Message Format (UMF) segments that structure the data. See also UMF file.

UMF element
An XML tag and value that defines the data within a Universal Message Format (UMF) segment of a UMF document.

UMF file
A file that contains one or more Universal Message Format (UMF) documents. See also UMF document.

UMF message
See UMF document.

UMF record
The entire data record that defines the data being ingested in the pipeline. For example, Passenger name record or Arrest record.

UMF record segment
See UMF segment.

UMF segment
The part of a Universal Message Format (UMF) document that structures the data for the data source. See also DQM rule.

See Unified Modeling Language.

UML logical architecture
An architecture that is an interpretation of what that architecture should look like and is independent of the overall technology to be implemented. It is intended to be an abstraction of it.

See user-maintained data table.

unacknowledged service
In communications, a data transfer service that does not provide for an acknowledgment from data receiver to data sender that the data was received. An active data link connection does not need to be established between receiver and sender before sending the data. See also acknowledged service.

unary expression
An expression that contains one operand.

unary operator

  1. In COBOL, a plus sign (+) or a minus sign (-) that precedes a variable or a left parenthesis in an arithmetic expression, which has the effect of multiplying the expression by +1 or -1, respectively.
  2. An operator that represents an operation on one operand. See also binary operator.
  3. A group of mathematical indicators (+,-,*,/) that define how roll-ups are executed in a database outline.

unassigned work
Work that does not require completion by a specific participant but can instead be completed by any one of a number of users or by an automated program. At run time, unassigned work is routed to a specified work queue; a user or program with access to that work queue can open and complete the work contained within.

unassociated volume
A volume that is not associated with a consistency group. See also consistency group, volume.

unattended installation
An installation that does not require any user interaction. See also silent installation.

unattended mode
In Operations Console, a state of the system when the local controlling system can automatically grant access to a remote request for control of the System i system as long as the local controlling system does not have control at the time of the request.

unattended mode IPL
An IPL mode that automatically loads the operating system without any user interaction. See also attended mode IPL.

unattended operation
An operation not requiring a human operator to be at the device. See also attended operation.

unattended setup
Operating system installation on a target, using original installation files and parameters contained in a script defined on the OS deployment server. See also clone.

To remove the last template that was augmented to a profile. A profile must be unaugmented before it is deleted. See also augment.

unauthorized access
Gaining access to resources within a computer system without permission.

unbalanced hierarchy
A hierarchy that has leaf nodes at more than one level. The parent of every member comes from the level immediately above.

In SNA, to deactivate a session between logical units.

See unbind session.

UNBIND command
In SNA, a command used to reset the protocols for a session. See also BIND command.

unbind session (UNBIND)
A request to deactivate a session between two logical units (LUs).

In an Enterprise Systems Connection Director, pertaining to the attribute that, when set, establishes communications capability for a specific port.

unblocked signal
In POSIX, a condition that allows a signal-handling action associated with a signal to be performed. See also blocked signal.


  1. Pertaining to a model for which the objective function can be optimized without limit.
  2. Pertaining to a variable for which one or both of its bounds is infinite.

unbounded-box font
A font designed to use unbounded character boxes. See also bounded-box font.

unbounded-box format
An organization of character graphics and information used by AFP programs for printers such as the IBM 3800 Printing Subsystem Model 3. Character boxes containing each character graphic do require some character positioning information in the form of white space in the character boxes. In addition, a separate character set is required for each combination of character rotation and text orientation. Fonts in unbounded-box format usually require more storage than fonts in bounded-box format. See also bounded-box format.

unbounded character box
A character box that can have blank space on any sides of the character shape. See also bounded character box.

unbounded loop
A loop in which the maximum number of times that the loop can be iterated is unknown. This means that there is no upper limit to the number of times the questions in the loop can be asked. An unbounded loop cannot be defined as an expanded loop, and therefore grid tables cannot be created from an unbounded loop.

unbound set
The set of all possible types of data that might be listed last in a group.

To convert an object type to a primitive type. See also autobox, auto-unboxing, boxing.

unbuffered disk I/O
Disk I/O that is controlled directly by the database server instead of the operating system. This direct control helps improve performance and reliability for updates to data. Unbuffered I/O is supported by character-special files on UNIX and by both unbuffered files and the raw disk interface on Windows. See also buffered disk I/O.

See Universal Naming Convention.

uncapped partition
A logical partition that uses a shared processor pool whose assigned current processing capacity might be exceeded when the shared processor pool has any unused processing power. The value assigned to the uncapped partition determines the percentage of unused processing power that a logical partition receives when more than one uncapped partition is contending for the processing power in the shared processor pool.

uncapped weight
A number in the range of 0 through 255 that can be set for each logical partition in the shared processor pool. Based on these values, any available unused capacity is distributed to contending logical partitions in proportion to the normalized values of their uncapped weight.

uncommitted read (UR)
An isolation level under which a query in a transaction can read any rows, even if there are uncommitted changes to those rows made by statements in other transactions. The UR isolation level is upgraded to CS when data is being modified. See also committed read, cursor stability, isolation level, read stability, repeatable read.

unconditional branch
A branch that is taken every time it is encountered.

unconditional breakpoint
A breakpoint where processing is suspended during every run. See also conditional breakpoint.


  1. To take a device from the available (configured) state to the defined state by running the unconfigure method for a device. This action is reflected in the device status field of the Customized Devices Object Class.
  2. To take out of use by the current computer system.

unconfigured mode
A mode in which I/O operations cannot be performed. See also access mode, image mode, managed mode.

unconfirmed instance
An instance of an installed software product that has not been explicitly assigned to any license. See also software product.

unconfirmed service
In OSI, a service that does not indicate to the sender whether or not data or control information was properly received. An unconfirmed service involves only request and indication service primitives. See also confirmed service.

unconnected state
A state of a trusted connection in which no user is associated with the connection and no data can be sent or received until the client switches the trusted context user ID.

uncontrolled flow
A flow that proceeds without dependencies or conditional expressions. Typically, an uncontrolled flow is a sequence flow between two activities that do not have a conditional indicator (mini-diamond) or an intervening gateway.

The process of putting a solution back in terms of the original formulation of a problem so that a customer can recognize it. See also crush.


  1. To take a device instance out of the system by running the undefine method for the device. This action purges all of the device information that is in the Customized Database.
  2. To cause a command to no longer recognized by the current computer system.

undefined behavior
Referring to a program or function that might produce erroneous results without warning because of its use of an indeterminate value, or because of erroneous program constructs or erroneous data. See also implementation-defined.

To restore an item to the database.

undelivered message queue
See dead-letter queue.

To remove files or uninstall software from an operational environment. For example, in a policy-enabled system, policies are undeployed from the autonomic managers, making them no longer available for use in that operational environment. See also deploy.

undercover agent (UCA)
An agent that is attached to a message event in a business process definition (BPD) and that calls a service to handle the event. For example, when a message event is received from an external system, a UCA is needed to invoke the appropriate service in response to the message.

A condition that occurs when the result of an operation is less than the smallest nonzero number that is allowed.

underlying connection
The representation of lower-layer connectivity that is used by higher-layer connectivity. For example, the physical connection that transports data between two IP hosts is an underlying connection.

underlying view
The view on which another view is directly or indirectly defined.

In architecture, a mixing rule in which the intersection of part of a new presentation space Pnew with part of an existing presentation space Pexisting keeps the color attribute of Pexisting. See also blend, overpaint.


  1. Loss of data caused by the inability of a transmitting device or channel to provide data to the communications control logic at a rate that is fast enough for the attached data link or loop.
  2. To run out of audio data to play, resulting in voice or music being audibly broken up or cut off.

A situation in which shared file system is not scanned at all, or some of its parts are not scanned. See also overscanning.


  1. To place a line under one or more characters; to underline.
  2. A line printed under a character or along the lower edge of the space normally occupied by a character.

underscore character
A character used in each position of an entry field to indicate its length. This indicator of entry field length is used on display devices that do not have the underscore attribute.


  1. In a data entry database, a state that occurs when no changes have been committed in the database. The changes are still in main storage and are backed out from there.
  2. To recover the last edit that has taken place.
  3. A state of a unit of recovery that indicates that the changes that the unit of recovery made to recoverable DB2 resources must be backed out.

undoable mode
In software distribution, a mode of operation in which committed actions can be rolled back because a backup copy was saved.

undo/redo record
A log record used in recovery. The redo part of the record describes a change to be made to a WebSphere MQ object. The undo part describes how to back out the change if the work is not committed.

To make an address space unknown to MVS. See also dub.

See deduplication.

unduplicate match
See one-source matching.

See United Nations Electronic Data Interchange for Administration, Commerce and Transport.

In an expression, referring to a character that is not preceded by an escape sequence and is therefore interpreted as a control character.

unfiled document
A document that is not contained in any folder. Users can search for unfiled documents and file them in folders.

To unsubscribe from someone's profile in order to block their activities from one's profile. See also follow.


  1. Pertaining to something that is not defined, organized, or arranged in a required manner. See also field-formatted.
  2. In VTAM, pertaining to commands (such as LOGON or LOGOFF) entered by a user and sent by a logical unit in character form. The character-coded command must be in the syntax defined in the user's unformatted system services definition table. See also converted command, field-formatted.

unformatted event table
A table that is used to store event monitor data in its original binary format, not in a readable format. See also event monitor.

unformatted file
A file that is arranged without such characteristics as a certain number of characters and lines per page, line spacing, and headings. See also formatted file.

unformatted mode
In document formatting, the state in which each input line is processed and printed without formatting. Other SCRIPT/VS control words remain in effect and are recognized.

unformatted print data
Data that is not formatted for printing. A page definition can contain controls that map unformatted print data to its output format.

unformatted print records
Traditional line data made up of fields of data that have not been formatted into print lines. PSF uses a page definition to format these records for printing on page printers.

unformatted system service (USS)
A communications function that translates a character-coded command, such as a LOGON or LOGOFF command, into a field-formatted command for processing by formatted system services. See also field-formatted, formatted system service.

To sever a relationship with someone on a social networking site See also friend.

unhandled condition
A condition that is not handled by any condition handler for any stack frame in the call chain. See also handled condition.

See user-to-network interface.

Transmission of data to a single destination. See also broadcast, MCAST, multicast.

A character encoding standard that supports the interchange, processing, and display of text that is written in the common languages around the world, plus many classical and historical texts. See also multibyte character set.

Unicode-based white space segmentation
A method of tokenization that uses Unicode character properties to distinguish between token and separator characters.

Unicode-enabled file space
A file space with a name that follows the Unicode standard and is compatible with any locale on multilingual workstations.

Unicode Inc.
A consortium chartered to maintain and develop the Unicode standard.

See universal ID.

unidentified user
A user of the i5/OS licensed program who uses the services of i5/OS but who is not automatically reported on by the license management function of i5/OS. An example of an unidentified user is one who accesses a System i system through a gateway server that is not a System i system.

unidirectional printing
A printing method in which the print head on the printer prints only while it moves in one direction, instead of also printing while it moves in the opposite direction. This method of printing usually produces higher-quality print output.

unidirectional replication
In Q replication, a configuration in which changes that occur in a source table are replicated over WebSphere MQ queues to a target table or are passed to a procedure to manipulate the data. Changes that occur in a target table are not replicated back to a source table.

UNID table
A table that maps a note's UNID to its note ID, which, in turn, can be mapped through the database's RRV table to the note's position within the database file.

Unification Precirion Affini (UNIPREA)
The former name of the UNIficazione Information Technology (UNINFO). See also UNIficazione Information Technology.

UNIficazione Information Technology (UNINFO)
The Italian national standards body that develops national standards and co-operates in defining international standards for information technology. See also Unification Precirion Affini.

unified buffer manager (UBM)
The component of the Notes storage facility that caches information about open databases.

Unified Change Management (UCM)
A process for organizing software development teams and their work products. Members of a project team use activities and components to organize their work.

Unified Extensible Firmware Interface (UEFI)
A specification that details the interface between the operating system and the platform firmware at boot time. It is not specific to any processor architecture.

unified messaging
A messaging system in which a single copy of a message is stored and accessed by multiple applications (for example, voice mail and email). See also integrated messaging.

Unified Modeling Language (UML)
A standard notation for the modeling of real-world objects as a first step in developing an object-oriented design methodology.

Unified Resource Manager (URM)
Licensed internal code (LIC), also known as firmware, that is part of the Hardware Management Console. The Unified Resource Manager provides energy monitoring and management, goal-oriented policy management, increased security, virtual networking, and data management for the physical and logical resources of a given ensemble.

A uniform classification system that is used to organize preliminary construction information into a standard order or sequence on the basis of function elements. See also function element.

uniform baseline offset
The distance from the top left corner of a character box to the picture element (pel) position that appears to rest on the baseline. This value, which is coded in the FNO structured field, is the same for all the characters in a font.

Uniform Communication Standard (UCS)
The EDI standard used in the grocery industry.

uniformly spaced font
A font in which the character increment for each graphic character is the same. See also proportionally spaced font.

Uniform Resource Identifier (URI)

  1. A unique address that is used to identify content on the web, such as a page of text, a video or sound clip, a still or animated image, or a program. The most common form of URI is the web page address, which is a particular form or subset of URI called a Uniform Resource Locator (URL). A URI typically describes how to access the resource, the computer that contains the resource, and the name of the resource (a file name) on the computer. See also Uniform Resource Name.
  2. A compact string of characters for identifying an abstract or physical resource.

Uniform Resource Indicator

Uniform Resource Locator (URL)
The unique address of an information resource that is accessible in a network such as the Internet. The URL includes the abbreviated name of the protocol used to access the information resource and the information used by the protocol to locate the information resource.

Uniform Resource Name (URN)
A name that uniquely identifies a web service to a client. See also Uniform Resource Identifier.

Uniform Symbol Specification (USS)
A series of bar code symbology specifications published by AIM; included are USS-Interleaved 2 of 5, USS-39, USS-93, USS-Codabar, and USS-128.

See UNIficazione Information Technology.

uninterpreted name
In SNA, a character string that a system services control point (SSCP) can convert into the network name of a logical unit (LU). Typically, an uninterpreted name is used in a logon or Initiate request from a secondary logical unit (SLU) to identify the primary logical unit (PLU) with which the session is requested. See also network name.

uninterruptible power supply (UPS)
A source of power from a battery installed between the commercial power and the system that keeps the system running, if a commercial power failure occurs, until it can complete an orderly end to system processing.


  1. A variable that can hold any one of several data types, one data type at a time.
  2. An SQL operation that combines the results of two select statements. Unions are often used to merge lists of values that are obtained from several tables.

union set
See stacked set.

union tag
An identifier that names a union data type.

See Unification Precirion Affini.

uniprocessor (UP)

  1. A system containing a single processor. The phrase "comparable uniprocessor" means a system designed to have only a single processor, with the same CPU-clock speed and cache capacity as the SMP system being discussed, running a uniprocessor version of the operating system.
  2. A processor complex that has one central processor.

unique constraint

  1. The rule that no two values in a primary key or key of a unique index can be the same. See also constraint.
  2. A rule that specifies that the values of no two attributes should be the same.
  3. In Informix, a descriptor that is assigned to each column in a table, function argument, or function return type that indicates the type of data that can be held.

unique device
The initial instance of Presence Zones capturing device information.

unique file
A Virtual Storage Access Method (VSAM) file that occupies a data space of its own. The data space is defined at the same time as the file and cannot contain any other file. See also suballocated file.

unique identifier (UID)
An identifier that is assigned to storage-system logical units when they are created. It is used to identify the logical unit regardless of the logical unit number (LUN), the status of the logical unit, or whether alternate paths exist to the same device. Typically, a UID is used only once.

unique index
An index that ensures that no identical key values are stored in a column or a set of columns in a table.

unique key

  1. A key that is constrained so that no two of its values are equal. See also constraint, foreign key, primary key.
  2. A field or set of fields in a database file that must be unique, ascending, and cannot contain a null value. A unique key can become a parent key.


  1. A designation for a level that indicates that each category in that level can be identified by its source value alone, without reference to its ancestors. The user must specify that the data is unique when a level is the convergence level for multiple drill-down paths or when the model contains multiple data sources. For example, employee IDs are unique source values, employee names are not.
  2. In information analysis, a measure of the value occurring exactly once in the table data.

unique product
A product that is uniquely identified to the i5/OS operating system by a product identifier (product ID) and version, release, and modification identifiers (Vx, Rx, Mx).

unique weight
Sort sequence weighting scheme which assigns a different weight to each case and accent variation of characters. See also shared weight, weight.

unique-weight sort sequence
A sort sequence in which each graphic character in the sequence has a weight different from the weight of every other graphic character in the sequence.


  1. The length of measurement: USA, metric or user-defined.
  2. In FORTRAN, a means of referring to a file to use input/output statements. A unit can be connected or not connected to a file. If connected, it refers to the file. The connection is symmetric; that is, if a unit is connected to a file, the file is connected to the unit.
  3. A quantity that is used as a standard of measurement. For example, in XBRL, the unit km/s (kilometers per second) contains two measures: kilometers and seconds.
  4. The defined space within disk units that is addressed by the system.
  5. A mechanical, electrical, or electronic piece of equipment for a special purpose.

unit address

  1. The identifier for a logical subsystem and the logical device within the subsystem.
  2. In mainframe computing, the address associated with a device on a given control unit. On ESCON or FICON interfaces, the unit address is the same as the device address. On OEMI interfaces, the unit address specifies a control unit and device pair on the interface.
  3. The address of a particular device, specified at the time a system is installed.

unit base
In architecture, a one-byte code that represents the length of the measurement base. For example, H'00' might specify that the measurement base is 10 inches.

unit control block (UCB)
A control block in common storage that describes the characteristics of a particular I/O device on the operating system. See also actual UCB, captured UCB.

United Nations Electronic Data Interchange for Administration, Commerce and Transport (UN/EDIFACT)
See Electronic Data Interchange For Administration, Commerce and Transport.

United Nations Standard Products and Services Classification (UNSPSC)
An open global standard for classifying products and services based on common function, purpose, and task.

unit name
See device name.

unit number
The unique identifier of a storage unit within a disk unit or a disk unit subsystem configured on the system.

unit of compilation
In VS COBOL II, a section of source input from which the compiler produces a single object program. A unit of compilation can consist of a containing program and other programs nested within it.

unit of measure (UOM)
A standardized unit that is used to measure a specified property of something.

unit of recovery

  1. A recoverable sequence of operations within a single resource manager, such as an instance of DB2 for z/OS. See also unit of work, unprotected logical unit of work.
  2. A defined package of work to be performed by the Resource Recovery Services (RRS).
  3. A sequence of operations within a unit of work between sync points.

unit of recovery identifier (URID)
Persistent token used by Resource Recovery Services (RRS) to identify a transaction.

unit of reorganization
For HALDB online reorganization (HALDB OLR), the database records that are reorganized within one commit boundary

unit of work (UOW)

  1. A recoverable sequence of operations within an application process. At any time, an application process is a single UOW, but the life of an application process can involve many UOWs as a result of commit or rollback operations. In a multisite update operation, a single UOW can include several units of recovery. See also multisite update, remote unit of work, unit of recovery.
  2. In advanced program-to-program communications, the amount of processing that is started directly or indirectly by a program on the source system.
  3. A recoverable sequence of operations performed by an application between two points of consistency. A unit of work begins when a transaction starts or at a user-requested sync point. It ends either at a user-requested sync point or at the end of a transaction.

unit of work boundary
The point in time when a connection disassociates itself from its current transaction. The following events cause a unit of work boundary to be ended: a commit, a rollback, an XA end (success), an XA commit, or an XA rollback.

unit-of-work identifier
In advanced program-to-program communications, a unique label assigned to the unit of work. The ID is established when the program on the source system is started and is associated with each job started by that source system on the target system. The unit-of-work identifier provides a beginning-to-end audit trail within an APPC network.

unit price
The price for a product sold on the basis of cost per unit of measure.

unit reference code

  1. The last 4 characters of the SRC.
  2. A group of numbers displayed on the console or control panel that identifies failing parts, system or device states, or system or device status conditions.

unit space
The minimum amount of additional spacing acceptable for purposes of horizontal justification, as specified by the font designer.

unit test
A test that determines the usability of units of source code.

universal access authority (UACC)
In RACF, the default access authority that applies to a resource if the user or group is not specifically permitted access to the resource.

Universal Asynchronous Receiver/Transmitter (UART)
An electronic circuit that transmits and receives data through a serial port.

universal character set (UCS)

  1. The ISO standard that allows all data to be represented as 2 bytes (UCS-2) or 4 bytes (UCS-4). Encoding in the UCS-2 form can accommodate the necessary characters for most of the written languages in the world.
  2. A printer feature that permits the use of a variety of character arrays.

Universal Connection
In System i, a program that allows customers to get personalized electronic support by connecting directly to IBM support services.

Universal Description, Discovery, and Integration (UDDI)
A set of standards-based specifications that enables companies and applications to quickly and easily find and use web services over the Internet. See also web service.

Universal Disk Format (UDF)
A writable file system format designed to interchange data. UDF is a subset of ISO/IEC 13346 defined by the Optical Storage Technology Association (OSTA).

universal group
A user group which allows an unlimited number of users to be connected with USE authority.

universal ID (UNID)
A unique 16-byte value that is assigned to a note when the note is first created. UNIDs are used when replicating database notes and when replacing or refreshing database design notes.

universal image
A cloned system profile that has been prepared with all drivers for disk types and hardware abstraction layer variants encountered in the pool of targets to be deployed.

universal integration hub
A unified page presentation architecture that enables site designers to create web portal pages by using various components, including HTML and web content, feeds, portlets, iWidgets, and elements that are derived from frameworks such as Adobe Flex.

Universally Unique Identifier (UUID)
The 128-bit numeric identifier that is used to ensure that two components do not have the same identifier. See also globally unique identifier, vendor ID.

Universal Message Format (UMF)
An extensible XML dialect used for structuring data source files. UMF contains standard tags that represent key pieces of identities, relationships, and activities. Before data can be processed by the pipelines, it must be converted into UMF and follow the UMF specification.

Universal Naming Convention (UNC)
The server name and network name combined. These names together identify the resource on the domain.

universal port (U_port)
A switch port that can operate as a generic port (G_port), an expansion port (E_port), a fabric port (F_port), or a fabric loop port (FL_port). A port is defined as a U_port when it is not connected or has not yet assumed a specific function in the fabric.

universal product code (UPC)
A standard bar code, commonly used to mark the price of items in stores, that can be read and interpreted by a computer.

Universal Serial Bus (USB)
A serial-interface standard for telephony and multimedia connections to personal computers.

Universal Service Ordering Code
A code that is used to identify the telecommunication service and equipment provided by the service provider.

universal table space
A table space that is both segmented and partitioned. See also partition-by-growth table space, range-partitioned table space, segmented table space.

Universal Unique Identifier
See Universally Unique Identifier.

A highly portable operating system that features multiprogramming in a multiuser environment. The UNIX operating system was originally developed for use on minicomputers, but was adapted for mainframes and microcomputers. The AIX operating system is IBM's implementation of the UNIX operating system.

UNIX authentication
The process of identifying a client process, which requires that the client process send credentials to the server.

UNIX file
An object that exists in a hierarchical file system. Examples of UNIX files are HFS, ZFS, NFS, and TFS.

UNIX file system (UFS)
A section of the UNIX file tree that is physically contained on a single device or disk partition, and that can be separately mounted, unmounted, and administered.

UNIX filter
In UNIX operating systems, a program that obtains data from standard input (STDIN) and returns the results to standard output (STDOUT). See also DLL filter.

UNIX System Services (USS)
An element of z/OS that creates a UNIX environment that conforms to XPG4 UNIX 1995 specifications and that provides two open-system interfaces on the z/OS operating system: an application programming interface (API) and an interactive shell interface.

UNIX-to-UNIX Copy Program (UUCP)

  1. The command (uucp) that starts file copying from one or more sources to a single destination.
  2. A group of commands, programs, and files that allows the user to communicate with another UNIX system over a dedicated line or a telephone line.

unknown device
A group of resources that have not been discovered and are not yet populated in the data model.

unlicensed software
Software that is installed or used without being associated with an active license or that is installed or used outside of the scope defined in the license agreement.


  1. In social networking, to withdraw support from something that has been posted. See also like.
  2. Pertaining to two or more different operating environments. For example, unlike distribution is distribution between DB2 for i5/OS and DB2 environments.

unlike devices
Devices that have different track capacities or a different number of tracks per cylinder.

Unlimited Strength Policy File
See Java Cryptography Extension.

In IDDU, to remove the association between a database file on disk and a file definition in a data dictionary. See also link.

To remove a volume from a tape unit or a direct access device.

Pertaining to a status where the optical image associated with the selected image catalog entry that is not active or not loaded in the active virtual optical device. Only image catalog entries with a status of mounted or loaded can be accessed through the virtual optical device.

unload file
A timestamped snapshot of RACF database contents. Unload files are used for multiple tasks, such as maintaining data backups, database content mergers, and database content comparisons for audits and troubleshooting.


  1. To remove software that was placed on a device to limit the users access to facets of that device.
  2. To allow an authorized user to remove the lock from a locked contract.
  3. To release an object or system resource that was previously locked and return it to general availability.

A function that immediately stops PowerHA SystemMirror cluster services on a cluster node without stopping the applications under the control of PowerHA SystemMirror.

unmanaged device
A device that is known to the cluster but not provisioned, monitored, or updated. Defining a device as unmanaged in the cluster prevents the IP address from being used by the provisioning engine.

unmanaged node

  1. See unmanaged device.
  2. A node that is defined in the cell topology that does not have a node agent that manages the process. An unmanaged node is typically used to manage web servers.

unmanaged web application
A web application with a lifecycle that is managed outside of the administrative domain. By creating a representation of these applications that are deployed through external tools, the on demand router can prioritize and route HTTP requests to the application.

unmapped conversation
See basic conversation.

To copy data from a remote procedure call packet by using a stub. See also marshal.

unmatched member
A dimension member that does not relate to any member in the reference data.

unmatched request
A SIP request that has To and From tags but whose related dialog is not found in the SIP container because the dialog was never created or is in the invalidated state.

unmatched response
A SIP response that is received in the SIP container but is not matched to any outgoing requests.

unmatched row
A row of data that does not contain enough information to meet specified join conditions. As a result, the row is blank.

unmodeled fault
A fault message that is returned from a service that has not been modeled on the Web Services Description Language (WSDL) port type.

To logically disassociate a mountable file system from another file system.

unnamed row data type
A row data type created with the ROW constructor that has no defined name and no inheritance properties. Two unnamed row data types are equivalent if they have the same number of fields and if corresponding fields have the same data type, even if the fields have different names. See also row data type.

In communications, pertaining to a frame format that provides additional control functions, such as XID, DISC, DM, SABM, SABME, UA, and FRMR.

unnumbered acknowledgment (UA)
In communications, a data link command or response that acknowledges the receipt and acceptance of the SABM, SABME, and DISC command protocol data units.

In binary floating-point, describing the relationship that exists between two values when they cannot be arranged according to relative value. The relationship between two values is unordered either when a not-a-number is compared to any value or when infinity is compared to any value other than infinity.

unpacked decimal format
See zoned decimal format.

An event sent by a object in the pend state that results in the moving of the object to the online state. See also pend.

To remove the designation of higher priority to a community or forum topic if it no longer needs to be given that prominence.

unplanned accessorial
A standard accessorial that users can assign to individual shipments. An unplanned accessorial must be assigned to a contract or section.

unplanned remote takeover
In an RSR environment, a remote takeover initiated by the tracking IMS to transfer the workload from the active IMS to the tracking IMS at the remote site without waiting for an orderly shutdown of the active IMS. See also remote takeover.

The property of an architecture rule that does not require reports when violations of the rule occur.

unprintable area
The area of a sheet of paper (or form) on which no printing can be done because of printer hardware limitations.

unprivileged state
A hardware protection state in which the processor can only run unprivileged instructions. The processor's unprivileged state supports the virtual machine's operating system state and problem state. See also privileged state.

unprotected conversation
An LU 6.2 conversation that has a synchronization level of none or confirm. If conversation errors or failures occur, the resources used by the application might be in inconsistent states.

unprotected field
A displayed field in which a user can enter, modify, or delete data.

unprotected logical unit of work
The logical unit of work that is used in an unprotected conversation. See also unit of recovery.

unprotected logical unit of work identifier
The logical unit of work identifier that is used in an unprotected conversation.

unprotected storage
The part of the system auxiliary storage pool (ASP) that is not protected by mirrored protection or device parity protection.

unprotected volume
A volume that is recognized by the AS/400 host as an unprotected device, even though the storage resides on a Redundant Array of Independent Disks (RAID) and is therefore fault tolerant by definition. The data in an unprotected volume can be mirrored. An unprotected volume is also referred to as an unprotected device.

To remove files from depot servers after they have been successfully distributed and installed on target computers.

unqualified call
In IMS, a Data Language/I (DL/I) call that does not contain a segment search argument.

unqualified segment search argument
A segment search argument that contains only a segment name that specifies the segment type to be accessed. See also segment search argument.

unreachable code
A set of instructions that cannot be reached during program execution. Unreachable code is detected and removed as part of optimization.

unread journal log
A log that keeps unread lists synchronized between various replicas of a Notes database and records when a document's status changes from read to unread and vice-versa.

Pertains to a web diagram node that is not yet associated with an actual resource. See also realize.

To adjust inventory receipt quantity to correct errors incurred during receiving.

unrecognized screen
In the 3270 terminal service development tools, a screen that cannot be identified by any of the recognition profiles currently defined.

unrecoverable error

  1. A printer error condition that cannot be automatically corrected and requires an external operation for possible correction. This error causes, for example, the end of a job, program, hardware function, page, or printing.
  2. An error for which recovery is impossible without use of recovery techniques external to the computer program or run.

unrecoverable transaction
See nonrecoverable transaction.

unrefined model
A model that contains information extracted from the data but which is not designed for generating predictions directly. See also Apriori.

To separate resolved identities into two separate entities.

unresolved import
An import whose type and name do not yet match the type and name of an export.

unrolling loop
See loop unrolling.

unserviceable request
A request to run an activation of an activity which currently cannot be satisfied, either because the activity is not available or because the region on which the request must run is inaccessible.

unshielded twisted pair (UTP)
A cable medium with one or more pairs of twisted insulated copper conductors bound in a single sheath.

The process of attaching a transaction to provide an environment under which to resume the processing of a shunted unit of work.

unsigned binary number (UBIN)
In architecture, a data type for architecture syntax, indicating one or more bytes to be interpreted as an unsigned binary number.

unsigned security token
An authentication specification used to verify the recipient of the message containing the token. Unsigned tokens often consist of login credentials supplied by the service requestor, for example, a user name token.

Pertaining to the act of providing information or actions to a resource, without the resource having requested the information or action. See also solicited.

unsolicited data
A type of inbound data that arrives on a connection where no FEPI conversation is active.

unsolicited-data handler
A user-provided part of a FEPI application that handles unsolicited inbound data.

unsolicited email
Unwelcome and bothersome email. See also ham.

unsolicited message
A message that is not a response to a command. See also program operator, solicited message.

unsolicited output message
An output message that is not generated as a response to an input command. For example, a system informational message is an unsolicited output message.

unsolicited statistics
CICS statistics automatically gathered by CICS for a dynamically allocated and deallocated resource (for example, an autoinstalled terminal) when the resource is about to be deleted. See also end-of-day statistics, interval statistics, requested reset statistics, requested statistics.

See United Nations Standard Products and Services Classification.

unstructured data
Any data that is stored in an unstructured format rather than in fixed fields. Data in a word processing document is an example of unstructured data. See also structured data.

unstructured information
Data that is not contained in a fixed location, such as the natural language text document.

Unstructured Information Management Application
A software system that analyzes large volumes of unstructured information in the form of text, audio, video, or other media to discover, organize, and deliver relevant knowledge to the application user.

Unstructured Information Management Architecture (UIMA)
An Apache architecture that defines a framework for implementing systems, such as Watson systems, for the analysis of unstructured data.

Unstructured Information Management Architecture framework (UIMA framework)
A Java-based implementation of the UIMA architecture. It provides a run-time environment in which developers can plug in and run their UIMA component implementations and with which they can build and deploy UIM applications.

Unstructured Supplementary Service Data (USSD)
A communication technology that is used by GSM cellular telephones to send text messages between a mobile phone and an application program in the network. USSD establishes a real-time session between the mobile phone and the application that handles the service.

In architecture, unmarked portion of a physical medium. See also toned.

untrusted system
A system in a network over which you do not have control of security.

untyped collection variable
A generic ESQL/C collection variable or SPL variable that can hold a collection of any collection data type and takes on the data type of the last collection assigned to it. See also typed collection variable.

untyped expression
A parameter marker or null value that is specified without a target data type. See also untyped parameter marker.

untyped parameter marker
A parameter marker that is specified without its target data type. See also parameter marker, typed parameter marker, untyped expression.

In cross-site mirroring, pertaining to the mirror copy data state that indicates that the mirror copy contains incoherent data. This occurs (a) during synchronization because synchronization does not preserve the order of writes and (b) if a failure occurs while performing geographic mirroring in asynchronous mode.

Pertaining to a metadata object that is not affected by version control, and can be changed at any time, regardless of the lock status of the current version.

unweighted count
In a weighted table, the actual number of recorded responses. In an unweighted table, the counts and unweighted counts are identical.

See unit of measure.

See unit of work.

See uniprocessor.

See user printable area.

See universal product code.

An object of a class that is cast to a more general class in the inheritance hierarchy. See also casting, downcasting.

The ability of a cursor to perform positioned updates and deletes. The updatability of a cursor can be influenced by the SELECT statement and the cursor sensitivity option that is specified on the DECLARE CURSOR statement.

updatable result set
A result set that is associated with a cursor that was created with a SELECT statement that contains the FOR UPDATE clause.


  1. Software maintenance such as a manufacturing refresh, refresh pack, or fix pack that changes the modification level of a product.
  2. To modify a file or data set with current information.
  3. To apply fixes to a system.

update access
An access intent that establishes the intent of an application to modify the database. Other applications may read the database if they do not need to be protected from the updater's incomplete changes.

update-anywhere replication
In SQL replication, a type of replication in which all tables are both registered sources and read/write targets. One table is the primary source table for performing a full refresh of all of the others. See also master table, multitier replication, peer-to-peer replication, replica table.

update authority
A data authority that allows the user to change the data in an object, such as a journal, a message queue, or a data area.

update detection
See time-based update detection.

update file
In RPG, a file from which a program reads a record, changes data fields in the record, and writes the record back to the location from which it came.

update hole
The location on which a cursor is positioned when a row in the result table is fetched again but values in the underlying tables have been updated such that the row no longer satisfies the search condition. See also delete hole, hole.

update intent
In IMS, DL/I, or SQL/DS, the type of access intent that allows a subsystem to insert, delete, or replace records on a database. See also scheduling intent.

update lock

  1. A lock that limits concurrently executing application processes to read-only operations on the data if these processes have not declared that they might update the row.
  2. In Informix, a promotable lock that is acquired during a SELECT...FOR UPDATE. An update lock behaves like a shared lock until the update actually occurs, and it then becomes an exclusive lock. See also promotable lock.

update-only recovery
A facility that allows the user to define inquiry transactions as unrecoverable.

update operation
An I/O process that changes the data in a record.

update rule
A condition enforced by the database manager that must be met before a column can be updated.

update script
A shell script or executable file created by the developer of an application program to update the program. The script file must follow specific guidelines to be compatible with the program update tools that are provided in the operating system.

update time stamp (UTS)
In the DCE Cell Directory Service (CDS), an attribute that identifies the time at which the most recent change was made to any attribute of a particular CDS name. For directories, the UTS reflects changes made only to attributes that apply to the actual directory (not one of the replicas).

update transaction
A transaction in the data chaining (DC) feature system with capabilities to update a database. Update transactions are recoverable.

update trigger
A trigger that is activated by an update operation on the table or view that is specified in the trigger definition. See also delete trigger, insert trigger, instead of trigger, read trigger, trigger.

up fold
A fold that points up from the horizontal surface when fanfold forms are unfolded and held horizontally. Fanfold forms are alternately folded with up and down folds. See also down fold.


  1. To install a new version or release of a product to replace an earlier version or release of the same product.
  2. Any hardware or software change to a later release, or any hardware addition or software addition.
  3. See update.

upgradeable lock
A lock that identifies the intent to update a cache entry when using a pessimistic lock.

upgrade count
A total number which identifies licenses in the upgrade set.

upgrade index
A unique number which identifies a specific license in the upgrade set. The upgrade index is always less then or equal to the upgrade count.

The collapsing of data from a lower level so that it can be represented at a parent level.

Pertaining to controllers that are above devices, and lines that are above controllers in a communications configuration. See also downline.

To transmit data from a computer to a central computer or network, or to an attached device such as a printer.

upper bound
A limit that indicates the greatest value that a variable can assume. In operations research, an upper bound may or may not be in the domain of a variable. When an upper bound is in the domain of the variable, the variable may assume precisely that value, but no greater. When an upper bound is not in the domain of the variable, the variable may assume values strictly less than the upper bound, but not precisely the upper bound itself. See also bound, bound strengthening, least upper bound, lower bound.


  1. Pertaining to the capital alphabetic characters, as distinguished from the small alphabetic characters. The concept of case also applies to alphabets such as Cyrillic and Greek, but not to Arabic, Hebrew, Thai, Japanese, Chinese, Korean, and many other scripts. Examples of capital letters are A, B, and C. See also lowercase.
  2. Pertaining to those graphic characters of a layer which can be input from a keyboard by using the normal shift key (IBM Corp. Std. C-S 2-0161-008).

upper-layer timeout value (ULP_TOV)
The minimum time that a Small Computer System Interface (SCSI) upper-layer protocol (ULP) process waits for SCSI status before initiating ULP recovery.

upright posture
Property of a vertical typeface such as Roman. See also inclined posture.

See uninterruptible power supply.

The recommendation of a related yet pricier product in the same product line as the currently displayed or selected product. See also accessory, cross-sell.


  1. Pertaining to the direction from driver to stream head.
  2. Pertaining to the direction of the flow, which is from the start of the process (upstream) toward the end of the process (downstream).
  3. Pertaining to the direction opposite to data flow, which is toward the source of a transmission. See also downstream.

upstream data
In architecture, IPDS commands that exist in a logical path from a specific point in a printer back to, but not including, host presentation services.

See mean time between failures.

upward-growing stack
With Extra Performance Linkage (XPLINK), a stack that grows from low addresses to high addresses in memory.

upward integration
The methods, processes and procedures that enable lower-level systems-management software, such as IBM Director Agent, to work with higher-level systems-management software, such as Tivoli Enterprise or Microsoft SMS.

upward integration module
Software that enables higher-level systems-management software, such as Tivoli Enterprise or Microsoft Systems Manager Server (SMS), to interpret and display data provided by IBM Director Agent. This module also can provide enhancements that start IBM Director Agent from within the higher-level systems-management console, as well as collect IBM Director inventory data and view IBM Director alerts.


  1. See uncommitted read.
  2. See unit of recovery.

urban heat island
A metropolitan area that is significantly warmer than the rural areas around it, due to the use of concrete in buildings and road surfaces, waste heat from vehicles, and air pollution.

See unit reference code.

See Uniform Resource Identifier.

See unit of recovery identifier.

See Uniform Resource Locator.

URL scheme
A format that contains another object reference.


  1. See user-replaceable module.
  2. See Unified Resource Manager.

See Uniform Resource Name.

In cross-site mirroring, pertaining to the mirror copy data state that indicates that the correct order of updates to the mirror copy from the production copy is being preserved, but the mirror copy may be outdated. The usable mirror copy data state occurs (a) when the system performs geographic mirroring in synchronous mode, (b) after successfully suspending geographic mirroring, and (c) when the mirror copy is successfully detached.

usable area
An area on a physical medium that can be used to present data.

usage license charge (ULC)

usage list
A database object that records each DML statement section that references a particular table or index and captures statistics about how that section affects each object as the section executes.

usage time
The total time that a user, other than the asset owner, takes to gain value from an asset, measured in hours, days, months, or years.

usage type
In i5/OS, a license management function that monitors usage by tracking the number of license users. Concurrent usage type indicates the usage limit is for the number of unique jobs using the product at the same time. Registered usage type indicates the usage limit is for the number of unique license users registered to use the product.

usage URI
The fully qualified name of a subclass of data within the resource type that is retrieved from the OSLC provider application.

See user spool access method.

See Universal Serial Bus.

USB key
See flash drive.

use attribute
The attribute assigned to a direct access storage device (DASD) volume or system-managed tape volume that controls when the volume can be used to allocate new data sets. The use attributes for DASD volumes are public, private, and storage. The use attributes for system-managed tape volumes are scratch and private. See also scratch.

use authority
An object authority that allows the user to run a program or to display the contents of a file. Use authority combines object operational authority, read authority, and execute authority.

use case

  1. The specification of a sequence of actions that a system can perform, interacting with users of the system. Use cases are used in system analysis to identify system requirements. See also scenario.
  2. A technique for identifying user requirement by providing scenarios that illustrate how users and systems interact. In WebSphere Commerce, a use case shows the flow of each user interaction in the starter store and acts as a template for creating a store.

use code
A standard rule that matches an element or field against a predefined code table, specifies whether or not a compliance error is generated if the element or field does not contain one of the values in the code table, and stores a code’s description in another element or field.

use count
Number of tasks using a program concurrently. This is maintained by CICS in the program processing table.

used track
A track from the beginning of data sets to the last-used track.

use-once license
A type of license, administered by the license server, that is effective for only a single instance of starting a product or using a service. The license server decrements the number of available use-once licenses each time the product or service is used.

Any individual, organization, process, device, program, protocol, or system that uses the services of a computing system.

user abend
A request made by user code to the operating system to abnormally terminate a routine. See also system abend.

user account

  1. The login directory and other information that gives a user access to the system.
  2. An administrative page in the service that specifies a user's name, login information, subscriptions, and roles.

user address space
An address space that has at least one MVS task known to the kernel address space. This address space can contain a shell or an application program that uses UNIX System Services.

user administrator
A person who adds new users and ensures security by giving users membership of role-based authorization groups with appropriate permissions.

user agent

  1. An application that browses the web and leaves information about itself at the sites that it visits. In enterprise search, the web crawler is a user agent.
  2. In OSI X.400, one of two basic parts of electronic mail. A user agent is a program that provides access to the mail system. This program allows users to compose, send, and receive mail.
  3. A broad class of entities that can access servers across a network. This broad class includes desktop browsers, bots, and mobile devices, among others.
  4. A client that initiates a request for a local service to establish a connection to a remote server.

user area
The parts of main storage and disk available to the user.

user ASP

  1. One or more storage units used to isolate some objects from the other objects that are stored in the system ASP and other user ASPs. User ASPs are defined by the user.
  2. One or more auxiliary storage pools used to isolate journals, journal receivers, and save files from the other system objects stored in the system ASP. See also auxiliary storage pool, system ASP.

user assistance
The product interfaces and technical product information that help users complete their tasks. User assistance includes wizards, interface instructions, and contextual assistance topics, as well as information centers and books.

user attribute
The privileges, restrictions, and processing environments assigned to a user. See also group-related user attribute.

user attribute data set (UADS)
In Time Sharing Option (TSO), a partitioned data set with a member for each authorized user. Each member contains the appropriate passwords, user identifications, account numbers, logon procedure names, and user characteristics that define the user.

user authentication
In RACF, part of security checking at sign-on. It consists of identification of the user ID and verification of the password or of the user identification card.

user bag
In the MQAI, a type of data bag that is created by the user.

user-based pricing
A pricing option that provides the capability for the customer to pay for the licensed program on the basis of the number of users.

user block (ublock)
In kernel mode, the data structure that contains system information about a user process, such as its real and effective user IDs, the list of open file descriptors, and signal-handling settings.

user buffering
The use of a work area in the processing program's address space for an I/O buffer; the Virtual Storage Access Method (VSAM) transmits the contents of a control interval between the work area and direct access storage without intermediary buffering.

user buffer pool (UBUF)
An area in each user's address space that has been divided into buffers.

user catalog
An optional catalog used in the same way as the master catalog and pointed to by the master catalog. Employing a user catalog lessens the contention for the master catalog and facilitates volume portability.

user catalog connector
See catalog connector.

User Centered Design (UCD)
A development approach that helps ensure that application designs will meet the user's needs and provide usable applications. See also information architect.

user certificate
A certificate associated with a user ID that is used to authenticate the user's identity, and can also represent a server. See also digital certificate.

user class

  1. A z/VM privilege category assigned to a user of a guest virtual machine in the user's directory entry; each class specified allows access to a logical subset of all the z/VM Control Program (CP) commands.
  2. See custom view.
  3. The classification of a user by the system task, such as security officer, security administrator, programmer, system operator, and user. Each user class has a set of special authorities depending on the security level of the system. The user class determines which options are shown on the IBM-supplied menus.

user configuration
In System i Access, the set of files, created by the System i Access administrator, that define the user's System i Access configuration and the functions used. The files include the configuration file and the command file.

user-controlled environment
An extended program model (EPM) environment that is explicitly created using the QPXXCALL program.

user copy table
In SQL replication, a replication target table whose content matches all or part of a registered source table and contains only user data columns.

user correlator
A 4-byte value supplied to VTAM by an application program when certain macroinstructions (such as REQSESS) are issued. It is returned to the application program when subsequent events occur (such as entry to a SCIP exit routine upon receipt of BIND) that result from the procedure started by the original macroinstruction.

user-created data stream
A data stream that has not been validated by a system program on the system when the data was spooled.

user credential
Information acquired during authentication that describes a user, group associations, or other security-related identity attributes, and that is used to perform services such as authorization, auditing, or delegation. For example, a user ID and password are credentials that allow access to network and system resources.

user database
A database that records and stores information about change requests.

User Datagram Protocol (UDP)
An Internet protocol that provides unreliable, connectionless datagram service. It enables an application program on one machine or process to send a datagram to an application program on another machine or process.

user data segment
In kernel mode, the virtual memory segment that contains user data, which consists of initialized data variables.

user data set
In z/OS, a data set defined to RACF in which either the high-level qualifier of the data set name or the qualifier supplied by an installation exit routine is a RACF user ID. See also group data set.

user-defined aggregate (UDA)
An aggregate function that is not provided by the database server (is not built in) that includes extensions to built-in aggregates and newly defined aggregates. The database server manages all aggregates.

user-defined cast (UDC)
A cast that a user creates with the CREATE CAST statement. A user-defined cast typically requires a cast function. A user-defined cast can be an explicit cast or an implicit cast. See also cast.

user-defined character (UDC)

  1. A character which is defined by an individual user or organization for assignment in one or more code pages. These characters are often ideographic characters, symbols or logos. Some standards, including Unicode, reserve coding space for user defined characters. The meaning of the user defined character can only be assured within the closed environment of the defining organization or by private agreement among cooperating users.
  2. A character that is created through the Character Generator Utility (CGU). CGU is an extension of the code page with special user-defined ideographic characters, symbols, or logos. User-defined characters may be present in some of the Japanese, Chinese, and Korean code pages.

user-defined collating sequence
In Query, a collating sequence defined by the user that replaces the EBCDIC collating sequence provided by the system for sorting fields in a query report.

user-defined column
In metric management, a column used to represent a value other than the actual or target. It may be an industry benchmark or any other useful additional numerical information for a period, including a calculation based on the other values of the metric. User-defined columns may be different for each metric type.

user-defined communications support
An i5/OS function that provides an application program interface (API). User-defined communications support allows user-written application programs to call routines to set up and use a communications protocol over a token-ring, Ethernet, or X.25 network.

user-defined data stream (UDDS)
A data stream in which the user has defined and embedded all device control characters.

user-defined data type

  1. A data type that is defined for use in a relational database. One can define opaque data types and distinct data types. See also data type.
  2. A data type that is defined to the DB2 database system by using the CREATE TYPE statement, and can be referenced thereafter in SQL statements. See also distinct type.

user-defined edit code
A number (5 through 9) indicating that editing should be done on a numeric output field according to a pattern predefined to the system program. User-defined edit codes can take the place of edit words, so that repetitive coding of the same edit word is not necessary.

user-defined event
An event defined by the BTS application programmer. The BTS user-defined events are activity completion events, input events, and timer events. See also composite event, system event, timer event.

user-defined field (UDF)
A field that is provided to customize the application to a certain extent.

user-defined function (UDF)

  1. A function that is defined to the DB2 database system by using the CREATE FUNCTION statement and that can be referenced thereafter in SQL statements. See also built-in function, external function, function, routine, sourced function, SQL function, table function.
  2. A user-defined routine that returns at least one value. A user-defined function can be written in SPL (SPL function) or in an external language that the database server supports (external function).
  3. A function defined by the user that provides a mechanism for extending C-SQL for use in formulas, including queries, field expressions, and rules.
  4. An internal or external function created by the user. Internal functions are defined within a catalog. External functions are defined in an external, compiled module.
  5. A custom function that can be used to organize code in a policy. See also function.

user-defined global variable
A global variable that is defined to the DB2 database system by using the CREATE VARIABLE statement and that can be referenced thereafter in SQL statements. See also built-in global variable, database global variable, global variable.

user-defined log (UDL)
An object that is associated with a hierarchy or catalog that stores custom content. See also UDL entry.

user-defined procedure

  1. A user-defined routine that does not return a value. You can write a user-defined procedure in SPL (SPL procedure) or in an external language that the database server supports (external procedure). See also procedure.
  2. A procedure that is defined to the DB2 database system by using the CREATE PROCEDURE statement and that can be referenced thereafter in SQL statements. See also built-in procedure, external procedure, procedure, routine, SQL procedure.

user-defined program
A program that a user supplies and defines.

user-defined routine (UDR)
A routine that users write and register in the system catalog tables of a database, and that an SQL statement or another routine can invoke. A user-defined routine is written in SPL or in an external language (external routine) that the database server supports.

user-defined shared library
A set of custom or add-in library routines that provide specific programming operations.

user-defined statistics (UDS)
Information about the opaque data type values in a database that is collected by the UPDATE STATISTICS statement, which calls user-defined functions to calculate the statistics. The optimizer uses these statistics to determine the fastest way to execute an SQL query.

user-defined test
A test that is created by a user in addition to the tests that are automatically created and run.

user-defined type (UDT)
A mechanism that can be used to create new data types. A UDT can extend the capabilities of the built-in data types and capture the unique semantics of user data.

user-defined variable
A shell variable to which the user assigns a character string as a value.

user-defined word
In COBOL, a word, required by a clause or a statement, that must be supplied by the user in a clause or statement.

user definition field
An optional custom field that a customer can define for an order.

user deprovisioning
The process of removing a user account from IBM Security Access Manager for Enterprise Single Sign-On.

user descriptor
A descriptor that is generated by a system or a process, for example, installation-created and node. See also ETO descriptor.

user domain
A CICS domain responsible for identifying users and recording their non-security attributes.

user domain object
An object on the system that can be accessed directly by a user state program. The object types that can be either system domain or user domain are: *USRSPC, *USRIDX, *USRQ, *PGM, *SQLPKG. All other object types are system domain. See also domain.

user dynamic storage area (UDSA)
A storage area in CICS that is allocated below the 16 MB line and reserved exclusively for those user application programs that execute in user-key and that reside below the 16 MB line.

user entry procedure (UEP)
The entry procedure, written by the application programmer, that is the target of a dynamic program call. This procedure gets control from the program entry procedure (PEP). See also program entry procedure.

user event
A macro function that is executed either before or after a query or series of queries are refreshed.

user exit

  1. A point in a program at which a user exit routine may be given control.
  2. A customized routine that takes control at a specific point in an application. See also installation exit.
  3. An extended rule that enables a map to temporarily exit translation and perform functions that are not normally performed during translation.
  4. An application programming interface (API) that provides a call to an external program during the process flow of a message.

user exit class
A Java class that adds custom logic to the processing of integration messages and executes before or after the external exit class executes for publish channels, enterprise services, and invocation channels. See also external exit class.

user exit handler
A CICS program that is invoked at an exit point (other than an exit point in a domain) to handle the user exit program associated with that exit point.

user exit program
A program, written by a user, that receives control at predefined user exit points. When a user exit program is invoked, the database manager passes control to the executable file. Only one user exit program can be invoked in a database manager instance.

user exit programming interface (XPI)
A CICS interface that provides global user exit programs with access to some CICS services. XPI consists of a set of function calls that you can use in your user exit programs to extend or modify CICS system functions.

user exit queue
A structure built by VTAM that is used to serialize the execution of application program exit routines. Only one user exit routine on each user exit queue can run at a time.

user exit routine
A user-written routine that receives control at predefined user exit points.

user experience leader (UX leader)
An individual who uses knowledge of human-computer interaction and user interface design to interpret customers' requirements to create a product that is easy to learn and use, and ultimately to satisfy customer needs. See also interaction designer.

user file
A text file that specifies the users who are allowed or forbidden to use licensed software products.

user function
A macro program that is callable by the user.

user group

  1. See customer group.
  2. A group consisting of one or more defined individual users, identified by a single group name.

user group representative
A person within a user group who is responsible for representing the user group's interests in negotiations with the storage administration group.

user heap
See initial heap.

user ID

  1. See user identification.
  2. See user identifier.

user ID/address
The two-part network name used in the system distribution directory and in the office applications to uniquely identify a user and send electronic mail.

user ID association
A relationship between two user IDs which is required for command direction and password synchronization between the user IDs.

user identification

  1. In the UNIX operating system, a string that uniquely identifies each user to the operating system.
  2. The name used to associate the user profile with a user when a user signs on to a system.
  3. The first part of a two-part network name used in the system distribution directory and in the office applications to uniquely identify a user. The network name is usually the same as the user profile name, but does not need to be. See also common user identification.
  4. A file assigned to every user and server that uniquely identifies them to Notes and Domino.

user identification and verification
The acts of identifying and verifying a RACF-defined user to the system during logon or batch job processing. RACF identifies the user by the user ID and verifies the user by the password or operator identification card supplied during logon processing or the password supplied on a batch JOB statement.

user identification number (uid)
A 4-byte, unsigned integer (uid) used to identify a user profile. See also group identification number.

user identifier (UID, user ID)
A string of characters that uniquely identifies a user to a system. See also effective user identifier, real user ID.

user index

  1. In i5/OS application programming interfaces, an object that provides a specific order for byte data according to the value of the data. User index objects reside in the user domain. The system-recognized identifier for the object type is *USRIDX.
  2. An index that a user creates explicitly with the CREATE INDEX statement. See also attached index, system index.

user information source (UIS)
The user information contents of an unload file, CKFREEZE data set, or live database that are used as input to Tivoli Security Information and Event Manager.

user interface (UI)
The hardware, or software, or both that enables a user to interact with a system, program, or device.

user interface block (UIB)
A control block used in the CALL DLI interface to pass information to the user program. It contains the address of the PCB address list (UIBPCBAL) from the schedule request, and the response code to each DL/I request. A definition of the UIB should only be included in the application program if the UIB is to be referenced. The UIB is acquired by the interface routine when an application program issues a schedule request specifying a pointer reference to be set with the address of the UIB.

user interface client
Any machine in the Gentran Server for Windows system other than the primary system controller or secondary controller(s). The user interface clients provide the functions that are necessary to monitor and control the system.

user interface manager (UIM)
A function of the operating system that provides a consistent user interface by providing comprehensive support for defining and running panels (displays), dialogs, and online help information.

user interface profile
A profile that defines the default behavior, set of features, and the functionality that is available to a user in the Report Studio and Cognos Workspace Advanced user interfaces.

user interface sketch
A mock-up of a graphical user interface at any one point in the application's operation.

user item
In the MQAI, a type of data item that is created by the user.

user key
A storage key that can be used by processes when running in user mode (as opposed to kernel node).

user-key storage
Storage obtained by CICS in MVS open-key storage. It is for user application programs and their associated data areas. It can be accessed and modified by user applications and by CICS. See also CICS-key.

user library
A private print-resource library owned by an individual user, accessed only when the name is specified by the owner in the JCL USERLIB parameter. See also system library.

user-maintained data table (UMT)
A type of CICS data table that has no CICS-supported association with its source data set after it has been loaded. Changes to the table are not automatically reflected in the source data set.

user mapping

  1. A process that associates users to operating system properties to enable access to Informix and to control the level of privileges.
  2. The association of Information Integrator for Content user IDs and passwords to corresponding user IDs and passwords in one or more content servers. User mapping enables single logon to Enterprise Information Portal and multiple content servers.
  3. In a federated system, the association between the authorization ID at the federated server and the authorization ID at the data source. See also user option.

user message queue
A user-created object used to receive messages sent from the system, other users, and application programs.

user message table
A table of messages generated by the user and used by certain user written edit routines.

user mode
A mode in which a process is carried out in the user's program rather than in the kernel. See also kernel mode.

user name
A string of characters that uniquely identifies a user to a system.

user name token
A type of token that is represented by a user name and optionally, by a password.

user number (UID)
In UNIX systems, a number that uniquely identifies a user to the system. The UID is the internal number associated with a user ID.

user option
In a federated system, a parameter of the CREATE USER MAPPING or ALTER USER MAPPING statement to which values related to authorization are assigned. See also user mapping.

user password
A unique string of characters that a system user enters to identify that user to the system, if the system resources are secured.

user permission
The authority granted to a user to give them access to view and work with portal resources. This authority is granted by membership of a user role group.

user pool
An optional storage pool that contains blocks of data that compose the files that are created by SAN File System clients. See also default user pool, storage pool.

user port
In IP PrintWay, a port address that is outside the range of predefined addresses.

user portal
A portal that ties together all modules within Emptoris Sourcing. The user portal contains portlets each of which displays data from the specific area that it represents. The contents and display of the portal can be customized.

user printable area (UPA)
The area within the valid printable area (VPA) where user-generated data can print without causing an exception condition. See also physical printable area, valid printable area.

user privilege
A particular function permission that can be assigned to specific user types. See also field permission.

user profile

  1. A description of a user that includes such information as user ID, user name, password, access authority, and other attributes that are obtained when the user logs on. See also profile.
  2. A file in the user's home directory named .profile that contains shell commands that set initial user-defined characteristics and defaults for the login session.
  3. An entity such as a department or customer for whom services are being performed.
  4. An object with a unique name that contains the user's password, the list of special authorities assigned to a user, and the objects the user owns. The system-recognized identifier for the object type is *USRPRF.

user profile name
The name or code that the system associates with a user when the user signs on the system.

user provisioning
The process of signing up a user to use IBM Security Access Manager for Enterprise Single Sign-On.

user proxy definition
A definition that maps remote and local user IDs, and enables users at remote nodes to submit work to the local node without explicitly defining user IDs and passwords in the processes, which eliminates having to share passwords with trading partners. See also secure point of entry.

user queue

  1. In i5/OS application programming interfaces, an object consisting of a list of messages that communicate information to other application programs. The system-recognized identifier for the object type is *USRQ.
  2. A queue that holds work items waiting to be completed by a user rather than by an automated process. Each user's queue displays as an inbox. See also queue.

user registration properties file
A file on the WebSphere Commerce Server that contains information needed to support the correct language and country or region for a store.

user registry

  1. A collection of user information, such as user IDs and passwords, that is used as the basis for security control by a system such as a web application server.
  2. A database of known users and user-provided information that is used for authentication purposes.

user-related activity
An activity that requires human involvement. Such an activity cannot be started automatically by BTS, because it is dependent on a user being ready to process the work.

user-replaceable module (URM)
See user-replaceable program.

user-replaceable program
A CICS program that is invoked at a particular point in CICS processing as if it were part of CICS code. You can modify the supplied program by including your own logic, or replace it with a version that you write yourself. Examples include the dynamic routing program, and the transaction restart program.

user role

  1. An identifier that is assigned to a user that defines the set of tasks that the user can perform.
  2. A role assigned to a user in a user account that determines whether a user can use the service and whether the user has the ability to perform administrative tasks.

user role group
A group that assigns membership to give a new user the appropriate level of access to the solution. Each new user is added as a member of the appropriate role group. There are different permission levels associated with each role group.

user security
That part of a security facility that verifies that a user is authorized to (a) sign on to a local or remote system (b) run a transaction and (c) to access the resources and use the commands that a transaction invokes. See also session security.

user selector
In the WebSphere MQ Administration Interface (MQAI), the identifier that is placed with a data item into a data bag to identify the data item. WebSphere MQ provides predefined user selectors for WebSphere MQ objects.

user sentiment
A user-rating score that is derived from gathering users' application ratings from the major online retail application stores (for example, iTunes). The function crawls all ratings and reviews to generate a cumulative mobile app score that combines app quality, user satisfaction, and the overall amount of positive and negative feedback that users provide.

user sequence
A database object that is independent of any one table that automatically generates unique key values based on initial user specifications.

user session
Any APPC session other than a SNASVCMG session.

user shell
An interactive shell. The user's CICS application program runs directly under this CICS facility.

user space

  1. In i5/OS application programming interfaces, an object consisting of a collection of bytes that can be used for storing any user-defined information. The system-recognized identifier for the object type is *USRSPC.
  2. The address space seen by a process in user mode.

user spool access method (USAM)
Data management routines that do not execute in the address space, but provide the subsystem interface for various functions of user data sets.

user stack
An independent area of stack storage that may be located above or below 16 MB, designed to be used by both library routines and compiled code.

user state program
A program that can access objects in the user domain. All user programs on the system are user domain. A user state program can call only another user state program.

user storage pool
A storage pool containing the blocks of data that make up user files.

user story
In agile software development, a requirement that is defined by the customer's needs and presented in the context of a scenario.

user structure

  1. In kernel mode, the data area that contains information that must be accessible while a process runs. The user structure (defined in the /usr/include/sys/user.h header file) specifies the exact information that is kept in the user block; one user structure is allocated for each active process.
  2. A set of control blocks, including a user block and one or more LTERM blocks. The message queues are associated with the dynamic user, as opposed to the physical terminal, and they are queued to the user ID.

user table

  1. An installation-defined table that is used to extend, modify, or delete the default processing specifications. See also table pair.
  2. In SQL replication, a table created for and used by an application before it is defined as a replication source. A user table is used as the source for updates to read-only target tables, consistent-change-data tables, replicas, and row-replica tables.
  3. A list of user IDs authorized to a System i finance job.

user team
A collection of users who have common data access requirements.

user temporary table space
A temporary table space that is used to store declared temporary tables. A user temporary table space is not created by default when a database is created. See also temporary table space.

user thread
The primary thread that the database server runs to service client applications. A user thread also includes a thread to service requests from the onmode utility, threads for recovery, and page-cleaner threads. See also thread.

user time

  1. In UNIX, the time spent executing database manager code.
  2. The amount of time a program is running in the CPU. Does not include time associated with operating system services provided to the program, the program's I/O time, or time in which other processes preempt the program's use of the CPU. See also system time.

user token (UTOKEN)
The RACF security token that encapsulates or represents the security characteristics of a user. RACF assigns a UTOKEN to each user in the system. See also resource token, security token.

user-to-network interface (UNI)
The interface between the ATM endsystem (the user) and the ATM network.

user transaction
A user-written transaction.

user translation object
A translation object that controls data entry, importing, exporting, document turnaround, and creating printed reports.

user-triggered transaction
A transaction that is executed based on user actions.

user type
A description of a particular user’s abilities and the role they assume in a folder. User types include Standard User, Administrator and No Access. See also folder role.

user value unit (UVU)
A unit of measure by which a program can be licensed that is based on the number and type of users for the program.

user view
In logical data modeling, a model or representation of critical information that a business requires.

user volume
A volume, assigned to a user, that can contain any data and can be rewritten as many times as the user wishes until the volume expires.

user-written condition handler
A routine that analyzes and possibly takes action on conditions presented to it by the condition manager.


  1. See unformatted system service.
  2. See Uniform Symbol Specification.
  3. See UNIX System Services.

See Unstructured Supplementary Service Data.

See Coordinated Universal Time.

Unicode Transformation Format, 16-bit encoding form, which is designed to provide code values for over a million characters and is a superset of UCS-2. The CCSID value for data in UTF-16 format is 1200. See also UCS-2, UTF-8.

Unicode Transformation Format, 8-bit encoding form, which is designed for ease of use with existing ASCII-based systems. The CCSID value for data in UTF-8 format is 1208. See also UCS-2, UTF-16.


  1. The provider of a resource such as water, gas, or electricity.
  2. In WebSphere MQ, a supplied set of programs that provide the system operator or system administrator with facilities in addition to those provided by the WebSphere MQ commands.
  3. The capability of a system, program, or device to perform the functions for which it is designed.
  4. A provided resource, such as water, gas, or electricity.
  5. A mechanism used to run different tasks to meet a specific business purpose. For example, importing data from a different database.
  6. A computer program in general support of computer processes. Examples of a utility are a diagnostic program, a trace program, and a sort program.

utility computing
A usage model in which customers pay for computational resources through an established fee-per-time schedule.

utility control facility (UCF)
An optional facility that provides a method of performing most database utility and maintenance operations in preparation for recovery and reorganization.

utility device
The ESA/390 term for the device used with Extended Remote Copy (XRC) to access information that describes the modifications performed on the source copy.

utility program
A computer program in general support of computer processes; for example, a diagnostic program, a trace program, a sort program.

utility routine
A routine in general support of the processes of a computer, for example, an input routine.

utility server
A Content Manager component that is used by the database utilities for scheduling purposes. You configure a utility server when you configure a resource manager or library server. There is one utility server for each resource manager and each library server.

utility volume
A volume that is available to be used by the extended remote copy (XRC) function for maintenance purposes. The utility volume accumulates change data from the source that is used by the data mover software to update the target volume.

See user token.

See unshielded twisted pair.

See update time stamp.

A spoken word, phrase, or sentence that can be preceded and followed by silence.

See UNIX-to-UNIX Copy Program.

See Universally Unique Identifier.

See user value unit.

UX leader
See user experience leader.