A B C D E F G H I J K L M N O P Q R S T U V W X Y and Z Special characters and Numerics

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


See high availability.

An unauthorized person who tries to gain access to protected resources on a system. See also attacker, cracker.

See High Availability Control Workstation.

See high availability disaster recovery.

HADR log spooling
The ability for the log replay process on the HADR standby database to read transaction logs from disk and the log receive buffer, instead of from only the log receive buffer. This ability prevents transactions on the primary database from being blocked when replay on the standby database is relatively slow during a primary database load spike.

HA group
A collection of one or more members used to provide high availability for a process.

See hardware abstraction layer.

See high availability large database.

HALDB master
A named entity of a high availability large database that represents only the structural definition of data and refers to the entire collection of partitions.

See HALDB online reorganization.

HALDB online reorganization (HALDB OLR)
A function of IMS that allows non-disruptive, online reorganization of PHDAM and PHIDAM partitions.

HALDB partition
A named entity of a high availability large database that represents a partition of an HALDB.

To round off a number by adjusting the last significant digit. When the number to the right of the last significant digit is 5 or greater, add 1 to the digit. For example, 2.475 half-adjusted to two decimal places becomes 2.48, but 2.474 becomes 2.47.

half-duplex (HD, HDX)
Describing a communications connection over which only one device at a time can transmit data. See also duplex.

half-duplex operation
A mode of operation that allows messages to be transmitted in both directions, but not simultaneously.

half-duplex transmission
Data transmission that can be transmitted in either direction, one direction at a time.


  1. In SNA, one of the locations in a logical connection in a network.
  2. A session-layer component consisting of the combination of data flow control and transmission control components comprising one end of a session. See also primary end of a session, secondary end of a session, session connector.

A contiguous sequence of bits or characters that constitutes half a computer word and can be addressed as a unit. See also doubleword, fullword, word.

halfword binary
In DB2 for i5/OS, a binary number with a precision of 15 bits.

halfword boundary
A storage location whose address is evenly divisible by 2. See also word boundary.

halt indicator
In RPG, an indicator that stops the program when an unacceptable condition occurs. Valid halt indicators are H1 through H9.

An email message that does not contain advertising or inappropriate content.

Handheld Device Markup Language (HDML)
A specialized version of HTML designed to enable wireless pagers, cell phones and other handheld devices to obtain information from web pages.


  1. In application programming interfaces, a variable that represents an object, an instance of an application using some function, or a processing session.
  2. The portion of a message that contains control information.
  3. A variable that represents an internal structure within a software system.
  4. In the Java EE specification, an object that identifies an enterprise bean. A client may serialize the handle, and then later deserialize it to obtain a reference to the enterprise bean. (Sun)
  5. In DB2 ODBC, a variable that refers to a data structure and associated resources.
  6. A character string that is created by an extender that is used to represent an image, an audio, or a video object in a table. A handle is stored for an object in a user table and in administrative support tables. In this way, an extender can link the handle that is stored in a user table with information about the object that is stored in the administrative support tables.
  7. In WebSphere MQ, the identifier or token by which a program accesses an MQM object.
  8. A character string that represents an object, and is used to retrieve the object.
  9. In the AIX operating system, a data structure that is a temporary local identifier for an object. Allocating a handle creates it. Binding a handle makes it identify an object at a specific location.

handle cursor

  1. A pointer that keeps track of the current exception handler.
  2. A pointer used by the condition manager as it traverses the stack. The handle cursor points to the condition handler currently being invoked in the stack frame, whether it is a user-written condition handler or a condition handler specific to a high level language.

handled condition
A condition that either a user-written condition handler or the high-level language-specific condition handler has processed and for which the condition handler has specified that execution should continue. See also unhandled condition.

handle object
In IBM ILOG JViews, an object that is used to reference another object. Using handle objects, the same object can be displayed more than once without being duplicated.


  1. In web services, a mechanism for processing service content and extending the function of a JAX-RPC runtime system.
  2. An optional way of controlling the data source and adapters. The handler is responsible for handling requests that come from its associated graphic component that affect back-end data. See also equipment component, network component.
  3. In the CICS Front End Programming Interface (FEPI), a transaction initiated to handle specified events.
  4. A software routine that controls a program's reaction to specific external events, such as an interrupt handler.
  5. A function that is registered by the application programmer to be called by the system or by the application when certain events occur in the system or application.

handler class
Collection of functions that are called by the system or application when certain events occur in the system or application.

handling charge
An amount of funds charged to a buyer to cover the cost of shipping a product.

hand raise
An action that gets the meeting leader’s attention during a session. The user can click the “hand raise” button and then ask a question.

A feature that supports the use of a device without a handset. This capability is often implemented using Bluetooth technology.


  1. The exchange of messages at the start of a Secure Sockets Layer session that allows the client to authenticate the server using public key techniques (and, optionally, for the server to authenticate the client) and then allows the client and server to cooperate in creating symmetric keys for encryption, decryption, and detection of tampering.
  2. The exchange of predetermined signals when a connection is established between two data set devices.
  3. In Transport Layer Security (TLS), the initial setup of a TLS connection.

hand tuning
The process of modifying source code by hand to improve the performance of the resulting object code. Hand tuning is one aspect of optimization.

To become unresponsive to user commands and to stop or seem to stop processing.

See Hangul.

The Korean alphabet that consists of fourteen consonants and ten vowels. See also Jamo.

hang up
To terminate a call.

Korean characters derived from Chinese.

Term used in Taiwan for Chinese characters. See also Traditional Chinese.

HA policy
A set of rules that is defined for an HA group that dictate whether zero (0), or more members are activated. The policy is associated with a specific HA group by matching the policy match criteria with the group name.

hard address
The arbitrated loop physical address (AL_PA) that a node loop port (NL_port) attempts to acquire during loop initialization.

hard booking
The allocation of a resource that commits the resource to work on a project for its entire duration. Contoured work is placed in a planned state.

hard bundle
A bundle that contains additional serviceable units that are not part of separately sold products and that are not available outside of the bundle.

Pertaining to software instructions that are statically encoded and not intended to be altered.

The software development practice of embedding output or configuration data directly into the source code of a program or other executable object.

A printed copy of machine output in a visually readable form, such as printed reports, documents, and summaries.

hardcopy task (HCT)
In Tivoli NetView for OS/390, the subtask that controls the passage of data between the NetView program and the hardcopy device.

hard CPU shares
An attribute that defines the relative share of CPU resources on a host or LPAR that the WLM dispatcher allows a particular service class to use but not exceed, even if additional CPU resources are available.

hard disk
A nonremovable storage medium used for storage of data on a personal computer.

hard disk drive

  1. See drive.
  2. A stand-alone disk drive that reads and writes data on rigid disks and can be attached to a port on the system unit.

To write log data to the coupling-facility log structure and to either the buffer held in a data space or staging data sets.

hardened message
A message that is written to auxiliary (disk) storage so that the message is not lost in the event of a system failure.

The process of protecting security data from exposure to vulnerabilities by establishing restricted access to the data.

hard error
An error condition on a network that requires that the network be reconfigured or that the source of the error be removed before the network can resume reliable operation.

hard failure
See hard error.

hard font printer
A printer that uses a print technique in which the characters are physically engraved onto the print element.

hard link

  1. In a file system, an actual path to an existing object. A hard link is established by creating a directory entry. A hard link cannot cross file systems.
  2. A named connection between an object and its parent directory. An object may have multiple named connections between itself and one or more parent directories.

hard page segment
A page segment that is declared in the Map Page Segment structured field and loaded in the printer before printing begins. This resource can be reused during the job without being reloaded in the printer. Hard page segments can be controlled by a page segment list in a page definition. See also soft page segment.

hard reservation
A firm request for items from a storeroom that is defined by the need for the items within a specific time frame. A hard reservation reduces the available balance of items. Hard reservations are prioritized and cannot be superseded by other reservation types. See also soft reservation.

hard resource
A resource declared in the appropriate Map structured field and loaded in the printer the first time it is referenced. It can be reused during the job without being reloaded to the printer. See also soft resource.

hard space
See required space.

A function that halts the system without waiting for a business process to finish. Hard stops may result in loss of data in unfinished processes.

hard stop
A policy according to which, if a user starts the product and there are no licenses available, the product does not start.

hardware (H/W)
The physical components of a computer system. See also software.

hardware abstraction layer (HAL)
In operating systems such as Windows NT, a layer in which assembly language code is isolated. A hardware abstraction layer functions similarly to an application programming interface (API) and is used by programmers to write device-independent applications.

hardware cell
In the GDDM function, the default character box associated with a particular display.

hardware character
In the GDDM function, an alphanumeric character provided by the display station, usually from a display file.

hardware configuration
A set of parameters used to configure hardware before an operating system installation. It includes RAID settings, BIOS update information, BIOS settings, and custom hardware configuration parameters.

hardware configuration definition (HCD)
An interactive interface in z/OS that is used to define hardware configurations to the operating system and the channel subsystem.

hardware control point
The hardware device through which the management server controls node hardware.

hardware default font
The font used by the printer if no other font is specified.

Hardware Management Console (HMC)

  1. In a system storage environment, a system that acts as the focal point for configuration, management of Copy Services functions, and maintenance.
  2. An integrated platform management interface through which data center personnel configure, control, and monitor System z hardware and software resources and manage System z hardware resources. The HMC communicates with each central processor complex (CPC) through the Support Element (SE). See also alternate Hardware Management Console, primary Hardware Management Console.
  3. A system that controls managed systems, including the management of logical partitions and use of Capacity Upgrade on Demand. Using service applications, the HMC communicates with managed systems to detect and consolidate information, which is then sent to IBM for analysis. See also Capacity Upgrade on Demand, free pool, managed system.

Hardware Management Console Application (HWMCA)
A user-customized, object-oriented graphical user interface (GUI) that provides a single point of control for the system's hardware elements. The HWMCA provides aggregated and individual real-time system status using colors; consolidated hardware messages support; consolidated services support; and hardware commands targeted at a single system, multiple systems, or a group of systems.

hardware monitor
A monitor that collects and displays events and statistical data both for hardware and for software applications to identify failing resources in a network. For problem determination, it also provides probable cause information and recommended actions. See also session monitor.

hardware service manager (HSM)
A tool for displaying and working with system hardware from both a logical and a packaging viewpoint, for debugging input/output processors (IOPs) and devices, and for fixing failing and missing hardware.

hardware support (HWSUPPORT)

hardware system area (HSA)
A logical area of central storage, not addressable by application programs, used to store Licensed Internal Code and control information.

hardware zoning
A grouping of physical ports on a switch in a fabric. It can be implemented in the following configurations: one to one, one to many, and many to many. See also fabric.

In the Reusable Asset Specification (RAS), the activity of extracting reusable content, assets and architectures.

has components relationship
The type of relationship that indicates dedicated containment, such as a parent-child relationship among components in which the child components cannot be shared with other components. See also federates relationship, fixes relationship.


  1. In computer security, a number generated from a string of text that is used to ensure that transmitted messages arrived intact.
  2. An alphanumeric string that is generated from another value in order to aid in the searching and comparing of values within the entity database.

hash access
Access to a table that uses the hash value of a key that is defined by the organization-clause of a CREATE TABLE statement or ALTER TABLE statement.

hash code
Format in which data is stored in compressed form.

hashed message authentication code (HMAC)
A mechanism for message authentication using cryptographic hash functions. See also HOTP.

hashed method authentication code (HMAC)
A mechanism for message authentication that uses cryptographic hash functions.

hash function
A function that determines which category, or bucket, to put an element in. A hash function is needed when implementing a hash table.


  1. A method by which a large number of memory records are stored and can then be efficiently searched. This is accomplished through the use of a tailored index that organizes the memory records. This arrangement of records is called a hash table.
  2. The process of encoding a character string as a fixed-length bit string for comparison. The encoding may not necessarily be unique.
  3. A method of transforming a search key into an address for the purpose of storing and retrieving items of data.

hash join
A method for joining two or more files together that uses a hash value to find the matching keys.

hash overflow index
A DB2 index used to track data rows that do not fit into the fixed hash space, and therefore, reside in the hash overflow space. DB2 accesses the hash overflow index to fetch rows from the hash overflow area.

hash partitioning
A data distribution strategy in which a hashing algorithm is applied to a distribution key value to determine the database partition to which a row is assigned.

hash rule
A user-defined algorithm that maps each row in a table to a set of hash values and that is used to determine the fragment in which a row is stored.

hash table

  1. A data structure that divides all elements into (preferably) equal-sized categories, or buckets, to allow quick access to the elements. The hash function determines which bucket an element belongs in.
  2. A table of information that is accessed by way of a shortened search key (the hash value). The use of a hash table minimizes average search time.
  3. The arrangement of memory records.

In mobile computing, a phrase prefix that links content with other content about the same topic. For example, prefacing a tweet with "#Bills" groups a tweet in the Buffalo Bills subject group. See also social network, tweet.

hash value
A number that is generated from a string of text. The hash value (or simply hash), is substantially smaller than the text itself and is generated by a formula in such a way that is extremely unlikely that some other text will produce the same hash value. Hashes are used in security systems to ensure that transmitted messages have not been tampered with and also are used to access data records.

HA solution
See high availability solution.

See Houston Automatic Spooling Program.

A finishing item that consists of a series of parallel lines. The parallel lines are entered either at user-specified separations and angles or with a user-defined hatch pattern.

See Host Access Transformation Services.

HATS application
An application that presents a Web-enabled version of a host application to users. A HATS application is created in HATS Studio from a HATS project and deployed to WebSphere Application Server and/or interacts with other host applications or e-business applications to present combined information to an end user.

HATS EJB project
A project that contains enterprise beans made from Integration Objects that other applications can call to get host data. A HATS EJB project does not present transformed screens from a host application.

HATS entry servlet
The servlet that is processed when a user starts a HATS application.

HATS project
A collection of resources (also sometimes called "artifacts") created and customized in HATS Studio, which can be assembled into a HATS application.

HATS Studio
The component of HATS that runs on WebSphere Studio and enables users to work with HATS projects to create HATS applications.

HATS/WebFacing enabled project
A project that can be linked with a HATS project for the purpose of creating combined applications with full access to both WebFacing and HATS customization capabilities. See also linked HATS/WebFacing project.

hazardous character
A character which is used for performing web application attacks, such as XSS or SQL injection.

hazardous material
Material that has the potential to pose a safety hazard. This designation requires special handling and labeling as dictated through laws and regulations.

Hazardous Materials distance (HAZMAT distance)
A mileage type that calculates the distance based on government sanctioned hazardous material routes.

HAZMAT distance
See Hazardous Materials distance.

See host bus adapter.

See heuristic commit.

See host channel adapter.

See hardware configuration definition.

See Host Command Facility.

See 3270 Host Connection Program.

See host command processor.

HCP emulation
See host command processor emulation.

See hardcopy task.

See half-duplex.

See hierarchical direct access method.

See high-density bipolar of order 3.

See hard disk drive.

In AIX, a logical unit number (LUN) on an array.

See High-level Data Link Control.

See Handheld Device Markup Language.

HD organization
See hierarchic direct organization.

See host-discovered resource.

HDR snapshot
See snapshot.

See half-duplex.

See Host Ethernet Adapter.

A device that reads, writes, or erases data on a storage medium.

head and disk assembly
The portion of a hard disk drive (HDD) associated with the medium and the read/write head.


  1. See message header.
  2. Information related to a document and common to all details in the document. For example, on a customer order, the ship-to address in the header is common to all of the individual line items of that order and, therefore, not repeated for each individual line item.
  3. Text that is formatted to be in the top margin of printed pages in a document. See also footer.
  4. Control information prepended to data content that is normally used to describe the data or the relationship of the data with the applications.
  5. System-defined control information that precedes user data.
  6. In disk management, the 8-byte portion of the 520-byte disk sector used by the operating system for control and access information.
  7. See include statement.

header approval rule
A rule that can be applied to the quote header level. If all the conditions in the rule are met, a customer sales representative can apply the corresponding discount as a header level discount in the corresponding quote.

header banner
An optional report delimiter that contains recipient address information.

header file
See include file.

header fragment
The first fragment in a series of fragments.

header label
The label or data set label that precedes the data records on a unit of recording medium.

header page
A separator page that precedes a printed file or a print job. See also data set header, job header.

header record

  1. A record at the beginning of a file that details the sizes, locations, and other information that follows in the file.
  2. A record that contains information, such as customer name and customer address, that is common to detail records. See also detail record.
  3. In RPG, output records that are printed at the top of a report and include report titles, column headings, or any other data needed to identify the information in the report.

header remap service
A service that converts EDI envelopes from one type to another type within the same standard, where both the header and trailer segments are converted without changing the body of the data.

header segment
The first EDI segment in an envelope that contains a unique control number that identifies the envelope.

An artifact in a module that is automatically numbered and displayed prominently. A best practice is for headings to be their own artifact type.

Pertains to a program or application that can run without a graphical user interface or, in some cases, without any user interface at all. Headless operation is often used for network servers or embedded systems.

The general condition or state of the database environment.

health controller
An autonomic manager that constantly monitors defined health policies. When a specified health policy condition does not exist in the environment, the health controller verifies that configured actions correct the error.

health indicator
A measure of some aspect of the health of an object. Threshold-based health indicators identify whether the behavior of an object is within ranges of normal, warning, and alarm. State-based health indicators identify whether the state of an object is normal or non-normal. See also health monitor alert.

health information technology (HIT)
A technology, which includes a variety of integrated data sources, that is capable of capturing, analyzing, storing, and appropriately sharing information about an individual patient and patient populations.

Health Insurance Portability and Accountability Act
A legislative act in the U.S. that requires health plans and providers to use a common format when electronically communicating health information.

health monitor
An instance-level monitor that creates alerts based on a health indicator exceeding a threshold or being in non-normal state. The monitor sends notifications to the notification log and also sends emails and pages to contacts on its notification list.

health monitor alert
An alert that is generated by the health monitor and is based on the type of health indicator. See also health indicator.

health notification contact list
A set of contacts that receives notifications when health alerts occur.

health policy
A set of rules that an administrator can define and use to monitor conditions and take actions when the conditions occur.

health snapshot
Health data, retrieved from the database manager at a point in time, for a set of database objects.


  1. In Java programming, a block of memory that the Java virtual machine (JVM) uses at run time to store Java objects. Java heap memory is managed by a garbage collector, which automatically de-allocates Java objects that are no longer in use.
  2. An object that provides dynamic storage for a procedure. The object is part of the activation group and is deleted when the activation group is deleted.
  3. A collection of dynamically allocated variables.
  4. A logical grouping of memory that fulfills the needs of a particular component. For example, the utility heap memory is used by DB2 utilities such as backup, restore, and load.
  5. An area of storage that is allocated with a lifetime unrelated to the execution of the current routine. The heap consists of the initial heap segment and zero or more increments.

heap element
An area of contiguous storage that is allocated upon request from the user application. Heap elements are always allocated within a single heap segment. See also heap segment.

heap identifier
A number that identifies a heap within its activation group.

heap increment
The second and subsequent segments of storage allocated when the initial heap segment does not have enough free storage to satisfy a request for heap storage.

heap pool
A storage pool used by the storage manager to improve the performance of heap storage allocation. The use of heap pools can improve the performance of an application, especially multi-threaded applications.

heap segment
A contiguous area of storage obtained directly from the operating system. The Language Environment storage management scheme subdivides heap segments into individual heap elements. If the initial heap segment becomes full, Language Environment obtains a second segment, or increment, from the operating system. See also heap element.

heap space
A process space that provides dynamic storage for a procedure. The heap space is part of an activation group and is destroyed when the activation group is destroyed.

heap storage
An area of storage used for allocation of storage that has a lifetime that is not related to the execution of the current routine. The heap consists of the initial heap segment and zero or more increments.

A signal that one entity sends to another to convey that it is still active. See also heartbeat call-home record, Remote Technical Assistance and Information Network.

heartbeat call-home record
Machine operating and service information sent to a service machine. These records might include such information as feature code information and the logical-configuration information for a product. See also heartbeat.

heartbeat flow
A pulse that is passed from a sending message channel agent (MCA) to a receiving MCA when there are no messages to send. The pulse unblocks the receiving MCA, which would otherwise remain in a wait state until a message arrived or the disconnect interval expired.

heartbeat interval
The time, in seconds, that is to elapse between heartbeat flows.

heat map

  1. A graphical representation of data values in a two-dimensional table format, in which higher values are represented by darker colors and lower values by lighter ones.
  2. A color-coded data chart in which colors are used to differentiate values in a data set.

heavyweight thread
A type of thread that has a one-to-one correspondence with a task control block (TCB) in that the lifetime of the thread is the lifetime of the TCB.

A word used to qualify a fuzzy set in a fuzzy clause.

held state
The state of a connection that results in the connection being maintained after the next commit operation. This is the initial state of connections. See also released state.

See DCN Local-Network Protocol.

hello datagram
In NCP Internet Protocol (IP) support, an IP datagram that establishes and verifies communication between an NCP IP router and its IP owner.

hello message
A message sent periodically to establish and test reachability between routers or between routers and hosts.

Hello Protocol
A protocol used by OSPF systems for establishing and maintaining neighbor relationships.

A choice that gives a user access to helpful information about objects, choices, tasks, and products. A help choice can appear on a menu bar or as a push button.

A program used by the INed editor to provide extra functions for a particular type of data file.

help file
A file, separate from the source code of a program, that contains help definitions in a special help format that Base Operating System message services can use.

help key
A function key that a user presses to get information about menus, prompts, or messages.

help level specification
In a display file, data description specification coded between the record and field level that defines areas on the screen and associates help information with those areas.

help module
In user interface manager, the smallest part of a panel group object that can be displayed separately. A help module can be used for contextual help, extended help, or a hypertext node.

help panel
A screen of information that presents tutorial text to assist a user at a workstation or terminal.

hertz (Hz)
A unit of frequency equal to one cycle per second.

See variability.

heterogeneous commit
A protocol governing a group of database servers, of which at least one is a gateway participant. A heterogeneous commit ensures the all-or-nothing basis of distributed transactions in a heterogeneous environment.

heterogeneous computer network
A computer network in which computers have dissimilar architecture, but nevertheless are able to communicate.

heterogeneous network
In MPTN architecture, a single logical network formed by MPTN gateways that join individual networks that support different transport protocols.

Heterogeneous Workload Management
A core capability of the IBM Autonomic Computing Initiative that addresses the need to definitively determine the cause of a bottleneck in a complex system, including response time measurement and transaction processing.


  1. A guideline that a system administrator uses to intervene where the two-phase commit or abort would otherwise fail.
  2. An optimizer processing technique that is used to consolidate orders and shipments into larger, more cost-effective loads.

heuristic commit (HC)
A decision to commit some, but not all, of the protected resources in an ACID transaction.

heuristic damage
The inconsistency in data between one or more participants that results when a heuristic decision to resolve an indoubt LUW at one or more participants differs from the decision that is recorded at the coordinator.

heuristic decision

  1. A decision made by a user to commit or roll back a transaction on a DB2 database.
  2. A decision to force a commit or rollback of a logical unit of work in part of a transaction program network that is using the two-phase commit protocol. A heuristic decision is made when a system or communication failure prevents the logical unit of work from being completed.
  3. A decision that forces indoubt resolution at a participant by means other than automatic resynchronization between coordinator and participant.

heuristic mixed
Pertaining to an inconsistent state of resources in an ACID transaction when some resources were committed and some resources were backed out.

heuristic reset
The decision to back out some, but not all, of the protected resources in a transaction.

See hexadecimal.

hexadecimal (hex)
Pertaining to a numbering system that has a base of 16.

hexadecimal constant
A constant, usually starting with special characters, that contains only hexadecimal digits.

hexadecimal literal
A literal that specifies a column value in a column map or relationship, when the corresponding column contains binary data.

hexadecimal string
In REXX, any sequence of zero or more hexadecimal digits (0-9, a-f, or A-F), optionally separated by blanks, delimited by apostrophes or quotation marks, and immediately followed by the symbol x or X.

See hierarchical file system.

HFS data set
See hierarchical file system data set.

HFS file
An object that exists in a mountable file system.

HHG distance
See Household Goods distance.

See System/370 Host Interface Adapter.

hibernating policy activator
A service that is responsible for waking hibernating policies.

See hierarchical indexed direct access method.

hidden address
An address that is mapped to another address. The method of mapping that is used does not allow external systems to initiate communications with hidden addresses unless port numbers are specified.

hidden data node
A child of a collapsed parent node, not represented by a row in a Gantt or schedule chart. See also displayed data node.

hidden field
A field in a display file that is passed to and from the program but is not sent to the display.

hidden file
An operating system file that is not displayed by a directory listing. The name of a hidden file usually begins with a period.

hidden parameter
An HTML form parameter that is not rendered in the web page.

hidden surface
The surface of a geometric primitive that is not visible because it is obscured by other surfaces.

hidden task node
A navigation node that launches a page that does not render a tab in the page bar. While a hidden node is open, the page bar is disabled.

hidden widget
A fully functional widget that transforms business data so that another widget can use this data. A hidden widget is not displayed on a page, unless all widgets are displayed. When a hidden widget is made visible, the widget has a dashed frame.

hide function
In AFP Utilities, a function on the screen view used to display elements hidden by other elements that were specified after the hidden elements and in the same or approximate position as the hidden elements.

Pertaining to data that is organized on computer systems using a hierarchy of containers, often called folders (directories) and files. In this scheme, folders can contain other folders and files. The successive containment of folders within folders creates the levels of organization, which is the hierarchy.

hierarchical business object
A business object that contains one or more child business objects. See also flat business object, top-level business object.

hierarchical choice list
A grouping of choice list values usually presented as cascading menu options.

hierarchical CSM
A tiered Cluster Systems Management (CSM) environment in which a top-level executive management server (EMS) manages mid-level first-line management servers (FMS).

hierarchical data
Data that is organized on computer systems using a hierarchy of containers.

hierarchical direct access method (HDAM)
A database access method using algorithmic addressability to records in a hierarchic direct organization. A choice of OSAM or VSAM ESDS is available as a base for HDAM.

hierarchical file system (HFS)

  1. A part of the i5/OS operating system that includes the application programming interfaces and the underlying file system support. HFS enables an application written in a high-level language to create, store, retrieve, and manipulate data on a storage device. The view of the data to the user is a hierarchical directory structure similar to DOS.
  2. A system for organizing files in a hierarchy, as in a UNIX system.

hierarchical file system data set (HFS data set)
A data set that contains a particular type of file system that is compliant with the Portable Operating System Interface (POSIX). An HFS data set is a collection of files and directories organized in a hierarchical structure that can be accessed using z/OS UNIX System Services (z/OS UNIX).

hierarchical indexed direct access method (HIDAM)
A database access method used for indexed access to records in a hierarchic direct organization. It provides indexed access to the root segments and pointer access to subordinate segments.

hierarchical indexed sequential access method (HISAM)
A database access method used for indexed access to records in a hierarchic sequential organization.

hierarchical loop (HL)
A technique for describing the relationship of data entities which are related in a parent to child manner, like a corporate organization chart.

hierarchical naming
A system of naming that reflects the relationship of names to the certifiers in an organization. Hierarchical naming helps distinguish users with the same common name for added security and allows for decentralized management of certification. The format of a hierarchical name is: common name/organizational unit/organization/country code -- for example, Pam Tort/Fargo/Acme/CA.

hierarchical network
A network in which hosts are administered by a tree structure of authority. This network structure relieves the administrative burden of the central authority.

hierarchical property
An extended rule property whose values are organized into a hierarchy.

hierarchical storage management (HSM)
A function that automatically distributes and manages data on disk, tape, or both by regarding devices of these types and potentially others as levels in a storage hierarchy that range from fast, expensive devices to slower, cheaper, and possibly removable devices. The objectives are to minimize access time to data and maximize available media capacity. See also hierarchical storage management client, recall, storage hierarchy.

hierarchical storage management client (HSM client)
A client program that works with the server to provide hierarchical storage management (HSM) for a system. See also hierarchical storage management, management class.

hierarchical view
In Notes, a view that distinguishes between main documents and response documents. Each main document has its response documents indented under it.

hierarchic direct organization (HD organization)
The physical storage organization in which database segments that represent a physical database record are related by direct address pointers in the segment's prefix.

hierarchic sequence
In a database, the sequence of segment occurrences in a database record defined by traversing the tree top to bottom, front to back, and left to right.

hierarchic sequential organization (HS organization)
The physical storage organization in which database segments that represent a physical database record are related by adjacency.


  1. In publish/subscribe messaging topology, a local queue manager connected to a parent queue manager.
  2. The tree-like arrangement of segments in a database, beginning with the root segment and proceeding down to dependent segments.
  3. A structure that has a predetermined ordering from high to low.
  4. A particular view of a business dimension. A hierarchy contains the definition of related reference data that is organized into a tree structure of members related as parents and children.
  5. A type of container that is a hierarchical collection and classification of data. Hierarchies are made up of categories and items. Types of hierarchies include category hierarchies and organization hierarchies. See also category, container.
  6. In COBOL, a set of entries that includes all subordinate entries to the next equal- or higher-level number.
  7. A defined relationship among a set of attributes that are grouped by levels in the dimension of a cube model.
  8. The organization of a set of entities into a tree structure, with each entity (except the root) having one or more parent entities and an arbitrary number of child entities.

hierarchy of parts
A tree structure that defines the superior and subordinate EGL parts at definition time, as reflected in any of three kinds of EGL files.

high availability (HA)

  1. Pertaining to a clustered system that is reconfigured when node or daemon failures occur so that workloads can be redistributed to the remaining nodes in the cluster. See also application tier.
  2. The ability of IT services to withstand all outages and continue providing processing capability according to some predefined service level. Covered outages include both planned events, such as maintenance and backups, and unplanned events, such as software failures, hardware failures, power failures, and disasters. See also fault tolerance, high availability solution.

High Availability Control Workstation (HACWS)
A function based on High-Availability Cluster Multi-Processing (HACMP) that provides a backup control workstation.

high-availability data replication
A synchronous method of data replication that is used to maintain a backup copy of the entire database server that applications can access quickly in the event of a catastrophic failure.

high availability disaster recovery (HADR)
A disaster recovery solution that uses log shipping and provides data to a standby system if a partial or complete site failure occurs on a primary system. See also asynchronous mode, log shipping, Q replication, standard database, standby database, super asynchronous mode.

high availability file system
A cluster file system that can be used for component redundancy to provide continued operations during failures.

high availability large database (HALDB)
A partitioned full-function DL/I database. The supported database organizations are PHDAM, PHIDAM, and PSINDEX.

high availability licensing
A type of licensing in which a cluster of network license servers jointly serve concurrent licenses, with one or more servers in reserve in case a server goes down.

high availability manager
A framework within which core group membership is determined and status is communicated between core group members.

high availability solution (HA solution)
A combination of hardware, software, and services that fully automates the recovery process and does not disrupt user activity. HA solutions must provide an immediate recovery point with a fast recovery time. See also high availability.

high-capacity input station
A transfer station used by the operator to add tape cartridges to the Automated Tape Library Dataserver (ATLDS), which is inside the enclosure.

high-capacity output station
A transfer station used by the operator to remove tape cartridges from the Automated Tape Library Dataserver (ATLDS), which is inside the enclosure.

high-density bipolar of order 3 (HDB3)
An E1 line coding method in which each block of four successive zeros is replaced by 000V or B00V, so that the number of B pulses between consecutive V pulses is odd. Therefore, successive V pulses are of alternate polarity so that no dc component is introduced. Note: B represents an inserted pulse conforming to the alternate mark inversion rule and V represents an AMI violation. HDB3 is similar to B8ZS used with T1.

high-end device
A fully-featured mobile device. For example, an Apple iPhone or a BlackBerry Torch. See also entry-level device.

higher layer
The conceptual level of control or processing logic existing in the hierarchical structure of a station that is above the link layer and upon which the performance of data link functions are dependent (for example: device control, buffer allocation, station management).

higher level
See higher layer.

highest return code
A numeric value in the range of 0 - 4095. If this return code is exceeded during job processing, the job will be reported as ended-in-error.

High Level Assembler
An IBM licensed program that translates symbolic assembler language into binary machine language.

High-level Data Link Control (HDLC)
A form of communications line control that uses a specified series of bits rather than control characters to control data transmission over a communications line.

high-level language (HLL)
A programming language that provides some level of abstraction from assembler language and independence from a particular type of machine.

high-level language application programming interface (HLLAPI)
A programming interface that usually operates in conjunction with an emulator, such as 3270 emulation, and allows interaction using 3270 data stream between a host and a remote application program.

high-level language pointer (HLL pointer)
A source pointer that the programmer declares in the user program.

high-level programming language
A programming language that does not reflect the structure of any particular computer or operating system. Examples are APL, BASIC, C, and COBOL.

high-level qualifier (HLQ)
A qualifier that groups tables together with other tables that have different names, but the same qualifier.

To emphasize a display element or segment by changing its visual attributes.

Emphasis associated with displayed or printed information, such as font changes, overstriking, underscoring, capitalization, increased intensity, or color.

Pertaining to the most significant, or leftmost, item in a representation. For example, bit 0 in a register is the high-order bit.

high-performance computing (HPC)
A technology that requires massive computational powers, such as supercomputers or computer clusters, to solve complex problems.

high-performance data transfer services
In VTAM, a family of functions that enhances the efficiency of large message transfers for VTAM application programs.

high-performance file system (HPFS)
In PC operating systems, an installable file system that uses high-speed buffer storage, known as a cache, to provide fast access to large disk volumes. The file system also supports the coexistence of multiple, active file systems on a single personal computer, with the capability of multiple and different storage devices.

high-performance optical file system (HPOFS)
An IBM-developed media-format architecture that is available when initializing optical media. This media format is required for Write Once Read Many (WORM) media, and it is the default media format when initializing erasable optical media.

high-performance option (HPO)
An option provided with MVS to improve performance by reducing the transaction pathlength; that is, the number of instructions needed to service each request.

High-Performance Parallel Interface (HiPPI)
An ANSI-standard, high-speed, connection-oriented, communication channel. It is used primarily to connect supercomputers and as a high-speed LAN.

High-Performance Routing (HPR)
An addition to APPN that enhances data-routing performance and session reliability.

high-performance transmission subsystem (HPTSS)
A high-speed line adapter that attaches to the IBM 3745 Communication Controller.

high private area
Part of the CICS address space, consisting of the local system queue area (LSQA), the scheduler work area (SWA), and subpools 229 and 230. The area at the high end of the CICS address space is not specifically used by CICS, but contains information and control blocks that are needed by the operating system to support the region and its requirements. See also local system queue area.

high speed data entry (HSDE)
A method of entering data in which the cursor automatically moves to the next field where the next bar code needs to be scanned, thus eliminating the need for a keystroke by the operator.

high-speed line
A communications line that transmits at speeds greater than 19,200 bits per second.

high-speed link (HSL)
A hardware connectivity architecture that links system processors to system I/O buses and other systems. See also remote input/output.

high-speed link loop
The system-to-expansion-unit connectivity technology that is required to implement switchable independent disk pools residing on an expansion unit. The servers and expansion units in a cluster that uses resilient devices on an external expansion unit must be on an HSL loop that is connected with HSL cables.

high-speed link ring (HSL ring)
A logical ring of HSL connections originating from the HSL controller of a processor unit, sequentially connecting I/O or other processor units and ending back at the HSL controller where the ring originated.

High-Speed Packet Access (HSPA)
An upgrade to 3G phone networks. HSPA networks differ from many other mobile networks in that they provide both efficient data services and efficient voice services. See also 3G, Evolved High-Speed Packet Access.

high-speed sequential processing (HSSP)
An option, available only to batch message programs, for optimizing the sequential processing of DEDB areas. A simultaneous image copy can also be created.

high threshold of occupancy
In DFSMShsm, the upper limit of space that can be occupied on a volume managed by DFSMShsm.

high-water mark
The highest value reached in a set of readings taken over a period of time.

high watermark

  1. The highest number of cuncurent sessions reached over a specified time period.
  2. The maximum number of soft stop licenses that have been granted for a given product, over the number of licenses enrolled for that product.

high watermark setup (HWS)
A method to allocate a minimum number of unique device types that fulfill the requirements for each job step. Devices used in one step can be released and used again in later steps.

hijacked file
A version of an element in a snapshot view or a web view that is modified but not checked out.

Hindi numeral
Any of the set of numerals used in many Arabic countries instead of, or in addition to, the Arabic numerals. Hindi numeral shapes are ?????????, which correspond to the Arabic numeral shapes of 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9, respectively. See also Arabic numeral, Chinese numeral, number, Roman numeral.

An extension to both the queued sequential access method (QSAM) and the Virtual Storage Access Method (VSAM) designed to improve performance. Hiperbatch uses the Data Lookaside Facility to provide an alternate fast-path method of making data available to many batch jobs.

A System z hardware feature that provides high performance internal communications between logical partitions (LPARs) within the same central processor complex (CPC) without the use of any additional or external hardware equipment such as a channel adapter.

A high-performance, virtual-storage space of up to 2 gigabytes (GB). Unlike an address space, a hiperspace contains only user data and does not contain system control blocks or common areas; code does not execute in a hiperspace. Unlike a data space, data in a hiperspace cannot be referenced directly; data must be moved to an address space in blocks of 4 KB before being processed.

hiperspace memory file
A type of file that is stored in a single buffer in an address space, with the rest of the data being kept in a hiperspace. In contrast, for regular files, all the file data is stored in a single address space.

See High-Performance Parallel Interface.

One of the two common Japanese phonetic alphabets (the other is katakana). The symbols are cursive or curvilinear in style. Hiragana syllables are typically used in the representation of native Japanese words and grammatical particles. See also Kanji, Katakana.

See hierarchical indexed sequential access method.


  1. In Performance Tools, a bar graph used in the performance advisor to display the variations over time of one type of data in a performance data collection.
  2. In the GDDM function, a chart in which each value of the dependent variable corresponds to a range of values of the independent variable (represented by the width of the associated bar). For example, such a chart might display the number of people in various age ranges.
  3. A graphical display of the distribution of values for a numeric field, in the form of a vertical bar chart in which taller bars indicate higher values.

histogram statistics
A technique for summarizing data distribution that divides the range of possible values in a data set into intervals, such that each interval contains approximately the same percentage of the values. A set of statistics are collected for each interval.

historical cost
See baseline unit cost.

historical inventory
A set of files that contain information about Infoprint Server print jobs that are no longer on the JES spool. These print jobs finished processing or were deleted from the JES spool. Infoprint Central can display information about print jobs in the historical inventory.

historical row
A row in a history table. See also history table.


  1. Metadata in a versioned object base (VOB) that consists of event records for objects in that VOB.
  2. The recorded changes to modules and objects, which can be viewed on module and object properties sheets.

history file
A file in which a record is kept of shell commands that are executed.

history load
A collection of line items from orders organized in a way to maximize shipping efficiency.

history log

  1. A file that keeps a record of activities for a workflow.
  2. A summary of the system activities, such as system and job information, device status, system operator messages, and a record of program temporary fix (PTF) activity on the system. The history log is identified by the name QHST, and the system-recognized identifier for the object type is *MSGQ.

history table
A table that is used by the database manager to store historical versions of rows from the associated system-period temporal table. See also historical row, system-period temporal table.

See health information technology.

An object that associates an index to every pixel. Pixels with the same index behave the same way in interactions. This approach enables pure client-side interaction capabilities in JViews Web applications without requiring roundtripping to the servers. Highlighting and tooltips are typical interactions that can be performed using hitmap technology.

hitmap information
The collection of all region information for a hitmap. See also region.

hit testing
A test that maps from a given display point to an object to determine if the point is part of the object space.

See hierarchical loop.

See high-level language.

See high-level language application programming interface.

HLL pointer
See high-level language pointer.

See high-level qualifier.

See home location register.


  1. See hashed method authentication code.
  2. See hashed message authentication code.

See Hardware Management Console.

HMC 5250 console
An emulation session to a logical partition's operating system.

hog factor
In system accounting, an analysis of how many times each command was run, how much processor time and memory it used, and how intensive that use was.


  1. To keep an interface item pressed for approximately two seconds or longer. Typically, apps use hold gestures as part of a drag gesture. See also gesture.
  2. An order status that prevents certain modification types and transactions from processing the order or order line until the hold is released.
  3. A function that protects a cell against breakback.
  4. A method of stopping the normal disposition of a record, usually because of court cases or investigations.

holdable result set
A result set that is associated with a cursor that was created with the WITH HOLD clause.

hold cursor
A special type of cursor which is not closed at the end of a transaction. The database server still closes all other cursors, and it still releases all locks, but the hold cursor remains open until it is explicitly closed.

hold delivery
The method of delivering messages to a message queue that holds the messages until the user requests them. The user is not notified when a message arrives.

hold queue
A logical queue in the transmission control queue that contains processes waiting for operator intervention before they move to the wait queue for scheduling.

hold sweep
A daemon process that finds records meeting the conditions needed to place them on hold.

hold type
In Sterling Order Management overrides, the type of hold placed on an order when a violation is logged against it. The hold type is determined by the applicable validation domain.

A row of a result table that cannot be accessed because a delete operation or an update operation has been performed on that row. See also delete hole, update hole.

holidays calendar
The default non-working days calendar for all job streams. A holidays calendar must be created and named "holidays", otherwise the default non-working days are considered to be all Saturdays and Sundays. See also calendar, non-working days calendar.

home address
A field at the beginning of a track that contains information that identifies the physical track and its association with a cylinder. See also track.

home address space

  1. The area of storage that z/OS currently recognizes as dispatched.
  2. The address space in which MVS initially dispatches a work unit. When MVS initially dispatches a work unit, the home address space, the primary address space, and the secondary address space are the same. During execution of the work unit, the home address space remains the same, but the primary and secondary address spaces can change.

home cell
See local cell.

home database
A database where a partition definition is created. This is the database where the master copy of the data is stored.

home directory
The current directory associated with the user at the time of login.

home host
The host on which a member is created and on which that member typically runs.

home interface
In enterprise beans, an interface that defines zero or more create and remove methods for a session bean or zero or more create, finder, and remove methods for an entity bean. See also remote interface.

home location

  1. In Backup, Recovery, and Media Services, the storage location where available media is stored awaiting reuse. Typically, this is the on-site tape inventory.
  2. In DFSMSrmm, the location to which DFSMSrmm normally returns a volume when the volume is no longer retained by vital records processing.

home location register (HLR)
A database in a cellular system that contains all the subscribers within the provider's home service area.

home menu
The menu that is displayed if the user presses the Home key while the cursor is in the home position of a menu.

home method
A method in the home interface that is used by a client to create, locate, and remove instances of enterprise beans.

home node

  1. The highest priority node for a resource group. The home node is the first node that is listed in the default node list for any nonconcurrent resource group.
  2. The node from which an application developer compiles and runs a program. The home node can be any workstation on the LAN.

home page

  1. The top-level web page of a portal.
  2. The initial web page that is returned by a website when a user specifies the URL for the website. Essentially, the home page is the entry point for accessing the contents of the website.

home position

  1. The first item in a list or the first line of help information.
  2. The position (farthest left) to which the print head moves after the printer is turned on and the Stop or Reset button is pressed.
  3. In System i Access, the first position of the first input field on the display.

home session
In CDE, a choice at logout to designate a particular session, other than the one you are currently in, as the one you will automatically return to at the next login. See also current session.

home submap
In NetView for AIX, the first submap that appears when a map is opened. Each map has a home submap. When new maps are created, the home submap is the root submap.

home system
The first system in a chain of systems that are linked by any combination of TELNET and pass-through requests.

homogeneous coordinates
A four-dimensional method of representing three-dimensional space. A point (x, y, z, w) in homogeneous coordinates is used to represent a point (X, Y, Z) in three-dimensional space by taking X=x/w, Y=y/w, and Z=z/w.

homogeneous rule
A rule for which the conditions are written on the same type and number of objects.

The process of getting a telephony product approved and certified by a country's telecommunications authority.

Hong Kong S.A.R. of China
See Hong Kong S.A.R. of the PRC.

Hong Kong S.A.R. of the PRC
Official name of the place known as Hong Kong.

Prefix or suffix indicating social status that is either attained by a person or conferred upon a person. See also qualifier, title.


  1. A location in a compiled program where the compiler has inserted an instruction that allows programmers to interrupt the program (by setting breakpoints) for debugging purposes.
  2. An empty script in which code can be entered.

hook flash
A signal sent to a switch to request a switch feature (such as call transfer).

hook ID
A unique number assigned to a specific trace point. All trace entries include the hook identifier of the originating trace point in the trace entry header. A hook ID is a 12-bit value. For user programs, the hook ID may be a value from 0x010 to 0x0FF. Hook identifiers are defined in the /usr/include/sys/trchkid.h file.

One segment of a transmission path between adjacent nodes in a routed network.

hop count
A measure of the links between two systems on a network. A hop count of 5 means that four gateways separate the source and destination machines.

hop count limit
In the IBM Token-Ring Network, the maximum number of bridges through which a frame may pass on the way to its destination.

hop count metric

  1. The number of host-to-host connections in a route.
  2. In a gateway, an indication that the next string represents the hop count to the destination host or network.

hop data
A packet of data transferred from one system to another that describes context about some earlier processing. Transaction tracking has two types of hop data: origin data and previous hop data.

Pertaining to data that is tracked between applications in a domain. See also vertical.

horizontal clustering
A topology that allows a single application to span several machines while presenting a single system image. See also cluster environment, vertical clustering.

horizontal context
A method of identifying a transaction flow within a transaction which is used to group interactions based on the application supplying the tracking data.

horizontal dimension
See page display.

horizontally displayed records
Subfile records that are grouped so that each line on the display shows more than one record of the same record format.

horizontal scaling
A topology in which more than one application server running on multiple computing nodes is used to run a single application.


  1. In TCP/IP, any system that has at least one IP address associated with it.
  2. A workstation required by extended agents. It can be any Tivoli Workload Scheduler workstation except another extended agent.
  3. In a cooperative processing environment, the system running the server program with which the CoOperative Development Environment/400 session communicates.
  4. In performance profiling, a machine that owns processes that are being profiled. See also server.
  5. The controlling or highest-level system in a data communications configuration.
  6. A computer that is connected to a network and that provides an access point to that network. The host can be a client, a server, or both a client and server simultaneously. See also client, server.

Host Access Transformation Services (HATS)
An IBM software set of tools that provides web-based access to 3270 and 5250-based applications and data sources.

host adapter
A physical subunit of a storage server that provides the ability to attach to one or more host I/O interfaces.

host address
See IP address.

host application
An application residing on the host computer.

host-based computer
In a computer network a computer that provides users with services such as computation and databases, and that usually performs network control functions.

host-based project
In zIDE, a project that has been defined on a z/OS system and can be downloaded to the workstation when connected to the remote system.

host bay
The physical space used for installing host adapters. The ESS has multiple host bays, with an equal number of bays assigned to each cluster.

host bus adapter (HBA)
An interface card that connects a host bus, such as a peripheral component interconnect (PCI) bus, to the storage area network.

host-centric application
In VisualAge RPG, an application in which the user's program logic is stored and run on the host.

host channel adapter (HCA)
Based on InfiniBand technology, a port connection on a system allowing a network fabric interconnect.

host command
In CoOperative Development Environment/400, a command processed on a host system. It can be sent from the host emulation window or from the AD/Cycle CoOperative Development Environment session.

Host Command Facility (HCF)
A feature available on a System/370, 43xx, or 30xx host system that enables a user on the host system to use applications on a System i system or other systems as if they were using remotely attached 5250-type display stations.

host command processor (HCP)
The SNA logical unit of the programmable store system store controller.

host command processor emulation (HCP emulation)
A function of the Point-of-Sale Utility licensed program that allows the System i system to appear to the host command processor (HCP) in a point-of-sale system as if the System i system were the System/370 host system.

host computer
In a computer network, a computer that provides services such as computation, database access, and network control functions.

host connection properties file
In Enterprise Service Tools, the resource in a service flow project that contains the information necessary to connect to the host system during build time, and to capture screens and record screen operations files. The host connection properties file also stores configuration properties that define the connection to the Enterprise Information System (EIS) at run time.

host-discovered resource (HDR)
A set of storage hardware resources that are attached to a host system and are available on the operating system.

host editor
In Enterprise Service Tools, an editor that a software developer uses to interact with the EIS application as a user of that application and to record one or more action sets (navigational keystrokes) for each description.

hosted partition
A logical partition that is dependent on another logical partition for I/O resources. The I/O resources that a hosted partition can share include disk, CD, and tape devices.

hosted private cloud
A cloud computing environment that is owned and operated by the same company. The customer owns and pays for infrastructure and has unlimited exclusive access.

Host Ethernet Adapter (HEA)
A physical Ethernet adapter that is integrated directly into the GX+ bus on a managed system. HEAs offer high throughput, low latency, and virtualization support for Ethernet connections.

host expression
A Java variable or expression that is referenced by SQL clauses in an SQLJ application program.

host group
See host.

host ID

  1. A numeric identifier assigned to a group of host Fibre Channel ports for the purpose of logical unit number (LUN) mapping. For each host ID, there is a separate mapping of Small Computer System Interface (SCSI) IDs to volumes.
  2. The unique identification of a host within an address family on a network, but without the network identification. A host ID is not necessarily sufficient to establish communications with a host.
  3. In TCP/IP, that part of the Internet address that defines the host on the network. The length of the host ID depends on the type of network class (A, B, or C).

host identifier
A name that is declared in the host program.

hosting application
A software application that acts as a containing environment for another software application. For example, a servlet engine is a hosting application for a servlet.

hosting domain
A root managed resource that provides manageability interfaces to the multiple indirect managed resources that are associated with it. For example, a messaging server, along with the queue managers and queues that are its indirect managed resources, is a hosting domain. See also direct managed resource, indirect managed resource.

hosting environment
A type of managed resource that acts as a container for a set of hosted managed resources throughout their lifetime. See also change manager, installable unit, smallest installable unit.

hosting partition
Either the primary or a secondary partition that is not a guest partition. The hosting partition has the real I/O devices that the virtual I/O device drivers in a guest partition connect to. The hosting partition also supplies the guest partition's DST console session, via a TELNET connection into the hosting partition. The guest partition's console is not part of the hosting partition's console. The host partition's console, the guest partition's console session and the guest partition's operating system's console are all different console sessions.

hosting requirement
A prerequisite that is met by a hosting application.

host interface card
An optional part of a node canister that provides the system with additional host and storage connectivity options.

host interface module
The part of the system rack containing the host interface HBAs and manager software.

host keypad
A set of buttons or links representing functions typically available from a host keyboard, such as function keys or the Enter key. See also application keypad.

host language
Any programming language in which SQL statements or XQuery expressions can be embedded.

host list
A comma-separated-value list of hosts used to add large numbers of hosts to the provisioning server without having to start the hosts individually on the network.

host list file
A file that contains a list of host names, and possibly other information, that were defined by the application that reads it.

host LU
In SNA, a logical unit in a host processor; for example, a VTAM application program.

hostmap file
See host name mapping file.

host mapping
The process of controlling which hosts have access to specific volumes within a clustered system.

host master key
In Cryptographic Support, a type of key-encrypting key used to encrypt data-encrypting keys and whose variants are used to encrypt all other key-encrypting keys stored on the system.

host master-key variant
In Cryptographic Support, a key-encrypting key derived from the host master key that is used to encrypt a certain type of cross-domain key.

host-mixed encoding scheme
An encoding scheme that contains a mixture of single-byte EBCDIC code pages and double-byte host code pages. A 5026 encoding scheme, for example, is CP290 (single byte) and CP300 (double byte).

host name

  1. The network name for a network adapter on a physical machine in which the node is installed.
  2. In Internet communication, the name given to a computer. The host name might be a fully qualified domain name such as mycomputer.city.company.com, or it might be a specific subname such as mycomputer. See also fully qualified domain name, IP address, network address.

host name mapping file
A file containing a list of host names and associated hardware control information.

host namespace profile
A profile that contains information about the list of hosts and their properties, such as host IP addresses and host aliases.

host node

  1. In SNA, a subarea node that contains a system services control point (SSCP), for example, an IBM System/390 computer with MVS and VTAM.
  2. A node that provides an application programming interface (API) and a common application interface.

host object
A logical object that represents a list of worldwide port names (WWPNs) and a list of iSCSI names that identify the interfaces that the host system uses to communicate with a device. iSCSI names can be either iSCSI qualified names (IQNs) or extended-unique identifiers (EUIs).

host platform server
A physical server that has hosting capabilities for virtual servers.

host print transform (HPT)
An i5/OS print function that converts an SNA character string (SCS) data stream into an ASCII data stream. The conversion enables consistent ASCII printing through hardware connections.

host processor

  1. A processor that controls a user application network.
  2. The primary or controlling computer in a multiple computer installation.

host program
An application program that is written in a host language and that contains embedded SQL statements or XQuery expressions.

host resource
A resource found either in a system library, in a user library, or inline in the print data set.

host server
Any computer on a network that is a repository for services available to other computers on the network.

hosts relationship
A relationship that indicates the component only applies to a specific hosting environment.

host stack
The collection of software that runs from the driver through the middleware and that provides the communications fabric protocols to be used by applications.

host structure
In an application program, a structure that contains a list of host variables that can be referred to by embedded SQL statements.

host subsystem
The processing unit of a node computer that runs local real-time applications.

host system

  1. See host.
  2. An enterprise mainframe computer system that hosts 3270 applications. In the 3270 terminal service development tools, the developer uses the 3270 terminal service recorder to connect to the host system.
  3. A computer, either mainframe (S/390 or zSeries) or open-system, that is connected to the ESS. S/390 or zSeries hosts are connected to the ESS through ESCON or FICON interfaces. Open-systems hosts are connected to the ESS by the Small Computer System Interface (SCSI) or the Fibre Channel interface.

host table
A list of host names and associated Internet Protocol (IP) addresses for an Internet Protocol (IP) network.

host terminal
A HATS Studio tool. A session tied to a particular HATS connection, which the HATS developer can use to capture screens, create screen customizations, and record macros.

host transit time
The average time (in seconds) that all transactions spend in the host. The time includes both VTAM and application time. It is also reported as an average for the transactions that originate at the logical unit for which data collection is occurring.

host variable

  1. A program data area that provides value to or receives value from a column in an SQL table.
  2. In an application program, a variable that is referred to by embedded SQL statements. Host variables are programming variables in the application program and are the primary mechanism for transmitting data between tables in the database and application program work areas.
  3. In an application program, a programming variable that is referred to by embedded SQL statements. The value of the host variable comes from the host program when a statement is executed or a cursor is opened. A host variable is a colon followed by a name (:name). See also parameter marker.

host variable array
An array of elements, each of which corresponds to a value for a column. The dimension of the array determines the maximum number of rows for which the array can be used.

host volume
A volume that represents the volume functional role from an application point of view. The host volume can be connected to a host or server. It receives read, write, and update application I/O, depending on the site to which the application is writing.

host zone
A zone that is defined in the storage area network (SAN) fabric in which the hosts can address the system.

hot backup

  1. In a remote journal network, pertaining to the function of replicating an application's dependent data from one primary System i product to a backup System i product. If the primary system fails, processing can be performed on the backup system.
  2. For programs that are running or resident on a backup systems, a configuration in which a copy of the program is installed for backup purposes, started, and actively doing work such as applying journaled database transactions. See also cold backup, warm backup.

hot deployment
The process of adding new components to a running server without stopping and restarting the application server or application. See also dynamic reloading.

hot directory
See monitored directory.

hot key

  1. A keystroke or a combination of keystrokes pressed simultaneously that activate or toggle a specific mode. For example on a bidirectional keyboard (such as an Arabic or a Hebrew one), pressing the keyboard combination Alt+Right Shift will change the keyboard group to the national (Arabic or Hebrew) one.
  2. A key sequence used to shift operations between different applications or between different functions of an application.
  3. To jump from a host session to an application on a workstation, or from the workstation to the host session.

hot link
In VisualAge RPG, a function used to copy information to and from Microsoft Windows programs.

A hashed message authentication code based one-time password algorithm. See also hashed message authentication code, one-time password.

hot plug
To install a hardware component without turning off the system.

hot servant region
A servant region that had a request dispatched to it previously and now has available threads.

Pertaining to redundant hardware (such as an adapter, a disk, a drive, or a server) that is installed and available in the event of a hardware failure.

hot spot

  1. An area of the display that, when clicked on, calls a macroinstruction.
  2. Text or a picture in a rich-text field that a user can click to perform an action, run a formula or script, or follow a link.
  3. A memory location or synchronization resource for which multiple processors compete excessively. This competition can cause a disproportionately large performance degradation when one processor blocks the resource, preventing other processors from accessing it and forcing them to become idle.
  4. A graphical device that is used in topologies to highlight the part of an end-to-end transaction that has crossed specified thresholds and has a significant transaction time deviation.

hot standby

  1. See idle standby.
  2. A redundant server that, if the primary server or hub server fails, assumes the responsibilities of the failed server.

hot start
A type of warm restart that is performed when JES terminates abnormally and an initial program load (IPL) has not yet occurred.

Pertaining to a device that is capable of being replaced while the system is on.

hot swap
To replace a hardware component without turning off the system.

hot writer
An output writer that must be started and stopped by the operator. Hot writers are typically used when operator intervention is anticipated, for example, when changing forms.

hourly average data
An average of all response times detected by a policy over a one-hour period. See also instance data.

Household Goods distance (HHG distance)
A mileage type that calculates the distance based on the routes that are authorized in the Household Goods Carriers' Bureau Committee Official Transportation Mileage Guide.

Houston Automatic Spooling Program (HASP)
A mainframe spooling program that provides task management, job management, and data management functions.

hover drill button
A button that facilitates the ability to drill down on members. Hover drill buttons can be permanently visible, or visible only when hovering with the mouse pointer over a member. It is also possible not to show hover drill buttons.

hover help
Explanatory text that can be viewed by moving a cursor over a graphical user interface (GUI) item such as an icon, field, or text string. Hover help can contain rich text and links. See also tooltip.

See high-performance computing.

See high-performance file system.

See high-performance option.

See high-performance optical file system.

See High-Performance Routing.

HPR connection
See Rapid Transport Protocol connection.

HPR pipe
See Rapid Transport Protocol connection.

HPS network
The network that interconnects the High Performance Switch (HPS) adapters.

See host print transform.

See high-performance transmission subsystem.

HP webOS (webOS)
A closed source, proprietary mobile operating system designed by Palm and currently owned by Hewlett Packard. HP webOS can operate within a Microsoft Windows environment. See also mobile operating system.

See human readable interpretation.

See hardware system area.

See high speed data entry.

See high-speed link.

HSL ring
See high-speed link ring.


  1. See hierarchical storage management.
  2. See hardware service manager.

HSM client
See hierarchical storage management client.

HSM complex (HSMplex)
One or more z/OS images running DFSMShsm that share a common set of control data sets (CDSs).

See HSM complex.

HS organization
See hierarchic sequential organization.

See High-Speed Packet Access.

See Evolved High-Speed Packet Access.

See high-speed sequential processing.

See Hyper-Threading.

See Hypertext Markup Language.

HTML form element
An element that allows the user to enter information, such as text fields, text area fields, drop-down menus, radio buttons, or checkboxes, in a form.

See Hypertext Transfer Protocol.

HTTP channel
A type of channel within a transport chain that provides client applications with persistent HTTP connections to remote hosts that are either blocked by firewalls or require an HTTP proxy server. An HTTP channel is used to exchange application data in the body of an HTTP request and an HTTP response that is sent to and received from a remote server.

See HTTP daemon.

HTTP daemon (HTTPd)
A multithreaded web server that receives incoming Hypertext Transfer Protocol (HTTP) requests.

HTTP method
An action that is used by the Hypertext Transfer Protocol. HTTP methods include GET, POST, and PUT.

See HyperText Transfer Protocol-Next Generation.

A web protocol for secure transactions that encrypts and decrypts user page requests and pages returned by the web server.

HTTP request

  1. A transaction that a web browser initiates and that adheres to HTTP.
  2. A request sent to the site either during the Explore or Test stage of the scan.

HTTP response
A response sent by the server.


  1. See HTTP over SSL.
  2. See Hypertext Transfer Protocol Secure.

HTTP server
A program that enables a computer that uses the Hypertext Transfer Protocol (HTTP) to serve objects by responding to requests from other programs, such as browsers.

HTTP Server for i5/OS
A licensed program that enables a computer that uses the Hypertext Transfer Protocol (HTTP) to serve objects by responding to requests from other programs, such as browsers. The IBM HTTP Server for i5/OS, which supports the Secure Sockets Layer (SSL) protocol, provides secure communications between a server and an SSL-capable browser.

HTTP transaction
A single HTTP request, such as clicking a link, and an associated response, such as displaying a page.


  1. The primary organization that determines a business model. For example, a multi-divisional corporation, third-party logistics (3PL), or a marketplace can all be hubs.
  2. A half-duplex device that sums all of its input and then broadcasts that sum on all output to the connected adapters. A hub has a large collision domain and shared media. See also site.
  3. An intermediate site between source sites and destination sites.
  4. A customer-facing store that enables partners or clients.
  5. A sponsor that supports that enterprise, buyer, seller, and administration roles.
  6. A point, or piece of hardware, that connects multiple devices in a network.

hub administrator
The superuser who configures the hub and who has the ability to perform all the tasks associated with setting up and administering the hub.

The gradual variations of colors such as blue, green, red, yellow, and so on.

Huffman coding
A character-coding technique to compress data.

human computing
The practice of creating computers that are more user-friendly, intuitive, and applicable to large segments of the population.

human readable interpretation (HRI)
In AFP Utilities, the characters printed above or below a bar code. These characters are read by people, not by scanners.

human task
An interaction between people and business processes or services. See also inline task, stand-alone task.

human workflow
A business process flow that includes human interactions.

hundredweight (CWT)
A unit of weight that represents 100 pounds in the United States and Canada.

hung terminal
A terminal to which a session is disrupted and cannot send or receive commands.

hunt group

  1. A group of Domino servers that are assigned one phone number. Clients dial the one phone number and connect to any available server. Hunt groups balance the load on servers.
  2. A set of telephone lines from which a non-busy line is hunted to handle, for example, an incoming call.

See hardware.

See Hardware Management Console Application.

See high watermark setup.

See hardware support.

An integrated test, trace, and monitoring environment, based on Eclipse, that provides standards, tools, and tool interoperability. Now obsolete.

hybrid analysis engine
An aggregate analysis engine where more than one of its component analysis engines are deployed in the same address space and one or more are deployed remotely. See also analysis engine.

hybrid cloud
A cloud computing environment that consists of multiple public and private resources.

hybrid code
Program statements that have not been internationalized with respect to code page, especially where data constants contain variant characters. Such statements can be found in applications written in older implementations of MVS, which required syntax statements to be written using code page IBM-1047 exclusively. Such applications cannot be converted from one code page to another using iconv().

hybrid marketing
The ability to optimally choose specific internal and external resources which best meet the customers' needs at each step in the sales cycle.

hybrid request
A request that is a combination of contingent staff requests and project requests.

hybrid route
A process through which each task in the sales cycle is analyzed from a customer requirements and channel capabilities standpoint, then designated to be performed by the channel which delivers each function at the most competitive cost.

hybrid search
A combined Boolean search and free text search.

See multidimensional array.

A link that has multiple sources and multiple sinks. A hyperedge connects multiple nodes and is used in applications such as electrical signal diagrams, multiflow visualization, network management, and UML diagrams. See also hypergraph.

A graph that contains a finite set of nodes connected by a finite set of hyperedges. See also hyperedge.

An instance of the class IlvHyperGrapher. It is a grapher that can contain three types of objects: a node, a link, and a hyperedge.

An element in an electronic document, such as a web page that links to another area in that document or a different document.

A function that provides continuous availability against storage errors, and is based on storage-based synchronous replication. If physical connectivity exists between the host and the secondary storage subsystem, HyperSwap enables the host to transparently switch the I/O operations of the applicant to the secondary volumes.

A way of presenting information online with connections (called hypertext links) between one piece of information (called a hypertext node) and another.

hypertext link

  1. The connection between one hypertext node and another.
  2. A connection between one piece of online information and another.

Hypertext Markup Language (HTML)
A markup language that conforms to the Standard Generalized Markup Language (SGML) standard and was designed primarily to support the online display of textual and graphical information, including hypertext links.

hypertext node
In a hypertext environment, a complete module of information that is linked to other relevant modules by hypertext links.

Hypertext Transfer Protocol (HTTP)
An Internet protocol that is used to transfer and display hypertext and XML documents on the web.

HyperText Transfer Protocol-Next Generation (HTTP-NG)
A replacement for HTTP 1.0, HTTP-NG maintains HTTP 1.0's simplicity while adding important features such as security and authentication.

Hypertext Transfer Protocol Secure (HTTPS)
An Internet protocol that is used by web servers and web browsers to transfer and display hypermedia documents securely across the Internet.

Hyper-Threading (HT)
A technology with which a single processor can function as two virtual processors and execute two threads simultaneously.

Software or a physical device that enables multiple instances of operating systems to run simultaneously on the same hardware.

See hertz.