A compressed file that uses a method of compression that compresses
the entire file rather than breaking it up, often used for distributing
open source code.
Numerics
5250 display
Any display device that uses the 5250 data stream.
5250 emulation
Any one of many licensed programs that allow a personal computer
to perform like a 5250 display station or printer and to use the functions
of an IBM i operating system.
The ability to read, update, or otherwise use a resource. Access
to protected resources is usually controlled by system software.
active
Pertaining to a resource that is currently operational.
adapter
A mechanism for connecting two unlike parts or machines, or for
electrically or physically connecting a device to a computer or to
another device.
advanced management module (AMM)
A hardware unit that provides system-management functions for
all the blade servers in a BladeCenter chassis.
Advanced Peer-to-Peer Networking (APPN)
An extension to SNA that features distributed network control,
dynamic definition of network resources, automated resource registration,
and automated directory lookup. This network architecture supports
the routing of data in a network between two or more Advanced Peer-to-Peer
Communication (APPC) systems that do not need to be directly connected.
Advanced Program-to-Program Communication (APPC)
An implementation of the SNA LU 6.2 protocol that allows interconnected
systems to communicate and share the processing of programs.
Advanced System Management Interface (ASMI)
A graphical interface that is part of the service processor firmware.
The ASMI manages and communicates with the service processor. The
ASMI is required to set up the service processor and to perform service
tasks, such as reading service processor error logs, reading vital
product data, and controlling the system power.
AIX
A UNIX operating system developed by IBM that is designed and
optimized to run on POWER microprocessor-based hardware such as servers,
workstations, and blades.
alphanumeric
Pertaining to a character set that contains letters, digits, and
usually other characters, such as punctuation marks.
alternate installation device
A tape device that is used to load Licensed Internal Code from
the tape device to the load-source disk unit during a restore or installation
operation. The alternate installation device can be on a different
bus unit or on a different input/output processor (IOP) than the load-source
disk unit.
alternate installation IPL
A special type of installation IPL (a D-mode IPL) in which the
system uses the installation device to IPL itself. The system then
copies the Licensed Internal Code from the alternate installation
device to the load-source disk unit.
alternate IPL
The process of loading code into main storage from a designated
input/output device instead of from the load-source disk unit for
the system, and of preparing for system operations. An alternate IPL
is a type D IPL.
alternating current (ac)
An electric current that reverses its direction at regularly recurring
intervals.
alternative sector
A sector on the disk that is reserved by the system and then made
available when a sector is damaged or defective.
American National Standards Institute (ANSI)
A private, nonprofit organization whose membership includes private
companies, U.S. government agencies, and professional, technical,
trade, labor, and consumer organizations. ANSI coordinates the development
of voluntary consensus standards in the U.S.
American Standard Code for Information Interchange (ASCII)
A standard code used for information exchange among data processing
systems, data communication systems, and associated equipment. ASCII
uses a coded character set consisting of 7-bit coded characters.
A hardware device with integrated software that is dedicated to
a specific task or set of business requirements.
application programming interface (API)
An interface that allows an application program that is written
in a high-level language to use specific data or functions of the
operating system or another program.
An entire device or feature attached to a processing unit, including
required adapters.
attended mode
An Operations Console state that requires the local console operator
to approve each remote request for control of a System i product when
the local console is in control.
attended mode IPL
A type of IPL in which the IPL stops at the dedicated service
tools (DST) environment, allowing the user to make changes to the
system or to debug a problem with the system. See also unattended mode IPL.
authority
The right to access objects, resources, or functions.
authorize
To allow a user to communicate with or make use of an object,
resource, or function.
authorized program analysis report (APAR)
A request for correction of a defect in a supported release of
a program supplied by IBM.
auxiliary storage
All addressable storage other than main storage. See also memory.
auxiliary storage pool (ASP)
One or more storage units that are defined from the storage devices
or storage device subsystems that make up auxiliary storage. An ASP
provides a way of organizing data to limit the effect of storage-device
failures and to reduce recovery time.
A group of disk units defined from the auxiliary storage devices.
See also system ASP, user ASP.
B
backplane
A hardware part that has (in one or more planes) logic paths,
low-voltage distribution paths, and grounding paths of a section of
a machine.
backup
A tape, diskette, or save file containing saved objects.
Pertaining to a system, device, file, or facility that can be
used in the event of a malfunction or loss of data.
back up
To save information or objects on a system, usually to tape or
diskette, for safekeeping.
backup console
A console that, in the event of a failure, can be used as the
system console that manages the operating system. See also system console.
basic input/output system (BIOS)
The code that controls basic hardware operations, such as interactions
with diskette drives, hard disk drives, and the keyboard.
battery power unit
A source of electrical power that can be used when the normal
utility power fails.
The amount of heat required to raise a pound of water by 1 degree
Fahrenheit.
British thermal unit per hour (Btu/hr.)
An English unit of measure for heat produced in one hour.
broadcast storm
A situation where one message that is broadcast across a network
results in multiple responses. Each response generates more responses,
causing excessive transmission of broadcast messages. Severe broadcast
storms can block all other network traffic, but they can usually be
prevented by carefully configuring a network to block illegal broadcast
messages.
The dedicated allocation of an entire bus and all accompanying
resources (input/output processors and input/output devices) to a
particular logical partition. See also IOP-level
partitioning.
A communication link established between a product and a service
provider. The product can use this link to place a call to IBM or
to another service provider when it requires service. With access
to the machine, service personnel can perform service tasks, such
as viewing error and problem logs or initiating trace and dump retrievals.
capacity on demand (CoD)
The ability of a computing system to increase or decrease its
performance capacity as needed to meet fluctuations in demand.
capped partition
A logical partition in a shared processor pool whose processor
use never exceeds its assigned processing capacity.
card
An electronic circuit board that is plugged into a slot in a system
to give it added capabilities.
Pertaining to a thermometric scale at which water boils at 100
degrees and freezes at 0 degrees in standard atmospheric pressure.
central processor complex (CPC)
A physical collection of hardware that consists of main storage,
one or more central processors, timers, and channels.
certificate authority (CA)
A trusted third-party organization or company that issues the
digital certificates. The certificate authority typically verifies
the identity of the individuals who are granted the unique certificate.
checkstop
A severe error inside a processor core that causes a processor
core to stop all processing activities.
A software program or computer that requests services from a server.
See also host, server.
client logical partition
A logical partition that uses the I/O resources of another logical
partition, for example, a logical partition that uses the resources
of a Virtual I/O Server logical partition.
cluster
A set of independent systems or logical partitions (called nodes)
that are organized into a network for the purpose of sharing resources
and communicating with each other.
cluster-ready hardware server (CRHS)
A software component that provides management subsystem communication
and methods for discovering components within a management subsystem.
cluster storage subsystem
A group of clusters where each cluster consists of one or more
logical partitions that have a shared storage pool.
Cluster Systems Management (CSM)
Systems management software that is designed to scale to large-size
clusters.
The blank line on a display where commands, option numbers, or
selections can be entered.
command-line interface (CLI)
A computer interface in which the input and output are text based.
commercial processing workload (CPW)
An application that is run on System i models and processors to
determine processor performance. The CPW workload is representative
of commercial applications, particularly those that do significant
database processing in conjunction with journaling and commitment
control.
communication adapter
A device that allows network communication.
compact disc (CD)
An optical disc that stores digital data.
compact-disc read-only memory (CD-ROM)
High-capacity read-only memory in the form of an optically read
compact disc.
concurrent
Pertaining to the shared use of resources by multiple interactive
users or application programs at the same time.
concurrent addition
The addition of hardware to a hardware unit while it is operational.
concurrent cold repair
Repair to hardware that is electrically isolated from the running
system. The hardware that is isolated has no resources that are being
used by the system when the repair is started.
concurrent hot repair
Repair to hardware that is electrically connected to the system.
The hardware being repaired might have resources that are being used
by the system when the repair is started.
concurrent maintenance
Service or maintenance that is performed on a hardware unit in
the system while the system is fully or partially operational.
concurrent repair
Repair to hardware in a hardware unit while it is operational.
conduit
A plastic or metal piping system that is used to protect and route
electrical wiring.
configuration
The manner in which the hardware and software of a system, subsystem,
or network are organized and interconnected.
To describe the interconnected arrangement of the devices, programs,
communications, and optional features installed on a system.
To describe setting up auxiliary storage pools and checksum protection.
controller
A device that coordinates and controls the operation of one or
more input/output devices (such as workstations) and synchronizes
the operation of such devices with the operation of the system as
a whole.
control panel
A panel that contains lights and switches that are used to observe
status and to operate or service the system.
The amount of processor capacity (in units of 1/100 of a physical
processor) that is assigned to a logical partition.
cursor
A movable symbol on a display, often a blinking or solid block
of light, that identifies a choice to select, indicates where user
interaction with the keyboard will appear, or indicates a position
of interest on the display surface.
A named control structure used by an application program to point
to and select a row of data from a set.
custom card identification number (CCIN)
A unique alphanumeric number that is assigned many individual
hardware parts or assemblies.
customer installable feature (CIF)
An assembly or part that a customer can replace.
customer-replaceable unit (CRU)
An assembly or part that a customer can replace.
D
data center
A centralized repository of data and information relating to a
particular field of knowledge.
data migration
The movement of data when the software is upgraded or the data
is transferred to a different hardware server or model.
A unit of signal strength or loudness, such as the signal on a
data communications channel.
dedicated service tools (DST)
Service functions that are available only from the console and
that can run when the operating system is not available, as well as
when the operating system is available.
defragmentation
The process of running a software utility to rewrite fragmented
data to contiguous sectors of a computer storage medium to improve
access and retrieval time.
device
A piece of equipment such as a workstation, printer, disk drive,
tape unit, or remote system.
device configuration
The physical placement of display stations, printers, and so forth;
and the configuration descriptions that describe the physical configuration
to the system and describe how the configuration will be used by the
system.
device driver (DD)
A program that provides an interface between a specific device
and the application program that uses the device.
Pertaining to data in the form of digits. See also analog.
digital versatile disc (DVD)
An optical disc that has the same overall dimensions of a CD-ROM,
but has significantly higher capacities than a CD-ROM. DVDs are also
double sided, whereas CD-ROMs are single sided.
The mechanism used to read and write information on a disk.
diskette
A thin, flexible magnetic plate that is permanently sealed in
a protective cover. It can be used to store information copies from
the disk or another diskette.
disk unit enclosure
A physical enclosure containing one or more disk units.
display station
A device, usually equipped with a keyboard and a display device,
capable of sending and receiving information over a communications
line. See also workstation.
D-link
The optical connections between supernodes for forming an HPC
cluster.
In Internet communications, a name of a host system. A domain
name consists of a sequence of subnames that are separated by a delimiter
character, for example, www.ibm.com.
A small circuit board with memory-integrated circuits containing
signal and power pins on both sides of the board. See also single inline memory module.
A communications protocol that is used to centrally manage configuration
information. For example, DHCP automatically assigns IP addresses
to computers in a network.
dynamic IP address
A temporary IP address for a transient device or logical unit
on a network: for example, a personal computer. See also IP address.
dynamic LPAR (DLPAR)
The ability to move processors, memory, and interactive performance
between logical partitions without restarting a logical partition
or the server. See also logical partition, managed system.
A unit of measure, established by the Electronic Industries Association,
equal to 44.45 millimeters (1.75 inches).
electronic customer support (ECS)
A part of the operating system that allows a customer to access
the question-and-answer (Q & A) function; problem analysis, reporting,
and management; IBM product information; and technical information
exchange.
Electronic Industries Alliance (EIA)
An organization of electronics manufacturers that advances the
technological growth of the industry, represents the views of its
members, and develops industry standards.
A function that provides automatic hardware problem-reporting
to help predict and prevent hardware errors by early detection of
potential problems. With this function, users can also download fixes
and automatically submit problems to IBM when appropriate.
electrostatic discharge (ESD)
The flow of current that results when objects having a static
charge come into close enough proximity to discharge.
emulation
The use of software, hardware, or both by one system to imitate
another system. The imitating system accepts the same data, runs the
same programs, and achieves the same results as the imitated system.
enclosure services manager (ESM)
A redundant and hot-swappable SAS communication FRU that provides
SAS expander and SES functions.
Enhanced 5250 Emulation
A program that allows a personal computer and a printer to be
attached to a System i product and perform the functions of one or
two 5250 workstations on one twinaxial cable. The workstations can
be one display station, two display stations, or one display station
and one printer.
entitled memory
The maximum amount of physical memory that is guaranteed to be
available for I/O mapping by a logical partition at any given time.
ephemeral port
A temporary port assigned by a server's IP stack from a designated
range of ports.
A packet-based networking technology for local area networks (LANs)
that supports multiple access and handles contention by using Carrier
Sense Multiple Access with Collision Detection (CSMA/CD) as the access
method. Ethernet is standardized in the IEEE 802.3 specification.
See also local area network.
expansion unit
A machine type or feature that can be connected to a system unit
to provide additional storage and processing capacity. This expansion
unit may contain I/O hardware such as cards, tapes, and disk drives.
F
fabric
A complex network of hubs, switches, adapter endpoints, and connecting
cables that support a communication protocol between devices. For
example, Fibre Channel uses a fabric to connect devices.
fabric manager
Software that initializes and monitors communications network
components.
facsimile machine (fax machine)
A functional unit that converts images to signals for transmission
over a telephone system or that converts received signals back to
images.
failover
An automatic operation that switches to a redundant or standby
system or node in the event of a software, hardware, or network interruption.
Fast Ethernet
An Ethernet standard that provides a data rate of 100 Mbps.
fax
To transmit an image, using a telephone system and facsimile machines.
The printed copy received from a facsimile machine.
Part of a product that is either included with the product or
can be ordered separately.
feature code
A code used by IBM to process hardware and software orders.
fiber optic
Describing a transmission medium composed of a glass fiber light
path surrounded by a cladding material that confines the signal to
the light path.
fiber optic cable
A fiber or bundle of fibers in a structure built to meet optic,
mechanical, and environmental specifications.
Fibre Channel (FC)
A technology for transmitting data between computer devices. It
is especially suited for attaching computer servers to shared storage
devices and for interconnecting storage controllers and drives.
field-replaceable unit (FRU)
An assembly that is replaced in its entirety when any one of its
components fails.
file
A collection of related data that is stored and retrieved by an
assigned name.
firewall
A network configuration, typically both hardware and software,
that prevents unauthorized traffic into and out of a secure network.
flash memory
A computer chip with a read-only memory that retains its data
when the power is turned off and that can be electronically erased
and reprogrammed without being removed from the circuit board.
flexible service processor (FSP)
Firmware that provides diagnostics, initialization, configuration,
runtime error detection, and correction. The flexible service processor
connects the managed system to the Hardware Management Console.
footprint
The amount of computer storage that is occupied by a computer
program. For example, if a program occupies a large amount of storage,
it has a large footprint.
free space
The total amount of unused space in a page, data set, file, storage
medium, or file system. Free space is the space that is not used to
store records, control information, or files.
A licensed processor core other than a Power IFL processor core.
The AIX, IBM i, VIOS, and Linux partitions can be run on a general-purpose
processor core.
genucode
A program to download microcode to a specific adapter or device.
This program is provided with a microcode update.
graphical user interface (GUI)
A computer interface that presents a visual metaphor of a real-world
scene, often of a desktop, by combining high-resolution graphics,
pointing devices, menu bars and other menus, overlapping windows,
icons and the object-action relationship.
A nonremovable storage medium used for storage of data on a personal
computer.
hard disk drive (HDD)
A stand-alone disk drive that reads and writes data on rigid disks
and can be attached to a port on the system unit.
Hardware Management Console (HMC)
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 managed system.
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.
Pertaining to a numbering system that has a base of 16.
high availability (HA)
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.
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.
high-performance computing (HPC)
A technology that requires massive computational powers, such
as supercomputers or computer clusters, to solve complex problems.
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.
An emulation session to a logical partition's operating system.
host
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.
The controlling or highest-level system in a data communications
configuration.
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 channel adapter (HCA)
Based on InfiniBand technology, a port connection on a system
allowing a network fabric interconnect.
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 name
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 IP address.
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.
hot-spare
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-swap
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.
A point, or piece of hardware, that connects multiple devices
in a network.
I
i5/OS
The IBM licensed program that was used as the operating system
for System i servers. The predecessor to i5/OS was Operating System/400
(OS/400). See also IBM i, Operating System/400, System i.
The IBM licensed program that is the integrated operating system
for Power Systems servers. It integrates such functions as relational
database, security, web services, networking, and storage management
capabilities. The predecessor to IBM i was i5/OS, which was preceded
by Operating System/400 (OS/400). See also i5/OS, Operating System/400, System i.
icon
A graphical representation of an object (for example, a file or
program) that consists of an image, an image background, and a label.
initial program load (IPL)
The process that loads the system programs from the system auxiliary
storage, checks the system hardware, and prepares the system for user
operations.
input/output adapter (I/O adapter, IOA)
A functional unit or a part of an I/O controller that connects
devices to an I/O processor.
input/output data
Data provided to the computer or data resulting from computer
processing.
input/output processor (I/O processor, IOP)
A processor dedicated to controlling channels or communication
links.
integrated battery feature (IBF)
Battery backup hardware that protects against power line disturbances
such as short-term power loss or brown-out conditions.
A browser-based management interface that is used to manage a
System p or blade server. The IVM can be used to create logical partitions,
manage virtual resources such as storage, and view service information
related to the server.
Integrated xSeries Adapter (IXA)
A PCI expansion card that can be installed in selected System
x models and that provides a high-speed link to a System i product.
Internet
The worldwide collection of interconnected networks that use the
Internet suite of protocols and permit public access.
Internet Protocol (IP)
A protocol that routes data through a network or interconnected
networks. This protocol acts as an intermediary between the higher
protocol layers and the physical network. See also Transmission Control Protocol.
interrupt
An identification that is used to send a signal to the processor
indicating that the installed hardware requires attention.
A signal sent by an I/O device to the processor when an error
has occurred or when assistance is needed to complete I/O. An interrupt
usually suspends the running of the program that is currently running.
intranet
An organization's internal network that uses the IP protocol.
intrarack
Pertaining to interfaces or links within a rack of servers or
switches.
A device that provides the interface between the processors and
memory in the central electronics complex and the I/O drawers that
are connected to it.
A dedicated allocation of the input/output processor (IOP) and
all accompanying resources (input/output devices) to a particular
logical partition. IOPs on a single bus may be dedicated to different
logical partitions. The bus resources that contain these IOPs must
be shared. See also bus-level partitioning.
Written information used by service representatives to repair
IBM equipment. An isolation procedure contains yes/no questions and
procedures that direct the user to the failing part of the equipment.
A small piece of plastic-covered metal that is used to connect
two contacts and complete a circuit.
K
kernel
In OSI, a session-layer functional unit that supports the basic
session services required to establish connections, transfer normal
data, and release connections.
kernel-based virtual machine (KVM)
An open source virtualization software for Linux that is based
on hardware virtualization extensions (Intel VT-X and AMD-V) and a
modified version of QEMU.
key
A cryptographic mathematical value that is used to digitally sign,
verify, encrypt, or decrypt a message. See also private key, public key.
key ring
In computer security, a file that contains public keys, private
keys, trusted roots, and certificates.
key ring file
A binary file that is protected by a password and stores one or
more certificates on the server hard drives. There are two types of
key ring files: server and CA.
keystore
In security, a file or a hardware cryptographic card where identities
and private keys are stored, for authentication and encryption purposes.
Some keystores also contain trusted or public keys. See also truststore.
keystore file
A key ring that contains both public keys that are stored as signer
certificates and private keys that are stored in personal certificates.
keytab file
A file on the service's host system that contains entries each
of which contains the service principal's name and encrypted secret
key.
A switch field replaceable unit (FRU) that plugs into a switch
chassis. It contains connectors for interconnecting with adapters
and other switches. Internal to the switch chassis, a leaf connects
to spine modules, which provide connectivity to other leaf FRUs in
the same switch chassis by way of a midplane.
leaf card
A card internal to a switch chassis that provides external connectivity
by using cable connectors, and that provides internal communication
to spines as a path to other leaf cards.
leaf module
A leaf card in a switch chassis that contains a specific number
of InfiniBand port connectors and has the capability of communicating
with other leaf modules through connections to spines.
leaf switch chip
A chip that provides communication paths and switching between
the paths and that populates a leaf card.
A legal agreement that authorizes the use of proprietary information
including, but not limited to, copyrighted or patented information.
Licensed Internal Code
The layered architecture below the machine interface (MI). The
Licensed Internal Code is a proprietary system design that carries
out many functions. These functions include but are not limited to
storage management, pointers and addressing, program management functions,
exception and event management, data functions, I/O managers, and
security.
Licensed Internal Code fix
A temporary solution to, or bypass of, a defect in a current release
of the Licensed Internal Code.
licensed program (LP)
A separately priced program and its associated materials that
have a copyright and are offered to customers under the terms and
conditions of a licensing agreement.
light-emitting diode (LED)
A semiconductor chip that gives off visible or infrared light
when activated.
Lightweight Directory Access Protocol (LDAP)
An open protocol that uses TCP/IP to provide access to directories
that support an X.500 model and that does not incur the resource requirements
of the more complex X.500 Directory Access Protocol (DAP). For example,
LDAP can be used to locate people, organizations, and other resources
in an Internet or intranet directory.
limited paging
A phase of the IPL sequence that takes place prior to full paging
during which only the data on the load-source disk unit can be accessed
by the normal Licensed Internal Code functions. See also full paging, prestatic paging, static paging.
line description
An object that contains information describing a particular communications
line that is attached to the system. The system-recognized identifier
for the object type is *LIND.
link aggregation
The grouping of physical network interface cards, such as cables
or ports, into a single logical network interface. Link aggregation
is used to increase bandwidth and network availability.
Live Partition Mobility (LPM)
A component of the PowerVM Enterprise Edition hardware feature
that provides the ability to move AIX, IBM i, and Linux logical partitions
from one system to another. The mobility process transfers the system
environment, which includes the processor state, memory, attached
virtual devices, and connected users.
L-link
The connections between the hub switch chips that are located
within a supernode.
load-source disk unit
The disk unit that contains the Licensed Internal Code for the
system. This unit is always identified as unit number 1 in the disk
configuration displays.
local area network (LAN)
A network that connects several devices in a limited area (such
as a single building or campus) and that can be connected to a larger
network. See also Ethernet.
logical memory
The address space, assigned to a logical partition, that the operating
system perceives as its main storage. For a shared memory partition,
a subset of the logical memory is backed up by physical main storage,
and the contents of the remaining logical memory are kept in secondary
storage.
logical partition (LP, LPAR)
One or more virtualized images of a hardware computing system
that can include shared and dedicated resources assigned from the
pool of resources available on a physical server. Each image appears
to the operating system running within it to be a unique instance
of a physical server. See also dynamic
LPAR, virtual server, virtualization.
logical partition firmware
The code that is loaded into an AIX or Linux logical partition
from the server firmware.
logical partitioning
A function of an operating system that creates segments of resources
that can be run on copies, or instances, of the operating system and
associated applications.
logical unit number (LUN)
In the Small Computer System Interface (SCSI) standard, a unique
identifier used to differentiate devices, each of which is a logical
unit (LU).
A process of collecting data from the system's main storage. It
can be done automatically by the service processor as a result of
a system failure, or it can be performed manually by the operator
when there appears to be a system failure.
maintenance analysis procedure (MAP)
In hardware maintenance, a step-by-step procedure that assists
an IBM service representative to trace a symptom to the cause of the
failure.
Magnetic disks, magnetic tapes, compact discs (CDs), and digital
video disks (DVDs).
Media Access Control (MAC)
In networking, the lower of two sublayers of the Open Systems
Interconnection model data link layer. The MAC sublayer handles access
to shared media, such as whether token passing or contention will
be used.
megabyte (MB)
For processor storage, real and virtual storage, and channel volume,
2 to the 20th power or 1,048,576 bytes. For disk storage capacity
and communications volume, 1,000,000 bytes.
memory
Program-addressable storage from which instructions and other
data can be loaded directly into registers for subsequent running
or processing. See also auxiliary storage.
memory affinity
A feature available in AIX to allocate memory attached to the
same multiple chip module (MCM) on which the process runs. Memory
affinity improves the performance of applications on some IBM Power
Systems servers.
memory weight
A relative value that is one of the factors in determining the
allocation of physical memory to the shared memory partitions. A higher
value relative to the values set for other shared memory partitions
increases the probability of the hypervisor allocating more physical
memory to the shared memory partition.
menu
A displayed list of items from which a user can make a selection.
A logical partition that uses a partial processor. With Micro-Partitioning
technology, a partition can be as small as 1/10th of a processor or
can consist of full plus partial processors.
middleware
Software that acts as an intermediate layer between applications
or between client and server. It is used most often to support complex,
distributed applications in heterogeneous environments.
migrate
To install a new version or release of a program to replace an
earlier version or release.
To move data from one location to another.
miscellaneous equipment specification (MES)
A hardware change that is made after the time of the initial order.
mobile partition
A logical partition that can be moved from the source server to
the destination server.
modular water unit (MWU)
A unit that circulates water, chilled by the heat exchanger, and
distributes it to the nodes.
A system processor that as a unit contains more than one processor
function such as a diskette controller, a storage device controller,
and a communications controller.
multiple chip module (MCM)
The fundamental processor building block of some IBM Power Systems
servers.
A set of links to other web pages in a website. For example, a
navigation bar is typically located across the top or down the side
of a page and contains direct links to the major sections within the
website.
navigation tree
A hierarchical structure that is used to access information.
n-core
Any valid configuration of processors for a system that is capable
of supporting 1 - n processors.
network
A system of resources, such as appliances, computers, and storage
devices, that are connected virtually or physically.
network address translation (NAT)
The conversion of a network address that is assigned to a logical
unit in one network into an address in an adjacent network. See also static network address translation.
In a firewall, the conversion of secure Internet Protocol (IP)
addresses to external registered addresses. This enables communications
with external networks but masks the IP addresses that are used inside
the firewall.
network administrator
A person who defines the network configuration and other network-related
information. This person controls how an enterprise or system uses
its network resources.
network boot
The process of starting a computer directly over the network rather
than from a disk.
Network Installation Management (NIM)
An environment that provides installation and configuration of
software within a network interface.
network interface controller (NIC)
Hardware that provides the interface control between system main
storage and external high-speed link (HSL) ports.
network server description (NWSD)
An object that contains a description of the characteristics of
a file server I/O processor that is attached to the system.
Network Time Protocol (NTP)
A protocol that synchronizes the clocks of computers in a network.
In communications, an end point of a communication link or a junction
common to two or more links in a network. Nodes can be processors,
communication controllers, cluster controllers, terminals, or workstations.
Nodes can vary in routing and other functional capabilities.
A grouping of processor, memory, and I/O hub hardware resources
in the system. On systems of machine type FHA, a node is a processor
book. On systems of machine type MMA, a node is a drawer.
In networking, a point capable of sending and receiving data.
A node can be a device, such as printer or workstation, a system,
or a storage location on a disk. See also port.
nonconcurrent repair
Repair to hardware in a hardware unit when the power is off.
nonprogrammable workstation (NWS)
A workstation that does not have processing capability and does
not allow the user to change its functions.
A type of interactive application in which requests that are submitted
by users are processed as soon as they are received. Results are returned
to the requester in a relatively short period of time.
operating system (OS)
A collection of system programs that control the overall operation
of a computer system.
Operating System/400 (OS/400)
The IBM licensed program that was used as the operating system
for iSeries servers. See also i5/OS, IBM i.
Operations Console
A feature of System i Access for Windows that provides the ability
for a System i console to be either a local or a remote personal computer.
With Operations Console, a system administrator, for example, can
access the console from home.
Either a CD-ROM drive, a digital video disc (DVD), or both.
OptiConnect
A System i system area network (SAN) that allows high-speed links
between systems in a System i cluster. OptiConnect provides three
hardware technologies (SPD OptiConnect, high-speed link (HSL) OptiConnect,
and virtual OptiConnect) that can exist simultaneously on a single
cluster node.
A feature of the IBM i operating system that allows a user to
connect multiple System i systems by using SPD bus, high-speed link
(HSL) loop, or virtual interpartition technologies.
original equipment manufacturer (OEM)
A manufacturer of equipment that can be marketed by another manufacturer.
A nonvolatile entry that indicates whether the RAID parity is
out of synchronization with its associated data, for example, while
performing a write operation to the RAID array.
partition
A logical division of storage on a fixed disk. See also virtualization.
password
In computer and network security, a specific string of characters
used by a program, computer operator, or user to access the system
and the information stored within it.
A device that connects one or more subordinate PCI buses to a
primary PCI bus. The PCI bus that is closest to the system processor
is the primary PCI bus, and the subordinate buses are secondary PCI
buses.
A local serial interface that provides a high-speed data path
between the processor and attached devices. Unlike previous PCI implementations
that used a parallel bus architecture, PCI Express uses point-to-point
serial links called lanes. See also Peripheral
Component Interconnect.
PCI host bridge (PHB)
A device that merges data from PCI bridges for delivery to the
system processor.
An enhancement to the Peripheral Component Interconnect (PCI)
architecture. PCI-X enhances the Peripheral Component Interconnect
(PCI) standard by doubling the throughput capability and providing
additional adapter-performance options while maintaining backward
compatibility with PCI adapters. See also Peripheral
Component Interconnect.
An I/O device that is assigned to a logical partition and that
is used directly.
pinned memory
A page in memory that is always available for the applications
that are in physical memory.
planar
A hardware part that has (in one or more planes) logic paths,
low-voltage distribution paths, or grounding paths of a section of
a machine.
platform
The combination of an operating system and hardware that makes
up the operating environment in which a program runs.
Point-to-Point Protocol (PPP)
A data-link protocol for communication between two computers that
use a serial interface, typically a personal computer connected by
telephone line to a server.
port
A hardware interface to which an I/O device is attached for the
purpose of sending and receiving data.
Portable Document Format (PDF)
A standard specified by Adobe Systems, Incorporated, for the electronic
distribution of documents. PDF files are compact; can be distributed
globally via email, the web, intranets, or CD-ROM; and can be viewed
with the Acrobat Reader.
A licensed processor core that is enabled by feature code ELJ1
on IBM Power Systems servers. Each Power IFL processor core feature
enables one processor core. Only the Linux operating system can be
run on Power IFL processor cores.
Power Integrated Facility for Linux (Power IFL)
An optional lower cost per processor core activation for Linux-only
workloads on IBM Power Systems servers.
power-on light
The light on the operator panel that indicates that the DC power
in the system is functioning.
power-on self-test (POST)
A series of internal diagnostic tests activated each time the
system power is turned on.
PowerVM Active Memory Sharing
A technology that enables logical partitions to share the memory
in the shared memory pool.
A system that is shipped with the licensed programs and program
temporary fixes (PTFs) already installed on the disk.
prestatic paging
A phase of the IPL sequence that takes place prior to static paging,
where normal Licensed Internal Code functions cannot access data from
any disk (neither load-source nor non-load-source disk units). See
also full paging, limited paging, static paging.
private key
In secure communication, an algorithmic pattern used to encrypt
messages that only the corresponding public key can decrypt. The private
key is also used to decrypt messages that were encrypted by the corresponding
public key. The private key is kept on the user system and is protected
by a password. See also key, public key.
private network
A network established and operated by a private organization or
corporation for users within that organization or corporation. See
also public network, public network.
problem analysis
The process of finding the cause of a problem. For example, a
program error, device error, or user error.
processor
A device for processing data from programmed instructions. It
may be part of another unit.
processor core
A single processing unit on a chip with multiple processing units.
product activity log (PAL)
A log of system data, Licensed Internal Code data, software components,
subsystem information, and I/O device data.
programmable workstation
A workstation that has some degree of processing capability and
allows the user to change its functions.
program temporary fix (PTF)
For System i, System p, and System z products, a package containing
individual or multiple fixes that is made available to all licensed
customers. A PTF resolves defects and might provide enhancements.
prompt
A message or a displayed symbol that requests information or user
action. The user must respond to allow the program to proceed.
In secure communication, an algorithmic pattern used to decrypt
messages that were encrypted by the corresponding private key. A public
key is also used to encrypt messages that can be decrypted only by
the corresponding private key. Users broadcast their public keys to
everyone with whom they must exchange encrypted messages. See also key, private
key.
public network
Generically, a network operated by common carriers or telecommunications
administrators for the provision of circuit-switched, packet-switched,
and nonswitched lines to the public. See also private network.
Q
QEMU
An open source emulator for complete PC systems. In addition to
emulating a processor, QEMU permits emulation of all necessary subsystems,
such as networking and video hardware, as well as advanced concepts.
quiesce
To end a process or shut down a system after allowing normal completion
of active operations.
R
rack
A free-standing structure or frame that can hold multiple servers
and expansion units.
rack stabilizer
A plate that holds the rack stable or steady when a device is
pulled out for service.
A form of parity RAID in which the disks operate independently,
the data stripe size is no smaller than the exported block size, and
parity check data is distributed across the array's disks.
RAID 6
A form of RAID that can continue to process read and write requests
to all of an array's virtual disks in the presence of two concurrent
disk failures.
rail
Hardware attached inside a rack to hold devices that are designated
as installable in a rack.
raw device
In UNIX-based operating systems, a block device that handles data
as a stream of bytes, rather than as a block.
A hollowed electrical fitting that contains the live parts of
a circuit.
Redundant Array of Independent Disks (RAID)
A collection of two or more physical disk drives that present
to the host an image of one or more logical disk drives. In the event
of a physical device failure, the data can be read or regenerated
from the other disk drives in the array due to data redundancy.
reference code
A group of characters that identifies the machine status or a
specific error condition.
release
A distribution of a new product or new function and authorized
program analysis report (APAR) fixes for an existing product. The
first version of a product is announced as release 1 modification
level 0.
remote
Pertaining to a system, program, or device that is accessed through
a communication line.
remote control panel
A graphical interface that is provided by Operations Console that
allows control panel operations to be performed from a remote location.
This interface allows personal computer access to the control panel
that controls operating or servicing the system.
remote input/output (RIO)
A type of hardware architecture that facilitates faster input/output
connection speeds between a system and expansion units. See also high-speed link.
remote restart
The function that restarts a logical partition on a different
physical server during a server outage.
removable media
Volumes that can be removed from the hardware devices (such as
tape cartridges and optical disks) where they are read and written.
Resource Monitoring and Control (RMC)
A subsystem that runs on each cluster node and provides global
access to subsystems and resources throughout the cluster, thus providing
a single monitoring and management infrastructure.
A network protocol for secure data exchange between two networked
devices. The client can use public-key and private-key authentication,
or password authentication, to access the remote server.
serial-attached SCSI (SAS)
A data-transfer technology that moves data to and from computer
storage devices. Serial-attached SCSI uses a point-to-point serial
protocol, which replaces the traditional, parallel SCSI bus technology.
server
A software program or a computer that provides services to other
software programs or other computers. See also client, host.
server firmware
The code that resides in system flash memory, and includes a number
of subcomponents, including POWER Hypervisor, power control, service
processor, and logical partition firmware that is loaded into either
AIX or Linux logical partitions.
server-side include (SSI)
A facility for including dynamic information in documents sent
to clients, such as current date, the last modification date of a
file, and the size or last modification of other files.
service action log
A utility that displays entries requiring action by a service
representative.
service authority
A special authority that allows the user to perform the alter
function in the service functions.
Service Focal Point
An application on the Hardware Management Console (HMC) that collects
problems from the system and from logical partitions. It is used to
view problems and to take action on problems.
service processor
The logic that contains the processor function to start the system
processor and handle error conditions.
The interface to the Hardware Management Console (HMC) that provides
hardware control and logical partition (LPAR) support for IBM Power
Systems servers.
service provider (SP)
Any company that provides services for a fee to its customers,
such as telecommunication companies, application service providers,
enterprise IT, and Internet service providers.
service request number (SRN)
A code that is used by service technicians or the customer to
determine the failing area of the system.
service tools device ID
A programming object used by both the PC and the IBM System i
model as a means to authenticate the network connection between the
two. A service tools device ID is unique to that PC and server connection.
The service tools device ID can be managed by authorized users in
dedicated service tools (DST) or system service tools (SST). The default
service tools device ID is QCONSOLE.
Physical memory that is assigned to a shared memory pool and shared
among multiple logical partitions.
shared memory pool
A defined collection of physical memory blocks that are managed
as a single memory pool by the hypervisor.
shared processor pool
A group of physical processors that provide processing capacity
that can be shared among multiple logical partitions. Processing capacity
from the shared processor pool can be assigned to each of the logical
partitions in partial processor increments. The sum of the assigned
processing capacity across all logical partitions in the shared processor
pool cannot exceed the total processing capacity of the shared processor
pool.
shared storage pool
A storage pool that provides distributed storage access to one
or more logical partitions or virtual servers in a cluster or that
can be shared by more than one subsystem.
short host name
The system or machine name portion of a fully qualified host name;
for example, in the fully qualified host name "system1.mysite.mycompany.com,"
the short host name is "system1."
In computer hardware, a small circuit card that carries a number
of surface-mounted memory chips in a space-saving configuration with
the connector pins protruding in a single line from the edge of the
card. Varying numbers of SIMMs can be plugged easily into slots in
a memory board to expand random access memory. See also dual inline memory module.
skew
The time difference between two clocks or clock values.
Small Computer System Interface (SCSI)
An ANSI-standard electronic interface that allows personal computers
to communicate with peripheral hardware, such as disk drives, tape
drives, CD-ROM drives, printers, and scanners faster and more flexibly
than previous interfaces.
A one-to-one mapping of IP addresses that allows a user to map
an IP address on an internal network to an IP address that is to be
made public. If static NAT is used, traffic can be initiated from
either side of the connection. See also network
address translation.
static paging
A phase of the IPL sequence that takes place prior to limited
paging during which only predefined areas of the load-source disk
unit can be accessed. See also full
paging, limited paging, prestatic paging.
subnet mask
For internet subnetworking, a 32-bit mask used to identify the
subnetwork address bits in the host portion of an IP address.
supernode
A group of four Power 775 CEC drawers that have a total of 1024
processor cores in addition to the memory, hub switch chips, and PCIe
slots.
A system in which functionally identical multiple processors are
used in parallel, providing simple and efficient load balancing.
Synchronous Data Link Control (SDLC)
A protocol for managing synchronous information transfer over
a data link connection.
system
A computer and its associated devices and programs.
system ASP
The auxiliary storage pool where system programs and system data
reside. It can also include user programs and user data. The system
ASP (ASP1) always exists. See also auxiliary
storage pool, user ASP.
system console
The device that is in control of the operating system after the
system has been shut down and when the system is in a restricted state.
Only one device can be the system console at one time. See also backup console.
System i
A family of IBM systems distinguished by their object-oriented
architecture, integrated relational database, and high-level machine
interface. System i systems support the IBM i, i5/OS, Operating System/400,
AIX, and Linux operating systems. See also i5/OS, IBM i.
System i Navigator
A no-charge feature of IBM System i Access for Windows that is
bundled with the IBM i operating system. System i Navigator provides
a graphical user interface to common System i management functions.
Some of the common management functions include basic operations,
TCP/IP configuration, job management, users and groups, database management,
and Management Central.
system management services (SMS)
An interface that provides information about a system or logical
partition and that performs tasks such as changing the boot list and
setting the network parameters. This interface is used for AIX or
Linux logical partitions.
System Manager Security
An application on the Hardware Management Console (HMC) that ensures
that the HMC can operate securely in the client/server mode.
system port
A serial port that is available for specifically supported functions.
This port is limited to serial-connected TTY console functions and
use of approved call-home modems, and, in some cases, an uninterruptible
power supply.
system power control network (SPCN)
An asynchronous serial communications network. SPCN connects the
power system in participating components to the operating system and
can report critical changes and power failures in those components
to the operating system. SPCN gives the operating system control of
electrical power.
system processor
The logic that contains the processor function to translate and
process the operating system commands and application program commands.
system reference code (SRC)
An alphanumeric string of characters (code) that contains information,
such as a failing field-replaceable unit, for a service representative,
customer engineer, or customer to use for servicing a system.
system service tools (SST)
The part of the service function used to service the system while
the operating system is running.
Systems Network Architecture (SNA)
The description of the logical structure, formats, protocols,
and operational sequences for transmitting information through and
controlling the configuration and operation of networks.
system unit
The part of a computer that contains the processing unit, and
may contain devices such as disk units and tape units.
T
target server
In upgrades, the planned hardware configuration and software level
that exists when the upgrade is completed.
A database that contains replication target tables.
In TCP/IP, a protocol that provides remote-terminal connection
service. Telnet enables users of one host to log on to a remote host
and interact as if they were directly attached terminal users of that
host.
terminal type (tty)
A generic device driver for a text display. A tty typically performs
input and output on a character-by-character basis.
Thin Console
An appliance that provides a 5250-based operating system console
for the IBM i operating system. This appliance connects directly to
the server using one of the HMC Ethernet ports (labeled HMC 1 and
HMC 2) on the back of the server.
thin provisioning
The ability to define a storage unit (full system, storage pool,
volume) with a logical capacity size that is larger than the physical
capacity assigned to that storage unit.
topic
A single web page at any level within an information center hierarchy.
topic collection
A functional group of web pages. A topic collection can be a grouping
at any level within an information center hierarchy.
topology
The physical or logical mapping of the location of networking
components or nodes within a network. Common network topologies include
bus, ring, star, and tree.
Transmission Control Protocol (TCP)
A communication protocol used in the Internet and in any network
that follows the Internet Engineering Task Force (IETF) standards
for internetwork protocol. TCP provides a reliable host-to-host protocol
in packet-switched communication networks and in interconnected systems
of such networks. See also Internet
Protocol.
Transmission Control Protocol/Internet Protocol (TCP/IP)
An industry-standard, nonproprietary set of communication protocols
that provides reliable end-to-end connections between applications
over interconnected networks of different types.
truststore
A key database that holds signer certificates for only the target
servers that the user trusts.
An IPL mode that automatically loads the operating system without
any user interaction. See also attended
mode IPL.
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.
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.
unit
The defined space within disk units that is addressed by the system.
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.
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.
The name used to associate the user profile with a user when a
user signs on to a system.
V
vary off
To make a device, control unit, or line unavailable for its normal
intended use.
vary on
To make an independent disk pool available for its normal, intended
use. All of the primary and secondary disk pools in a disk pool group
will vary on together.
A partition running the Virtual I/O Server (VIOS) software that
facilitates the sharing of physical I/O resources between client logical
partitions within a server.
Virtual Ethernet Port Aggregator (VEPA)
The capability of a physical server to collaborate with an adjacent
bridge to provide frame relay services between multiple virtual machines,
which are located on a server and also on the external network.
virtual Fibre Channel adapter
A virtual adapter that provides client logical partitions with
a Fibre Channel connection to a storage area network through the Virtual
I/O Server logical partition. The framework uses N_Port ID Virtualization
(NPIV) and each virtual Fibre Channel adapter has a pair of unique
Worldwide Port Names (WWPNs) associated with it.
Virtual I/O Server (VIOS)
Software that facilitates the sharing of physical I/O resources
between client logical partitions within the server.
virtualization
The substitution of virtual resources for actual resources, where
the virtual resources have the same functions and external interfaces
as their counterparts, but differ in attributes, such as size, performance,
and cost. Virtualization is commonly applied to physical hardware
resources by combining multiple physical resources into shared pools
from which users receive virtual resources.
virtual local area network (VLAN)
A logical association of switch ports based upon a set of rules
or criteria, such as Medium Access Control (MAC) addresses, protocols,
network address, or multicast address. This concept permits the LAN
to be segmented again without requiring physical rearrangement.
virtual private network (VPN)
An extension of a company intranet over the existing framework
of either a public or private network. A VPN ensures that the data
that is sent between the two endpoints of its connection remains secure.
virtual processor
A setting that defines the assigned processing capacity represented
to the operating system. Virtual processors represent a processing
capacity less than that of a physical processor. A logical partition
in the shared processor pool must have at least as many virtual processors
as its assigned processing capacity.
virtual SCSI client adapter
A virtual adapter in one logical partition that communicates with
a virtual SCSI server adapter in another partition. A virtual SCSI
client adapter allows a logical partition to access a storage device
being made available by another logical partition. See also virtual SCSI server adapter.
virtual SCSI server adapter
An adapter in one logical partition that is available to a virtual
SCSI client adapter in another logical partition. A logical partition
to which a storage device is assigned can map that device to a virtual
SCSI server adapter. See also virtual
SCSI client adapter.
virtual server
A system composed of partitioned, shared, or virtualized resources
presented from a host system. An operating system and other software
can be installed on a virtual server. See also logical partition.
virtual server network (VSN)
The capability that provides enhanced access, security control,
and integrated management for interconnected storage and virtual servers,
and for interconnected fabrics, such as virtual switches and routers.
virtual service processor (VSP)
The firmware that controls the powering on and powering off of
a logical partition, including loading the firmware that controls
the I/O slots and initializing the memory space of the logical partition.
virtual terminal
A system object, created and controlled by an application program,
that provides a functional representation or simulation of a physical
display station.
Virtual Trusted Platform Module (VTPM)
A software implementation of the Trusted Platform Module specification
that is described by the Trusted Computing Group. The Trusted Platform
Module is implemented as a physical chip on systems.
vital product data (VDP, VPD)
Information that uniquely defines system, hardware, software,
and microcode elements of a processing system.
The process of adding a VLAN number to the Ethernet packet to
logically segment a physical network, thereby restricting the network
layer 2 connectivity to the members who belong to the same VLAN.
VMware
A commercially available, proprietary virtualization environment
for System x and similar platforms.
voltage regulator module (VRM)
A replaceable module on a system board that regulates voltage
to the microprocessor.
A related collection of files available on the web that is managed
by a single entity (an organization or an individual) and contains
information in hypertext for its users. A website often includes hypertext
links to other websites.
wizard
User assistance that is an alternate path usually through complex
and infrequently performed tasks. Presented sequentially, the panels
of the wizard prompt the user for responses, and then take that data
and perform the task. Wizards complete a single task and are usually
self-contained.
workstation
A terminal or personal computer at which a user can run applications
and that is usually connected to a mainframe or a network. See also display station.
worldwide node name (WWNN)
A unique 64-bit identifier for a host containing a Fibre Channel
port. See also worldwide port name.
worldwide port name (WWPN)
A unique 64-bit identifier associated with a Fibre Channel adapter
port. The WWPN is assigned in an implementation-independent and protocol-independent
manner. See also worldwide node name.
World Wide Web (web, WWW)
A network of servers that contain programs and files. Many of
the files contain hypertext links to other documents available through
the network.
Subscribe to this information