A computer enthusiast who
uses his or her knowledge and means to gain unauthorized access to protected
resources.
HAL
See hardware abstraction
layer (HAL).
half-adjust
A method of rounding
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
Pertaining to data
communications that can be sent in only one direction at a time.
Contrast with duplex.
half-index down
In the
OfficeVision program, pertaining to a control character that prints text
one-half line down. See also
subscript.
half-index up
In the OfficeVision
program, pertaining to a control character that prints text one-half line
up. See also superscript.
half-justify
In the OfficeVision
program, to print text using half as many additional spaces as would be
required if the line were right-justified. The right margin is less
ragged than it would be if the line were only
left-justified.
half-session
In SNA, one of the
locations in a logical connection in a network. See also
session.
halfword binary
In DB2 UDB for
AS/400, a binary number with a precision of 15 bits.
halt indicators
In RPG, an
indicator that stops the program when an unacceptable condition occurs.
Valid halt indicators are H1 through H9.
handle
(1) In application programming
interfaces, a variable that represents an object, an instance of an
application using some function, or a processing session.
(2) In DCE Remote Procedure Call
(RPC), an opaque reference to information. See binding
handle, context handle, interface handle,
name service handle, and thread handle.
(3) In MQSeries, the identifier or
token by which a program accesses an MQM object. See also
connection handle and object
handle.
handle cursor
A pointer that
keeps track of the current exception handler. Contrast with resume
cursor.
handler
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.
handset
The part of a telephone
used for talking and listening.
Hangeul
A written language of
Korea. Each Hangeul character is composed of two to six Jamo
characters.
Hanja
Chinese characters used in
Korean written language.
hardcopy
A printed copy of
machine output in a visually readable form, such as printed reports, listing,
documents, and summaries. Contrast with
softcopy.
hard-copy reference
In the
OfficeVision program, a description of printed mail that is kept on the system
with electronic mail. This allows you to keep track of both types of
mail.
hard disk
A nonremovable storage
medium used for storage of data on a personal
computer.
hard link
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. Contrast with symbolic
link.
hardware
Physical equipment,
rather than programs, procedures, rules, and associated
information.
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. See also application programming
interface (API) and device independence.
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. See also mode-2 character and
mode-3 character.
hash
See hash
value.
hashing
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.
hash join
A method for joining
two or more files together that uses a hash value to find the matching
keys.
hash table
The arrangement of
memory records. See also hashing.
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.
HCF
See Host Command
Facility (HCF).
HCP
See host command
processor (HCP).
HCP emulation
See host
command processor emulation (HCP emulation).
head
A device that reads, writes,
or erases data on a storage medium.
header
(1) In the OfficeVision
program, one or more lines of text that prints at the top of a
document. For example, the header could be the subject of the document,
the date, the page number, an outline heading, or the document ID.
Contrast with footer.
(2) In disk management, the 8-byte
portion of the 520-byte disk sector used by the operating system for control
and access information. See include statement.
(3) The portion of a message that
contains control information such as one or more destination fields, the name
of the originating station, and the priority level for the
message.
header fragment
The first
fragment in a series of fragments.
header label
A special set of
information on a diskette or tape that describes the contents of the diskette
or tape.
header record
A record that
contains information, such as customer name and customer address, that is
common to detail records. Contrast with detail
record.
heading level
In the OfficeVision
program, the arrangement of topic headings as if they were organized in an
outline.
heading record
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.
heap
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. See
dynamic storage.
heap identifier
A number that
identifies a heap within its activation group.
heartbeat
In software products, a
signal that one entity sends to another to convey that it is still
active.
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.
Contrast with released
state.
help level specifications
In a display
file, data description specifications coded between the record and field level
that define areas on the screen and associate help information with those
areas. See also file level specifications, field level
specifications, join level specifications, key field
level specifications, record level specifications, and
select/omit level specifications.
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.
heterogeneous
A collection of
dissimilar host computers such as those from different manufacturers.
Contrast with homogeneous.
heuristic decision
The decision
of an operator to force a commit or rollback of a logical unit of work in only
part of a transaction program network that is using the two-phase commit
protocol.
hex
See
hexadecimal.
hexadecimal
Pertaining to a
numbering system with a base of 16.
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.
HFS
See hierarchical file
system (HFS).
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 field
A field in a display
file that is passed to and from the program but is not sent to the
display.
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.
hierarchical file system (HFS)
A part
of the 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 end user is a
hierarchical directory structure similar to IBM
DOS.
hierarchical storage management (HSM)
In AS/400
storage management, an automatic method to manage and distribute data between
the different storage layers. The storage layers can include
high-performance disk units, compressed disk units, and tape library
devices.
hierarchy
In COBOL, a set of
entries that includes all subordinate entries to the next equal- or
higher-level number.
high convergence
In the DCE Cell
Directory Service (CDS), a setting that controls the degree to which CDS
attempts to keep all replicas of a directory consistent. High
convergence means CDS makes one attempt to propagate an update to all replicas
immediately. See low convergence and medium
convergence.
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, such as RPG, COBOL, and C, used to write computer
programs.
high-level language (HLL) pointer
A source
pointer that the programmer declares in the user
program.
highlight
To define text to be
shown in contrast with other text by underlining, italics, bold-face; or
on a display, high-intensity (brightness of characters), blinking, or reverse
image. You can highlight words, parts of words, or information typed
into a form using the text definition function of
OfficeVision.
high-performance file system (HPFS)
In the OS/2
operating system, 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 routing (HPR)
An
addition to the Advanced Peer-to-Peer Networking (APPN) architecture that
enhances data routing performance and reliability, especially when using
high-speed links.
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 input/outout
processors (IOPs) and other system units.
Hiragana
A graphic character set
that is used to write Japanese words phonetically. This set of
characters is used as word endings when writing in Kanji. Contrast with
Katakana.
histogram
(1) 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.
(2) 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.
history log
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.
HLL
See high-level language
(HLL).
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.
home cell
In the Distributed
Computing Environment (DCE), a synonym for local
cell.
home directory
A directory
associated with a user that becomes the user's initial current directory
when a user job is started.
home location
In Backup Recovery
and Media Services, the storage location where available media is stored
awaiting reuse. Typically, this is the on-site tape inventory.
See also location and storage
location.
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 page
The initial Web page
that is returned by a Web site when a user specifies the URL for the Web
site. (For example, if a user specifies the URL for the IBM AS/400 Web
site, which is http://www.as400.ibm.com,
the Web page that is returned is the home page for that site.)
Essentially, the home page is the entry point for accessing the contents of
the Web site. The home page is sometimes called the welcome
page or the front page.
home position
(1) In Client Access,
the first position of the first input field on the display.
(2) In the OfficeVision
program, the row and column where the cursor was positioned when the display
was last shown.
(3) The position (farthest
left) to which the print head moves after the printer is turned on and the
Stop or Reset button is pressed.
(4) The first item in a list
or the first line of help information.
home system
The first system in a
chain of systems that are linked by any combination of TELNET and pass-through
requests.
homogeneous
A collection of
similar host computers such as those of one model of one manufacturer.
Contrast with heterogeneous.
hook
In CoOperative Development
Environment/400, the location in a compiled program where the compiler inserts
an instruction that allows the user to later interrupt the program (by setting
breakpoints) for debugging purposes.
hop
(1) The transmission from one
location to the next in a network.
(2) An intermediate connection in a
string of connections that links two network
devices.
hops
The number of systems that a
distribution passes through to its
destination.
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.
host
(1) The controlling or
highest-level system in a data communications configuration; for example,
an AS/400 system is the host system for the work stations connected to
it.
(2) In a cooperative processing
environment, the system running the server program with which the CoOperative
Development Environment/400 session communicates.
(3) In TCP/IP, any system that has at
least one internet address associated with it. A host with multiple
network interfaces may have multiple internet addresses associated with
it. The host can be (a) a client, (b) a server, or (c) both a client
and a server simultaneously.
host centric application
In
VisualAge RPG, an application in which the user's program logic is stored
and run on the host.
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 an AS/400 system or other systems as if
they were using remotely attached 5250-type display stations. See also
distributed host command facility
(DHCF).
host command processor emulation (HCP emulation)
A
function of the Point-of-Sale Utility licensed program that allows the AS/400
system to appear to the host command processor (HCP) in a point-of-sale system
as if the AS/400 system were the System/370 host
system.
host command processor (HCP)
The SNA
logical unit of the programmable store system store
controller.
host ID
(1) In the Distributed
Computing Environment (DCE), a synonym for network address.
(2) 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). See also
internet address and network
ID.
host language
In DB2 UDB for
AS/400 SQL, any programming language, such as C, COBOL, and RPG, in which you
can embed SQL statements.
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
In the Internet suite
of protocols, the name that is given to a machine. Sometimes, "host
name" is used to mean fully qualified domain name (FQDN). Other
times, it is used to mean the most specific subname of a fully qualified
domain name. For example, if rchland.vnet.ibm.com
is the fully qualified domain name, either of the following can be considered
the host name: rchland.vnet.ibm.com,
rchland.
host print transform
An Operating
System/400 print function that converts an SNA character string (SCS) data
stream into an ASCII data stream. The ASCII data stream is then
formatted and sent to an ASCII printer through one or more hardware
connections, such as Client Access, 3477, or 3487 work stations. This
single location of the transform allows for consistent ASCII printing through
any of the hardware connections.
host program
In DB2 UDB for
AS/400, a program written in a host language that contains embedded SQL
statements.
host structure
In a DB2 UDB for
AS/400 SQL application program, a structure referred to by embedded SQL
statements. In RPG, this is called a data structure; in C, this is
known as a structure; in COBOL, this is called a group
item.
host system
(1) The primary or
controlling computer in a communications network. See also control
station.
(2) In TCP/IP, a computer that
is part of a network as a peer system.
host table
A list of host names
and associated Internet Protocol (IP) addresses for an Internet Protocol (IP)
network.
host variable
In a DB2 UDB for
AS/400 SQL application program, a variable referred to by embedded SQL
statements. In RPG, this is called a field name; in C, this is
known as a variable; in COBOL, this is called a data
item.
hot backup
In a remote journal
network, pertaining to the function of replicating an application's
dependent data from one primary AS/400 to a backup AS/400. If the
primary system fails, you can perform processing on the backup
system.
hot key
(1) A key sequence used to
shift operations between different applications or between different functions
of an application.
(2) To jump, or hot key, from a host
session to an application on a workstation, or from the workstation to the
host session.
hotlink
(1) A function of RUMBA/400
that uses dynamic data exchange to copy information from an AS/400 database
file to personal computer applications.
(2) In VisualAge RPG, a function
used to copy information to and from OS/2 programs, to and from Microsoft
Windows programs, or to and from OS/2 and Microsoft Windows
programs.
hotspot
In RUMBA/400, an area of
the display that, when clicked on, calls a
macroinstruction.
HPFS
See high-performance
file system (HPFS).
HPR
See high-performance
routing (HPR).
HRI
See human readable
interpretation (HRI).
HSL
See high-speed link
(HSL).
HSM
See hierarchical storage
management (HSM).
HTML
See hypertext markup
language (HTML).
HTTP
See Hypertext Transfer
Protocol (HTTP).
HTTP method
An action that is
used by the Hypertext Transfer Protocol. HTTP methods include GET,
POST, and PUT.
HTTPS
See Hypertext
Transport Protocol Secure (HTTPS).
HTTP Server for AS/400
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 AS/400, which supports the Secure
Sockets Layer (SSL) protocol, provides secure communications between an AS/400
server and an SSL-capable WWW browser.
hue
The gradual variations of
colors such as blue, green, red, yellow, and so
on.
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.
hypertext
(1) A way of presenting
information online with connections (called hypertext links) between one piece
of information (called hypertext nodes) and another.
(2) A weblike structure of
nonlinear information nodes linked together by author-defined associations
that allow users to freely select nodes of
interest.
hypertext link
The connection
between one hypertext node and
another.
hypertext markup language (HTML)
A markup
language that is specified by a Standard Generalized Markup Language (SGML)
document type definition (DTD) and that is understood by all World Wide Web
servers. For example, HTML controls the format of text and the position
of form input areas and navigable 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)
In the
Internet suite of protocols, the protocol that is used to transfer and display
hypertext documents.
Hypertext Transport Protocol Secure (HTTPS)
A TCP/IP
protocol that is used by World Wide Web servers and Web browsers to transfer
and display hypermedia documents securely across the
Internet.
hypervisor
A specialized portion
of Licensed Internal Code that enables logical partitioning.