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L1 cache. The first cache accessed when a storage reference occurs.

L2 cache. The cache that is accessed, on certain RS/6000 models, if the L1 cache lookup results in a cache miss. Normally, the L2 cache is larger and slower than the L1 cache, but faster than RAM.

label. (1.) A name in the disk or diskette table of contents that identifies a file. (2.) The field of an instruction that assigns a symbolic name to the location at which the instruction begins. (3.) In programming languages, a construction naming a statement and including an identifier. See also file name. (4.) An identifier followed by a colon, used to identify a statement in a program. Usually the target of a goto or switch statement. See also statement label.

labeled statement. (1.) A programming language statement that contains one or more identifiers followed by a colon and a statement. (2.) A possibly empty statement immediately preceded by a label.

LAN. See local area network.

landscape display. A rectangular display wider than it is high. See also portrait display.

landscape left. A page orientation such that the left side of the printed image is at the trailing edge of the paper as it emerges from the printer.

landscape right. A page orientation such that the right side of the printed image is at the trailing edge of the paper as it emerges from the printer.

LAP. See link-access procedures.

LAPB. Link-access procedure balanced. See also link-access procedures.

last line mode. A command mode in the vi editor. Enables the user to enter a command at the bottom of the screen. See also text input mode.

latency. The time from the initiation of an operation until something actually starts happening (for example, data transmission begins).

layout. The arrangement of printed matter on the page, including margins, line spacing, type specification, header and footer information, indents, and more. Synonymous with geometry.

lb. See pound.

LC. See link control.

LCN. See logical channel number.

leaders. An evenly spaced row of dots used in a table of contents to guide the eye from the title to the page number.

leaf. A page of text. See also page.

leaf delta. A set of changes to the source code saved in the Source Code Control System (SCCS) file.

leaf entry. A directory entry that has no subordinates. It can be an alias entry or an object entry.

leap seconds. An infrequent adjustment to UTC to account for the irregularity of the earth's rotation.

leased facility. Synonym for nonswitched line.

leaves. On a widget tree, widgets with no children. See also widget tree.

LED. See light-emitting diodes.

left-adjust. The process of aligning lines of text at the left margin or at a tab setting such that the leftmost character in the line or file is in the leftmost position.

left margin. The area on a page or screen between the left edge and the leftmost character position on the page or screen.

length specification. A source language specification of the number of bytes to be occupied by a variable.

letter. An uppercase or lowercase character from the set A through Z.

level. (1.) The version of a software application program. (2.) See also higher layer. (3.) In X.25 communications, see also physical level, packet level, and frame level.

level 1. Synonym for physical level.

level 2. Synonym for frame level.

level 3. Synonym for packet level.

lexical analyzer. A program that analyzes input and breaks it into categories, such as numbers, letters, or operators.

lexical element. In Ada language, an identifier, a literal, a delimiter, or a comment.

lexical level. The depth to which routines are nested within one another, which determines the scope of the identifiers declared within those routines.

lexical scope. The portion of a program or segment unit in which a declaration applies. An identifier declared in a routine is known within that routine and within all nested routines. If a nested routine declares an item with the same name, the outer item is not available in the nested routine.

library. (1.) A collection of functions, calls, subroutines, or other data. (2.) A data file that contains copies of a number of individual files and control information that allows them to be accessed individually. (3.) In Ada-language library management, a database that stores the various intermediate code files produced by the compiler and records the dependency and order of compilation information as required by the Ada language specification. When compiling a unit that depends on other (previously compiled) units, the required dependency information (such as the package specification of a unit that is included with a with clause) is obtained from the library. Similarly, when an Ada program unit is to be linked, the library specifies the set of units that must be included to create an executable image.

library component. In Ada language, a package body, package specification, subprogram body, subprogram specification, object form module, or linked object module that resides in a library.

library list file. In Ada language, a text file containing the name of one or more sublibraries comprising an Ada program library.

library unit. In Ada language, one of five syntactic entities: a subprogram declaration, a package declaration, a generic declaration, a generic instantiation, or a subprogram body in the case where there is no corresponding subprogram declaration. As the name implies, a library unit resides in the Ada program library. The significance of library units is that they may be referenced by other independently compiled units. This reference may either be explicit (referenced via a with clause) or implicit (such as the reference of a package body to its specification).

license. An instance of permission to use a licensed software product or service. Sometimes, a user needs more than one license to use a product.

license annotation. A special data string that modifies the use of a license in a manner defined by the vendor of the software product.

license database. The database of licenses maintained by a license server. The license database file-lic_db-resides in the /usr/lib/netls/conf directory.

license information. The information that describes licenses. This information consists of the product name, the product version, the number of licenses, the license type, the start and end dates of the licenses, the target type, the target ID, and a time stamp.

license password. A string encoded with license information for a software product.

license server daemon. A software program that administers licenses for software products, invoked with the command netlsd. The netlsd command can be found in the /usr/lib/netls/bin directory.

licensed product. A software product that has been enabled by a software vendor for use with the License Use Management system. Enablement allows a vendor to enforce end-user compliance to their license agreement.

License Use Management. A run-time license-management application based on Gradient Technologies' Version 2.0.1 (Version 1.1.2a) of the Network Licensing System. The system allows software vendors to bundle compliance mechanisms with their software. In tracking license usage, License Use Management allows customers to easily comply with their software license agreements.

License Use Management Test Product. The product used by the ls_tv tool to verify that license servers are working properly.

licensed program (LP). (1.) A software program that remains the property of the manufacturer, for which customers pay a license fee. (2.) A separately priced program and its associated materials that bear a copyright and are offered to customers under the terms and conditions of a licensing agreement.

lifetime analysis. The process of inspecting references to variables to determine whether the final assignment to a variable needs to be stored or can be discarded.

ligature. Two (or occasionally more) characters printed together so they are connected.

light-emitting diodes (LED). A semiconductor chip that gives off visible or infrared light when activated. An LED is often used to display operator information.

lighted programmable function keyboard (LPFK). An input device used primarily in graphic applications and that has lighted keys under control of an application program.

limited interface. A set of system calls that provides a limited function interface. See also interface and extended interface.

limited subset. A small part or simpler version of a larger set of data or programs.

limited type. In Ada language, a type for which neither assignment nor the predefined comparison for equality is implicitly declared. All task types are limited. A private type can be defined to be limited. An equality operator can be explicitly declared for a limited type.

line. (1.) A horizontal display on a screen. (2.) The part of a data circuit that connects to data circuit-terminating equipment (DCE), or to data switching exchange (DSE), or that connects several DCEs or DSEs. (3.) A string of characters accepted by a system as a single block of input from a workstation, such as all characters entered before a carriage return. (4.) See X.25 line.

line adapter. A functional unit that converts the serial-by-bit input to a station. See also communications line adapter.

line editor. An editor that displays data one line at a time and that allows data to be accessed and modified only by entering commands.

line height. The vertical measurement of a line of text, measured from the bottom of one line to the bottom of the next line. Line height is usually expressed in points.

line number. For the Ada-language debugger, a line relative to the Ada compilation that contains the specified compilation unit.

line of memory. The section of memory that corresponds to a cache line, which corresponds to a single virtual-memory address tag.

line pacing. The sending of a line followed by a waiting interval before continuing transmission. See also pacing.

line printer. A printer that prints output, one line of characters at a time, as a unit. Output of line printers is in constant-width characters.

line speed. (1.) The rate at which data is transmitted from one point to another over a telecommunication line. (2.) The number of binary digits that can be sent over a telecommunication line in one second, expressed in bits per second (bps). Synonym for speed.

line switching. Synonym for circuit switching.

linear interpolation. A method of approximating data values by assuming that they lie along a straight line. Typically, the two end data points are known. For example, if A is the value at a, and B is the value at b, and a<t<b, then the value C at t is (from the two-point formula): B - A divided by b - a, multiplied by t - D, added to A.

linefeed. An ASCII character that causes an output device to move forward one line.

linestyle. The pattern used to draw a line. A linestyle might be solid or broken into a pattern of dashes.

linewidth. The width of a line in pixels.

link. (1.) In the file system, a connection between an i-node and one or more file names associated with it. (2.) In data communications, a transmission medium and data link control component that together transmit data between adjacent nodes. (3.) In programming, the part of a program that passes control and parameters between separate portions of the computer program. (4.) To interconnect items of data or portions of one or more computer programs, such as linking object programs by a linkage editor or linking data items by pointers. (5.) See X.25 link. (6.) See hypertext link.

link-access procedures (LAP or LAPB). In X.25 communications, the link level elements used for data interchange between a DCE and a DTE operating in user classes of service 8 to 11, as specified in CCITT Recommendation X.1. LAPB is a duplex, asynchronous, symmetric protocol, used in point-to-point communication. See also LAPB.

link address. An address assigned at initialization that identifies a channel or control unit and allows it to send and receive frames and perform I/O operations. A set of computers sharing a network that does not include bridges of wide area network links.

link anchor. The reference point giving the location of a particular link.

link control (LC). See logical link control.

link descriptor. In ODM, a named variable of type link used to define a relationship between an object in an object class and an object in another object class. See also descriptor.

link-editing. To create a loadable computer program by means of a linkage editor.

link level. See frame level.

link station. The part of data link control that is responsible for the transfer of data on a single logical link.

link target. See target.

link trace. A sequential log of events that occur on the link. This log can help determine the source of a recurring error.

linkable. The state of an Ada-language program when all its compilation-unit dependencies have been resolved. To produce an executable file, the compiler does not need to do any translation of Ada source; it only needs to call the linkage editor.

linkage editor. A program that resolves cross-references between separately compiled object modules and then assigns final addresses to create a single relocatable load module. If a single object module is linked, the linkage editor simply makes it relocatable.

linker. See linkage editor.

LIS. Logical IP Subnet. An LIS is comprised of some number of ATM stations. LISs are analogous to traditional LAN segments.

LISP. A programming language designed for list processing and used extensively for artificial intelligence problems.

LISP code. Program instructions written in the LISP programming language.

LISP mode. For text editors, a mode in which symbols used in the LISP programming language, such as ( (left parenthesis) and ]] (double right bracket), are treated as symbols, not as editor commands.

list. (1.) A data object consisting of a collection of related records. (2.) An ordered set of data.

list-directed. In FORTRAN, an input/output specification that uses a data list instead of a FORMAT specification.

list-directed data. In FORTRAN, data that is transferred between main storage and an I/O device according to the length and type of variables in the I/O list. See also formatted data.

list fields. See indexed fields.

listen. In the X.25 API, to be prepared to receive incoming calls that satisfy criteria specified in an entry in the routing list, through a specified X.25 port.

listen identifier. In the X.25 API, an identifier used to listen for and receive an incoming call.

listening. Programs waiting for network communication on a given socket are listening on that socket. See also socket and port.

literal. (1.) A symbol or a quantity in a source program that is itself data, rather than a reference to data. (2.) In programming languages, a unit that directly represents a value. For example, 14 represents the integer 14. (3.) In Ada language, a literal represents a value literally, that is, by means of letters and other characters. A literal is either a numeric literal, an enumeration literal, a character literal, or a string literal.

literal string. A string that does not contain pattern-matching characters and can therefore be interpreted just as it is. Contrast with regular expression.

little endian. An attribute of data representation that reflects how multi-octet data are stored in memory. In little endian representation, the lowest addressed octet of a multi-octet data item is the least significant. See also endian and big endian.

little endian order. The method of storage in which integer values are stored least significant byte first. See also big endian order.

LLB. See Local Location Broker.

llbd. The local location broker daemon.

LLC. See logical link control.

LMS. Line monitoring system.

LNS. See LU network services component.

load. (1.) To transfer programs or data from storage into an area of memory where the program can be run or where the data can be manipulated. (2.) To place a diskette into a diskette drive. (3.) To insert paper into a printer. See also call.

load level. The balance of work between processing units, channels, or devices.

load module. See run file.

load-store bound. Where the delay in a series of computations is caused by the amount of data that must be loaded into registers or stored back into memory.

loader. A program that reads run files into main storage so that the files can be run.

local. (1.) Pertaining to a device, file, or system that is accessed directly from your system, without the use of a communications line. Contrast with remote. (2.) Pertaining to information that is defined and used only in one subdivision of a computer program.

local address. The address specified for the current network or host. The local address is usually referred to as the local host address or the local network address to differentiate the two types.

local area network (LAN). (1.) A network in which communications are limited to a moderate-sized geographic area (1 to 10 km) such as a single office building, warehouse, or campus. A local network services a facility without the use of common carrier facilities, although they may be interconnected using common carriers. A local network depends upon a communications medium capable of moderate to high data rate (1 to 20 M bytes per second), and normally operates with a consistently low error rate. (2.) A data network in which serial transmission is used for direct data communication among data stations.

local cell. The cell to which the local machine belongs. See also foreign cell.

local echo. On a communications workstation, a situation in which each signal is displayed twice, once when entered at the local workstation and again when returned over the communications link.

local host. In TCP/IP, the host on the network at which a particular operator is working. Synonymous with current host.

local listen. A link station at the local node that is waiting for an incoming call from a remote station.

Local Location Broker (LLB). (1.) Part of the NCS Location Broker. A server that maintains information about objects on the local host. The LLB also provides the Location Broker forwarding facility. (2.) A service that provides an interface to the global location broker from the License Use Management server. The LLB daemon (llbd) has no information about network-wide services. It runs continuously in the background to intercept and forward information to the glbd. See also Location Broker and Location Broker Client Agent.

local name. A name that is meaningful and usable only from within the cell where the entry exists. The local name is a shortened form of a global name. Local names begin with the prefix /.: and do not contain a cell name.

local pacing. Pacing generated by the local system in an attempt to control the output from the remote system that is input to the local system. See also pacing.

local scope. A name declared in a block has local scope and can only be used in that block.

local storage. A device accessed directly (without telecommunications) from the user's system, where information can be retained and later retrieved.

local variable. A symbol defined in one program module or procedure that can only be used within that program module or procedure.

locale. A subset of a user's environment that defines conventions for a specified culture, such as time formatting, numeric formatting, monetary formatting, and character classification, conversion, and collation.

locality of reference. The degree to which a running program makes use of a compact range of addresses for instructions and/or data.

Location Broker. In NCS, a set of software including the Local Location Broker, the Global Location Broker, and the Location Broker Client Agent. The Location Broker maintains information about the locations of objects. See also broker, Local Location Broker, and Location Broker Client Agent.

Location Broker Client Agent. Part of the NCS Location Broker. Programs communicate with Global Location Brokers and with remote Local Location Brokers using the Location Broker Client Agent. See also Local Location Broker and Location Broker.

location code. A path from the adapter in the processor through the signal cables and fan out box, if there is one, to the device or workstation. The code consists of four fields of information: Drawer, Slot, Connector, and Port.

location counter. A counter in the assembler that denotes the next byte available for code allocation. The location counter assigns storage addresses to program statements. See also instruction address register.

locator. In computer graphics, an input device that provides coordinate data; for example, a mouse, tablet, or thumb wheel.

locator resolution. The density of points on a locator device.

locator sample rate. The rate of input from a locator device. Synonymous with sample rate.

lock. A mechanism with which a resource is restricted for use by the holder of the lock. See also record lock.

LOCK. See Lock Service.

Lock button. In CDE, a Front Panel control used to lock the screen.

lock file. In multiprocess applications, a system file on disk that the sharing processes use to control their access to shared data or devices.

Lock Service (LOCK). The component of Encina Base that enables transactions to lock resources before accessing or modifying them.

log. (1.) To record. For example, to record all messages on the system printer. (2.) A list of messages, such as an error log. (3.) A collection of messages or message segments placed in an auxiliary storage device for accounting or data collections purposes.

log file. (1.) The text file that records messages and errors from the license server, and sometimes from licensed products, which resides in the /usr/lib/netls/conf directory. (2.) In Ada language, a file that contains a record of your commands and comments and the debugger's responses. This log can be used for later analysis, for documenting program behavior, or for making comparisons after program modification.

log force. An action that causes all pending log records to be written to permanent storage. A log force is usually associated with committing a transaction, and ensures that the log records associated with that transaction are actually present in the log. Until a log force is done, these records might only be stored in memory and might, therefore, be vulnerable to system failures.

log force groups. A logical association of the log records associated with different processes. Grouping the log records associated with all processes spawned by a specific transaction provides a convenient way to ensure that all of the log records associated with any processes acting on behalf of a specific transaction can be referred to with a single expression or operation.

log in. (1.) To begin a session at a display station. (2.) The act of gaining access to a computer system by entering identification and authentication information at the workstation.

log off. To end a session with a computer system at a display station.

log on. See log in.

log out. See log off.

log record. A predefined structure into which the log data is formatted. Records have a specific size and format, and contain a certain set of related information. A log record can be identified by its log sequence number (LSN).

log volume. An abstract representation of disk space that is used for storage by the Encina log server. There are two types of log volumes: permanent and archival. Permanent volumes can be stored on file or disk devices. Archival volumes can only be stored on file devices. Internal log server data and log file groups must be stored on permanent volumes. Log archive groups must be stored on archival volumes. See also volume, logical volume, and physical volume.

logarithm. A mathematical operation related to the base of a numbering system.

logger. (1.) A functional unit that records events and physical conditions, usually with respect to time. (2.) A program that enables a user entity to log in (for example, identify itself, its purpose, and time of entry) and log off with the corresponding data. This enables the appropriate accounting procedures to be carried out in accordance with the operating system.

logical channel. In X.25 communications, a means of two-way simultaneous transmissions across a data link, comprising associated send and receive channels. A logical channel can represent the path that data travels from its origin to the network or from the network to its destination. See also channel.

logical channel number (LCN). An umber that uniquely identifies a logical channel.

logical constant. A constant with a value of true or false.

logical device. (1.) A file for conducting input or output with a physical device. (2.) A file for mapping user I/O between virtual and real devices.

logical expression. An expression consisting of logical operators, relational operators, or both that can be evaluated to a value of either true or false.

logical link. The logical connection between an application on the S/370 and an application on the workstation.

logical link control (LLC). In a local area network, the protocol that governs the assembling of transmission frames and their exchange between data stations, independently of the medium access control protocol. See also medium access control.

logical name. A name assigned to a device that distinguishes it from all other device instances in the system. It is the name used to refer to a particular device. For example, "tok0" can refer to a token-ring adapter. This is the same as "device name," which is a field in the Customized Devices Object Class. See also device name.

logical network. A subnetwork of machines set up to function as a whole and separate network. A logical network usually functions as a subnetwork of a larger physical network.

logical operation. An operation that follows the rules of Boolean logic.

logical operator. A symbol that represents an operation, such as AND, OR, or NOT, on logical expressions.

logical partition (LP). (1.) One to three physical partitions (copies). The number of logical partitions within a logical volume is variable. (2.) A fixed-size portion of a logical volume. A logical partition is the same size as the physical partitions in its volume group. Unless the logical volume of which it is a part is mirrored, each logical partition corresponds to, and its contents are stored on, a single physical partition. See also logical volume.

logical primary. A primary that can have a value of true or false.

logical resource. A software construct, such as a lock or a buffer, that is required for the execution of a program and is in limited supply.

logical storage. A conceptual storage layout in which an application maps first into logical addresses, which are then mapped into real addresses by control blocks.

logical type. A data type that contains the values of true and false.

logical unit (LU). (1.) A type of network addressable unit that enables end users to communicate with each other and gain access to network resources. (2.) In SNA, a port through which an end user accesses the SNA network to communicate with another user, and through which the end user accesses the functions provided by system services control points (SSCPs). An LU can support at least two sessions, one with an SSCP and one with another LU, and may be capable of supporting many sessions with other LUs.

Logical Unit Type 1 (LU1). An SNA session that supports communication between an application and multiple input/output devices. This communication could occur in an interactive or batch environment.

Logical Unit Type 2 (LU2). An SNA session that uses a 3270 device data stream to support communication between an application and a display.

Logical Unit Type 3 (LU3). An SNA session that uses a 3270 device data stream to support communication between an application and a printer.

Logical Unit Type 6.2 (LU6.2). (1.) An SNA session between two applications in a distributed data processing environment. (2.) The LU type used for SNA advanced program-to-program communications (APPC). See also peer-to-peer communications.

logical volume (LV). (1.) A collection of physical partitions organized into logical partitions all contained in a single volume group. Logical volumes are expandable and can span several physical volumes in a volume group. (2.) A set of logical partitions, each of which is stored on one or more physical partitions from one or more of the physical volumes of a given volume group. A logical volume has a device name (of the form /dev/hdn) and contains a single file system. See also log volume, migration installation, logical partition, and volume group.

Logical Volume Manager (LVM). Manages disk space at a logical level. It controls fixed-disk resources by mapping data between logical and physical storage and by allowing data to span multiple disks and to be discontiguous, replicated, and dynamically expanded.

login directory. The directory you access when you first log in to the system.

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

login session. The period of time during which a user of a workstation can communicate with an interactive system, usually the elapsed time between log in and log off.

login shell. The shell that is started when a user logs into the computer system. The login shell for a particular user is determined by the entry in the /etc/passwd file for that user. See also shell.

long. (1.) In ODM, a terminal descriptor type used to define a variable as a signed 4-byte number. See also terminal descriptor. (2.) A signed 4-byte number.

long constant. A 4-byte integer constant followed by the letter "l" or "L."

long queue status. Synonym for long status.

long status. A detailed, multiline status that contains more information about each job than the normal short status. Synonymous with long queue status.

loop. (1.) A sequence of instructions performed repeatedly until an ending condition is reached. (2.) A closed unidirectional signal path connecting input and output devices to a system.

loop collapse. In nested array-processing loops, an optimization that collapses the nested loops into a single loop with an iteration count that is the product of the iteration counts of the original loops, and that adjusts array indices appropriately.

loop defactorizing. An optimization that removes an invariant factor from a loop that sums calculations into a scalar. The summation scalar can be multiplied by the factor on exit from the loop.

loop elimination. A form of loop unrolling in which the loop is completely unrolled, and references to loop index within the unrolled loop are replaced by constant values.

loop fusion. An optimization that takes the bodies of loops with identical iteration counts and fuses them into a single loop.

loop nest reordering. An optimization that changes the order of loops within a loop nest, to achieve stride minimization or to eliminate data dependencies.

loop overhead. The CPU time used by a loop that cannot be attributed to computations within the loop.

loop peeling. An optimization that improves the performance of a loop that maps an array to a cylindrical coordinate system.

loop rerolling. An optimization that transforms user-unrolled loops into their original, unrolled equivalents, so that other optimizations can be attempted.

loop unrolling. An optimization that increases the step of a loop, and duplicates the expressions within a loop to reflect the increase in the step. This can improve instruction scheduling and memory access time.

looping statement. A statement that runs any number of times, depending on the value of a specified expression.

low-order. Least significant; rightmost. For example, in a 32-bit register (0 through 31), bit 31 is the low-order bit.

LP. See licensed program.

LPFK. See lighted programmable function keyboard.

LPM. Lines per minute. The number of lines a printer can print in one minute.

LPR. Line Printer Server.

LQ. Letter quality.

LRU. Least recently used.

ls_admin. In License Use Management, the software program used to modify a license server database, invoked with the command ls_admin, which is located in the /usr/lib/netls/bin directory.

ls_rpt. In License Use Management, the software program that reports on the history of license server events, invoked with the command ls_rpt, which is located in the /usr/lib/netls/bin directory.

ls_stat. In License Use Management, the software program that reports on the status of licenses, invoked with the command ls_stat, located in the /usr/lib/netls/bin directory.

ls_tv. In License Use Management, the network license server daemon test and verification tool, invoked with the command ls_tv, located in the /usr/lib/netls/bin directory.

lsb. Least significant bit

LSB. Least significant byte.

LU. See logical unit.

LU1. See Logical Unit Type 1.

LU2. See Logical Unit Type 2.

LU3. See Logical Unit Type 3.

LU6.2. See Logical Unit Type 6.2.

LU, dependent. A logical unit that cannot start a conversation but must wait for the host system to start the conversation.

LU, independent. A logical unit that can start a conversation with another logical unit.

LU-LU session. In SNA Server, a session between two logical units (LUs) of the same type that supports communication between two end users, or between an end user and an LU services component.

LU network services component (LNS). Begins and ends LU-LU sessions in response to requests from the resource manager and from the remote LU. It also activates and deactivates CP-LU sessions.

lvalue. (1.) An expression that represents a data object that can be both examined and altered. (2.) The left-hand part of an expression.

LV. See logical volume.

LVM. See Logical Volume Manager.

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