l

L

language: (1) The written and spoken methods of combining words to create meaning used by a particular group of people. (2) For the Macintosh script management system, a particular implementation of a writing system. Languages within a writing system usually share a character set but differ in rules of composition. For example, English and Spanish are two languages within the Roman writing system.

language code: A number used to indicate a particular written version of a language on the Macintosh. Constants are defined for each of the language codes recognized by the Macintosh script management system.

LAP Manager

See: Link-Access Protocol (LAP) Manager

large character set: A character set with more than 256 characters. Japanese, Chinese, and Korean writing systems have large character sets. The script system for such a writing system requires 2-byte character codes, and is therefore called a 2-byte script system.

large-catalog mode: A set of algorithms used by certain components of a PowerTalk system when retrieving information from large catalogs and displaying that information to the user.

last-in, first-out (LIFO): Characteristic of a queue in which the last item put into the queue becomes the first item to be taken out of it

launch time: The period during which the Process Manager builds the process for a program that is starting up

See also: generation time

layer: A mechanism for prioritizing the tracks in a movie. When it plays a movie, the Movie Toolbox displays the movie's tracks according to their layer"tracks with lower layer numbers are displayed first; tracks with higher layer numbers are displayed over those tracks.

layer flag: An element of a face layer that describes the characteristics of one layer of a text face. Layer flags are used primarily to determine the underlining capabilities of the text face.

layout shape: A type of QuickDraw GX shape. The geometry of a layout shape contains a line of text and sophisticated typographic formatting information

See also: glyph shape, text shape, typographic shape

leading: The amount of blank vertical space between the descent line of one line of text and the ascent line of the next line of single-spaced text. In early typesetting, strips of lead were placed between lines of type for spacing, hence the term

See also: line spacing

leading edge: The edge of a glyph that is encountered first when reading text of that glyph's language. For glyphs of left-to-right text, the leading edge is the left edge; for glyphs of right-to-left text, the leading edge is the right edge

See also: trailing edge

leaf atom: A QuickTime atom that contains no other atoms. A leaf atom, however, may contain a table. An example of a leaf atom is an edit list atom. The edit list atom contains the edit list table

See also: container atom

leaf node: A node that contains data records.

leaf procedure: A routine that calls no other routines.

least significant bit: The bit contributing the least value in a string of bits. For example, in the MC680x0 numbering scheme bit number 0 in a byte contributes a value of 20, or 1. Same as low-order bit

See also: most significant bit

left-side bearing: The white space between the glyph origin and the visible beginning of the glyph.

left-to-right caret: A type of caret that, at direction boundaries, appears at the proper caret position for inserting left-to-right text

See also: dual caret, right-to-left caret

letter: A type of message consisting of a defined set of message blocks. A letter is intended to be read by a person

See also: mailer, non-letter message

letter attribute: A piece of information about a letter stored in the letter header or the letter's message summary. Letter attributes include information such as the sender, the subject, the time the letter was sent, and so forth. Not to be confused with attribute.

letter header block: A message block found in every letter. It contains recipient information and letter attributes.

level: A number indicating how many pictures separate a shape from the root picture in a picture hierarchy.

level cap: A cap shape that is not rotated to match the angle of the contour on which it is drawn.

level join: A join shape that is not rotated to match the angle that bisects the corner on which it is drawn.

library

See: import library

library directory: A directory used by an application or other fragment to store import libraries used by that application or fragment. An application's library directory is specified in the application's code fragment resource.

LIFO

See: last-in, first-out (LIFO)

ligature: The combination of more than one letter into a single typographical shape. For example, the ligature '_' results from the combination of the letters 'f' and 'i'.

ligature decomposition: The replacement of ligatures with the glyphs for their component characters during justification.

ligature splitting: The process of separating a ligature into its component glyphs.

line: A graphic image defined by two points: the current location of the graphics pen and its destination. The graphics pen, which can draw with different patterns, hangs below and to the right of the defining points.

linear interpolation: A form of interpolation that uses the calculated mean of two sample points as the interpolated sample point

See also: drop-sample conversion

line breaking: The process of determining the proper location at which to truncate a line of text so that it fits within a given text width.

line direction: Also called text direction, character direction, or simply direction. The direction in which text in a particular language is written and read. The English language has a left-to-right line direction; Arabic and Hebrew have a (primarily) right-to-left line direction

line layout error: The difference between the width of the printed line and the width of the screen line after the printer driver has performed font substitution. Certain printer drivers compensate for this by distributing the error to major glyphs and minor glyphs.

line length: The distance, in points, from the origin of the first glyph on a line through the advance width of the last glyph.

line shape: A shape type that represents a straight line.

line spacing: The vertical distance between two lines of type, measured from baseline to baseline. For example, 10/12 indicates 10-point type with 12 points base to base (that is, with 2 points of leading).

line span: The distance, in points, from the lowest descender on a line to the highest ascender.

link: A data transmission medium shared by nodes and used for communication among these nodes. A link forms the basis for networking these nodes.

linkage area: The area in a PowerPC stack frame that holds the caller's RTOC value and saved values of the Count Register and Link Register

See also: parameter area

link independence: The ability to connect to various types of data links that are installed on a node and to switch among those data links.

Link Register (LR): A register in the PowerPC processor that holds the return address of the currently executing routine.

link time: At generation time, the point at which a linker binds object code with imported libraries to create executable code.

Link-Access Protocol (LAP) Manager: A set of operating-system utilities that makes it possible for the user to select among AppleTalk connection files by using the Network control panel to specify which network is to be used for the node's AppleTalk connection. The LAP Manager provides for AppleTalk's data-link independence.

link-time library

See: definition stub library

list: A series of items displayed within a rectangle. Lists may have zero, one, or two scroll bars.

Listen: An ADB command to a device that instructs it to prepare to receive additional data

See also: Flush, SendReset, Talk

list box: A control that combines a rectangular frame, scroll bar(s), and a scrollable list of items

See also: scroll bar

list box frame: A control that provides an Appearance-compliant border for non-standard list boxes

See also: list box

list definition procedure: A code resource of type 'LDEF' that defines the appearance of a list.

List Manager: A collection of routines that your application can use to create and display lists in your application's windows or dialog boxes.

little arrows: A control that displays a pair of arrows, typically accompanying an edit text field containing a numerical value. Users click the arrows to increment or decrement the value in the text box.

live cache: A QuickDraw GX cache that contains current information. The object associated with the cache has not been changed since the cache was created

See also: dead cache

live dragging: The constantly updated display of the changing values of a track control, such as scroll bar or slider

See also: scroll bar, slider

LLC

See: Logical Link Control (LLC)

load: (1) To move a segment or fragment into RAM. (2) To return an unloaded QuickDraw GX object from external storage to memory. QuickDraw GX automatically and transparently loads and unloads objects in the course of managing memory; an application need never know whether an object it accesses is currently loaded or unloaded.

load directory: The directory that contains a fragment being loaded into memory and prepared for execution.

localization: The adaptation of system software or applications to a particular language or region. Localization involves translating strings and providing proper conventions for sorting, date and time formats, currency and measurement units, calendars, numbers, and other culturally specific items such as icons

See also: internationalization

localized system software: Macintosh system software that has been adapted to a particular language or region. Localization may involve adding a second script system, as in the case of Japanese system software; or it may simply require modifying the U.S. Roman script system, as in the case of French or Turkish system software.

Local Area Network (LAN): \xE6A collection of linked computers and other components, both hardware and software, that can communicate and share resources.

local coordinates: (1) Paired values that specify a size or location in local space. (2) For QuickDraw GX, the coordinate space local to each shape. For example, a shape's geometry is described in local coordinates.

local coordinate system: The coordinate system of a window's graphics port. When the Window Manager creates a window, it places the origin of the local coordinate system at the upper-left corner of the window's port rectangle

See also: global coordinate system

local identity: A number used as shorthand for the name and password of the principal user of a particular computer. A local identity gives the user access to all the services for which names and passwords are stored in the PowerTalk Setup catalog

See also: specific identity

local space: The coordinate system, interior to a view port, resulting from the application of the transform mapping to the geometry of a shape object

See also: device space, geometry space, global space

local variable: A variable allocated and used only within the current procedure.

location name: An identifier for the network location of the computer on which a port resides. The PPC Toolbox provides the location name. It contains an object string, a type string, and a zone. An application can specify an alias for its location name by modifying its type string

See also: port

location record

See: fragment location record

lock: (1) To prevent a relocatable block from being moved during heap compaction. (2) To temporarily prevent a range of physical memory from being paged out or moved by the Virtual Memory Manager. (3) To prevent an object in the QuickDraw GX heap from being moved. You can lock some QuickDraw GX objects and manipulate their properties directly, instead of using functions to copy them into and out of application memory

See also: unlock

locked file: A file whose data cannot be changed.

locked range: A range of bytes in a file whose data cannot be changed.

locked volume: A volume whose data cannot be changed.

lock attribute: When set, this attribute prevents an item in a collection from being replaced.

logical address: A memory address used by code at execution time. The logical address might, in turn, be translated into a physical address by the CPU.

logical block: (1) An abstract location on a storage device, defined by software and independent of the physical characteristics of the device

logical descriptor record: A coerced AE record of type typeLogicalDescriptor that specifies a logical expression"that is, an expression that the Apple Event Manager evaluates to either TRUE or FALSE. The logical expression is constructed from a logical operator (one of the Boolean operators AND, OR, or NOT) and a list of logical terms to which the operator is applied. Each logical term in the list can be either another logical descriptor record or a comparison descriptor record.

logical end-of-file: The position of 1 byte past the last byte in a file; equal to the actual number of bytes in the file.

Logical Link Control (LLC): A data-link standard defined by the Institute of Electrical and Electronics Engineers (IEEE) for use on Ethernet, token ring, FDD I, and certain other data links. At the physical level, these protocols include the 802.3 CSMA/CD protocol, the 802.4 token bus protocol, and the 802.5 token ring protocol. At the data-link level, you access these protocols through the IEEE 802.2 Logical Link Control (LLC) protocol.

logical size: The number of bytes in a memory block's contents.

log on: To connect to a networked file server or to a local machine that requires user authentication. Usually a user must specify a user name and password to be able to log on to a file server.

longword boundary: The memory location that divides two long words.

long date-time record: A data structure that represents date and time as a record rather than a 64-bit long integer.

long date-time value: A 64-bit integer in SANE comp format that represents date and time purely in seconds. This format allows dates and times before and after the range of the date-time record (30,000 B.C. to 30,000 A.D.).

long DDP header: A DDP packet header that includes the source node ID as well as the destination node ID.

long number: A 32-bit signed integer. A fixed- point number with a bias of 0. Long numbers range from _2,147,483,648 to +2,147,483,647. The long number for 1.0 is 0x00000001.

long word: A 32-bit quantity used to store 232 (or 4,294,967,296) values.

long-date-format resource: An international resource of type 'itl1'. The long-date-format resource defines conventions for formatting long dates, including names of days and months. Each installed script system has one or more long-date-format resources.

lookup table: A resource in an aspect template that parses attribute values into properties and properties into attribute values. A lookup table contains an entry for each type of attribute value to be translated into and from properties.

lossless compression: A compression scheme that preserves all of the original data.

lossy compression: A compression scheme that does not preserve the data precisely; some data is lost, and it cannot be recovered after compression. Most lossy schemes try to compress the data as much as possible, without decreasing the image quality in a noticeable way.

low ASCII character set: Same as ASCII character set; the standard set of Roman characters with character-code values from $00 to $7F.

low caret

See: secondary caret

low-level event: The type of event returned by the Event Manager to report very low level hardware and software occurrences. Low-level events report actions by the user, changes in windows on the screen, and that the Event Manager has no other events to report

low-memory global variables

See: system global variables

low-order bit: The bit contributing the least value in a string of bits. For example, in the MC680x0 numbering scheme bit number 0 in a byte contributes a value of 20, or 1. Same as least significant bit

See also: high-order bit

LR

See: Link Register (LR)

luminance: The intensity of light in a color. Color QuickDraw uses a color's luminance to convert the color to an appropriate grayscale color.

luminance color space: A color space whose single component is the lightness or brightness of a color. Same as gray space.

luminance tint: A halftone tint type in which the tint color is specified by the luminance of the input color.

L*a*b* space: A nonlinear transformation (that is, a third-order approximation) of the Munsell color-notation system designed to match perceived color difference with quantitative distance in color space.

L*u*v* color space: A nonlinear transformation of XYZ space used to create a perceptually linear color space. This color space was designed to match perceived color difference with quantitative distance in color space.