a

A

absolute colorimetric matching: A rendering intent that is used for a device-independent color space in which the result is an idealized print viewed on a perfect paper having a large dynamic range and color gamut. In reality, paper cannot reproduce densities less than a particular minimum density.

absolute position: A specific position, given in coordinates, for the origin of each character or glyph in the glyph shape

See also: relative position

absolute search: A search that begins at the root directory of the file system hierarchy and always descends the hierarchy

See also: relative search

abstract profile: A profile that allows applications to perform special color effects independent of the devices on which the effects are rendered

See also: profile, color space profile, device profile, named color space profile

abstract superclass: A superclass listed in the Apple Event Registry: Standard Suites, such as cObject or cOpenableObject, that is used only in definitions of object classes and not for real Apple event objects

See also: object class

Abstract Window Toolkit (AWT): In the Java runtime environment, a collection of functions that allows Java programs to manipulate virtual graphics (windows, images, buttons, and so on). These abstract graphics can be translated into user-visible windows and controls on the client platform

accelerated resource: An executable resource consisting of a routine descriptor and PowerPC code that specifically models the behavior of a 68K stand-alone code resource

See also: private resource

accelerated system software routine: Any Toolbox or Operating System routine that has been rewritten as PowerPC code.

accent colors: User-selectable fill colors for certain interface elements.

access controls: A set of bits that specify the types of operations a requestor is authorized to perform on a given catalog node, record, or attribute type.

access modes: A set of file permissions that specify what abilities should be allowed to a user attempting to open a file fork

See also: deny modes

access path: A description of the route that the File Manager follows to access a file; created when a file is opened

See also: file reference number

access permissions

See: access modes, file permissions

access privileges

See: directory access privileges

access rights: The permissions governing the access to a file, or the privileges governing the access to a directory.

action: One of many integer constants used by QuickTime movie controller components in the MCDoAction function. Applications that include action filters may receive any of these actions.

action button: A button that initiates the action associated with a dialog box; Save, Open, and Choose are common examples. The action button is often, but not always, the default button.

action procedure: A procedure that performs an action in response to the user holding the mouse button down while the cursor is in a control.

activate event: An event that indicates that a window is becoming active or inactive. Each activate event specifies the window to be changed and the direction of the change (that is, whether it's becoming active or becoming inactive).

activation procedure: An application-defined procedure that controls the highlighting of application-defined dialog items capable of receiving keyboard input.

active ADB device: The last ADB device to have sent data to the ADB Manager.

active application: The application currently interacting with the user. Its icon appears on the right side of the menu bar

See also: current process, foreground process

active control: A control in which the Control Manager responds to a user's actions by providing visual feedback"for example, by switching a button to its depressed state.

active field: The target of keyboard input in a dialog box.

active function: A function called by a scripting component periodically during script compilation and execution. You must provide an alternative active function for the use of scripting components if you want your application to get time during script compilation and execution for tasks such as spinning the cursor or checking for system-level errors.

active input area: In inline input, the area of the application window in which the user enters text for conversion by a text service component. The application and the text service component share responsibility for the active input area.

active movie segment: A portion of a QuickTime movie that is to be used for playback. By default, the active segment is set to the entire movie. You can change the active segment of a movie by using the Movie Toolbox.

active source rectangle: The portion of the maximum source rectangle that contains active video that can be digitized by a video digitizer component.

active window: The frontmost window on the desktop, generally the one in which the user is currently working.

activity timer: A timer maintained by the Power Manager that measures the time that has elapsed since the last relevant system activity.

ADB

See: Apple Desktop Bus (ADB)

ADB command: A 1-byte value sent by the ADB Manager to devices on the ADB. The ADB command encodes the register the command refers to and the desired action the target device should perform.

ADB device: Any input device connected to the ADB that conforms to requirements described in the Apple Desktop Bus Specification.

ADB device handler ID: An 8-bit value that further identifies a specific ADB device type (such as the Apple Extended Keyboard) or its mode of operation (such as whether the keyboard differentiates between the right and left shift keys).

ADB device register: One of four locations, identified as registers 0 through 3, that an ADB device uses to store data.

ADB device table: A structure, located in the system heap, that contains information about all ADB devices attached to the computer.

ADB device table entry: The part of the ADB device table that specifies for an ADB device its device handler ID, its default ADB address, its current ADB address, the address of its device handler, and the address of the area in RAM used for storage by the handler.

ADB Manager: The part of the Mac OS that allows you to communicate with and get information about hardware devices attached to the Apple Desktop Bus (ADB).

ADB transaction: A communication between the computer and an ADB device, consisting of a command sent by the computer, followed by a data packet sent either by the computer or the device.

additional parameter: A keyword-specified descriptor record that a server application uses in addition to the data specified in the direct parameter. For example, an Apple event for arithmetic operations may include additional parameters that specify operands in an equation. Additional parameters may be required, or they may be optional.

additive color theory: The process of mixing red, green, and blue lights, which are each approximately one-third of the visible spectrum. Additive color theory explains how red, green, and blue light can be added to make white light.

address: A number that specifies the location of a byte in memory.

address collision: When more than one ADB device responds to commands sent to a particular address

See also: address resolution

address descriptor record: A descriptor record of data type AEAddressDesc that contains the address of the target or source of an Apple event.

Address Management Unit (AMU): The Apple custom integrated circuit in Macintosh II computers that performs 24-bit to 32-bit address mapping.

address mapping: (1) The assignment of portions of the address space of the computer to specific devices. (2) See address translation.

address resolution: When the ADB Manager reassigns addresses for ADB devices until they are all unique

See also: default ADB device address

address space: A range of accessible memory

See also: address mapping

address template: A set of AOCE templates that allow a user to enter address information into a User record.

address translation: The conversion of one set of addresses into another, corresponding set. For example, software designed for the original Macintosh computers uses only 24 bits for addresses, whereas the Macintosh II and later models have a 32-bit address bus. As a result, the Macintosh II and later models convert (or map) the 24-bit addresses used by the software into the 32-bit addresses used by the hardware.

add mode: A transfer mode type in which the source color component is added to the destination component, but the result is not allowed to exceed the maximum value (0xFFFF).

ADSP

See: AppleTalk Data Stream Protocol (ADSP)

advance bits array: An array that determines whether the points in the positions array are absolute or relative. The advance bits array contains 1 bit for every character or glyph in the shape.

advance height: The distance from the top of a glyph to the bottom of the glyph, including the top-side bearing and bottom-side bearing.

advance width: The full horizontal width of a glyph as measured from its origin to the origin of the next glyph on the line, including the side bearings on both sides.

AEIMP

See: Apple Event Interprocess Messaging Protocol (AEIMP)

AEP

See: AppleTalk Echo Protocol (AEP)

AEP Echoer: The implementation of the AppleTalk Echo Protocol (AEP) on each node that uses the AEP Echoer or echoer socket; the AEP Echoer listens for packets received through this socket and sends a copy of them back to the sender. Applications use the AEP Echoer to measure the round-trip packet delivery time in analyzing network performance.

AE record: A descriptor record of data type AERecord that usually contains a list of parameters for an Apple event

See also: Apple event parameter

AFP

See: AppleTalk Filing Protocol (AFP)

AFP volume: A volume that is accessed using the AppleTalk Filing Protocol.

AGC

See: automatic gain control (AGC)

AIFF

See: Audio Interchange File Format (AIFF)

AIFF-C

See: Audio Interchange File Format Extension for Compression (AIFF-C)

alert: An alert sound, an alert box, or both. Alerts warn the user of an unusual or a potentially undesirable situation that is occurring

alert box: A window that an application displays on the screen to warn the user or to report an error to the user. An alert box typically consists of text describing the situation and buttons that require the user to acknowledge or rectify the problem. An alert box may or may not be accompanied by an alert sound

See also: caution alert, note alert, stop alert

alert color table resource: A resource (of type 'actb') that lets an application display an alert box using colors other than the system's default window colors.

alert notification: A notification in which an alert box containing a short message appears on the screen.

alert resource: A resource (of type 'ALRT') that specifies alert sounds, a display rectangle, and an item list for an alert box.

alert sound: An audible signal from the Macintosh speaker that warns the user of an unusual or a potentially undesirable situation occurring within an application. An alert sound may or may not be accompanied by an alert box.

Alert Sounds control panel: A subpanel of the Sound control panel that allows the user to select a system alert sound

See also: Sound In control panel, Sound Out control panel, Volumes control panel

alias: Data that refers to a file, directory, or volume. This data is typically stored in an alias handle.

aliasing: The result of sampling a signal at less than twice its natural frequency. Aliasing causes data to be lost in the conversion that occurs when resampling an existing signal at more than twice its natural frequency.

alias file: A file that contains a record that points to another file, directory, or volume. An alias file is displayed by the Finder as an alias.

Alias Manager: The part of the Operating System that helps you to locate specified files, directories, or volumes at a later time. The Alias Manager creates and resolves alias records.

alias record: A data structure created by the Alias Manager to identify a file, directory, or volume.

alias target: The file, directory, or volume described by an alias record.

alignment: (1) The horizontal placement of lines of text with respect to the left and right edges of the text area. Alignment can be left, right, centered, or justified (flush on both left and right edges)

allocate: To assign an area of memory for use.

allocation block: A group of consecutive logical blocks on a volume.

allophone: A distinct variety of a phoneme in a particular language that is never used contrastingly with any other allophone of the phoneme.

all object validation: A QuickDraw GX validation level that confirms that all references to all object types are valid, that the properties of the object are valid, and that all internal caches built for all objects are valid

See also: structure validation, type validation

alphabet: The set of letters, or characters, used to write a language. The alphabet used by the Roman script consists of 26 letters.

alphabetic writing system: The glyphs that symbolize discrete phonemic elements in a language

See also: ideographic writing system, syllabic writing system

alpha channel: (1) The portion of each display pixel that represents the blending of video and graphical image data for a video digitizer component. (2) A color component in some color spaces whose value represents the opacity of the color defined in the other components.

alpha-channel transfer modes: Transfer mode types in which the result color is achieved by considering the alpha channel values as well as the color-component values of the source and destination.

alternate group: A collection of movie tracks that contain alternate data for one another. The Movie Toolbox chooses one track from the group to be used when the movie is played. The choice may be based on such considerations as quality or language.

alternate interface: The first version of the AppleTalk Pascal interfaces. The alternate interface was replaced with the current version of AppleTalk Pascal interfaces, which was originally referred to as the preferred interface.

alternate rectangle: A rectangle used by the Help Manager (under some circumstances) for transposing a help balloon's tip when trying to fit the balloon onscreen. For all help resources except the 'hdlg' resource, the Help Manager moves the tip to different sides of the hot rectangle. For 'hdlg' resources, however, the Help Manager allows you to specify alternate rectangles for transposing balloon tips. You can also specify alternate rectangles when you use the HMShowBalloon and HMShowMenuBalloon functions

See also: hot rectangle, tip

AMP

See: asymmetric multiprocessor (AMP)

amplitude: A modification to the wave amplitude of a sound to make it sound louder or softer

See also: speech volume, wave amplitude

AMU

See: Address Management Unit (AMU)

AND mode: A transfer mode type in which the bits of the source color component and destination color component are combined using an AND operation.

angle: The angle from horizontal made by the pattern of dots in a halftone.

angled caret: A caret whose angle in relation to the baseline of the display text is equivalent to the slant of the glyphs making up the text

See also: straight caret

animated color: A color that the Palette Manager uses for special animation effects. Animated colors work only on devices that have a color table; that is, they do not work on direct devices.

ANSI C language dialect: The C programming language dialect that adheres to the language defined by the document American National Standard for Information Systems -- Programming Language -- C, ANSI X3.159-1989.

ANSI X3J11.1: A branch of the American National Standards Institute (ANSI) that is working on a numerics standard for the C programming language. This group is also called the Numerical C Extensions Group (NCEG) and has produced the Floating-Point C Extensions (FPCE) technical report.

antisymmetric: Used to describe a function whose graph is not symmetrical across the y-axis; that is func(x) _ func(_x) for all x.

anti-aliasing: (1) The process of sampling a signal at more than twice its natural frequency to ensure that aliasing artifacts do not occur. (2) The smoothing of jagged edges on a displayed shape by modifying the transparencies of individual pixels along the shape's edge.

AOCE: Apple Open Collaboration Environment.

AOCE catalog: A hierarchically arranged store of data in a format intelligible to the AOCE Catalog Manager

See also: external catalog, PowerShare catalog

AOCE messaging system: The set of PowerTalk system software and PowerShare mail servers that allows Macintosh users and processes connected over a network or via a modem to exchange information.

AOCE Setup catalog

See: PowerTalk Setup catalog

AOCE system software: The collection of Mac OS managers and utility functions that provide APIs for catalog, messaging, and security services. The AOCE system software includes the Standard Mail Package, the Standard Catalog Package, AOCE templates, the Interprogram Messaging Manager, the Catalog Manager, the Authentication Manager, and the Digital Signature Manager, as well as utility functions

See also: PowerTalk system software

AOCE template: A resource file that extends the AOCE extension to the Finder to display new types of data in catalogs or to display data in a new way

See also: aspect template, file type template, forwarder template, information page template, killer template

AOCE toolbox: The low-level APIs for the AOCE system software: the Authentication Manager, Catalog Manager, Interprogram Messaging Manager, and Digital Signature Manager

See also: Collaboration package, Collaboration toolbox

API

See: application programming interface (API)

appearance: A coordinated set of visual designs that determine the look of human interface objects on a systemwide basis

See also: theme

Appearance Manager: The part of the Mac OS that manages all aspects of appearances and themes, including support for animation, sound, and a variety of color data

See also: appearance, theme

AppleMail format

See: standard interchange format

AppleScript component: The scripting component that implements the AppleScript scripting language

See also: scripting component

AppleScript scripting language: The standard user scripting language defined by Apple Computer, Inc. The AppleScript scripting language is implemented by the AppleScript scripting component

See also: dialect

applet: In the Java runtime environment, an executable program that must run within a larger host application. In JManager, an instantiated applet is called a JMAppletViewerRef object.

AppleTalk connection file: A file of type 'adev' that contains a link-access protocol implementation for a data link (ELAP for EtherTalk, for example).

AppleTalk Data Stream Protocol (ADSP): A connection-oriented protocol that provides a reliable, full-duplex, byte-stream service between any two sockets in an AppleTalk internet. This protocol appears to its clients to maintain an open pipeline between two entities on an AppleTalk internet. Either entity can write a stream of bytes to the pipeline or read data bytes from the pipeline. ADSP is a symmetrical protocol.

AppleTalk Echo Protocol (AEP): A simple protocol that allows a node to send a packet to the echoer socket of any other node in an AppleTalk internet and receive an echoed copy of that packet in return. AEP is implemented in each node as a DDP client process that is referred to as the AEP Echoer.

AppleTalk Filing Protocol (AFP): A protocol that allows users to share data files and application programs that reside in a shared file server.

AppleTalk internet: A type of network in which more than one AppleTalk network are interconnected through routers. An AppleTalk internet can consist of a mix of LocalTalk, TokenTalk, EtherTalk, and FDDITalk networks, or it can consist of more than one network of a single type, such as several LocalTalk networks.

AppleTalk Manager: A collection of the application programming interfaces to the AppleTalk protocols.

AppleTalk multivendor architecture

See: multivendor architecture

AppleTalk protocol stack: The AppleTalk networking system, which consists of a number of protocols arranged in layers.

AppleTalk Secure Data Stream Protocol (ASDSP): A networking protocol that provides reliable transmission of an encrypted stream of bytes between two authenticated entities on an AppleTalk internet. ASDSP is a secure version of AppleTalk Data Stream Protocol (ADSP).

AppleTalk Session Protocol (ASP): A protocol that provides asymmetric session support. It uses the services of ATP to establish, maintain, and break down the session.

AppleTalk Transaction Protocol (ATP): A transport protocol that provides a loss-free transaction service between sockets. ATP allows for the exchange of a limited amount of data in which a client requester application sends a request to a client responder application that can satisfy the request and respond to it. Because it is transaction-based, ATP does not incur the overhead entailed in establishing, maintaining, and breaking a connection that is associated with connection-oriented protocols, such as ADSP. ATP provides reliable delivery of data.

AppleTalk transition: A change in AppleTalk's current state or function, such as an AppleTalk driver being opened or closed or a network connection or link being dropped, that can affect active AppleTalk applications.

AppleTalk Transition Queue (ATQ): An operating-system queue that the LAP Manager maintains that can notify an application each time an AppleTalk driver is opened or closed or each time certain other network-related transitions occur.

applet tag: Text in an HTML document that describes an embedded applet. This text is bounded by the < APPLET > and < /APPLET > delimiters

See also: Hypertext Markup Language (HTML)

Apple Class Suites (ACS): A set of object-oriented classes, written primarily in C++, that provides a wide variety of features, some of which were formerly implemented as part of the MacApp library. The ACS is independent of MacApp, but MacApp relies on the ACS.

Apple Desktop Bus (ADB): A low-speed serial bus that connects input hardware devices to Macintosh computers and other equipment.

Apple event: A high-level event that adheres to the Apple Event Interprocess Messaging Protocol. An Apple event consists of attributes (including the event class and event ID, which identify the event and its task) and, usually, parameters (which contain data used by the target application for the event)

See also: Apple event attribute, Apple event parameter

Apple event array: An array in a descriptor list. The data for an Apple event array is specified by an array data record, which is defined by the data type AEArrayData.

Apple event attribute: A keyword-specified descriptor record that identifies the event class, event ID, target application, or some other characteristic of an Apple event. Taken together, the attributes of an Apple event identify the event and denote the task to be performed on the data specified in the Apple event's parameters. Unlike Apple event parameters (which contain data used only by the target application of the Apple event), Apple event attributes contain information that can be used by both the Apple Event Manager and the target application

See also: Apple event parameter

Apple event dispatch table: A table in either the application heap or the system heap that the Apple Event Manager uses to map Apple events to the appropriate Apple event handlers.

Apple event handler: An application-defined function that extracts pertinent data from an Apple event, performs the action requested by the Apple event, and returns a result.

Apple Event Interprocess Messaging Protocol (AEIMP): A standard defined by Apple Computer, Inc., for communication and data sharing among applications. High-level events that adhere to this protocol are called Apple events

See also: Apple event

Apple Event Manager: The collection of routines that allows client applications to send Apple events to server applications for the purpose of requesting services or information.

Apple event object: A distinct item in a target application or any of its documents that can be specified by an object specifier record in an Apple event sent by a source application. Apple event objects can be anything that an application can locate on the basis of such a description, including items that a user can differentiate and manipulate while using an application, such as words, paragraphs, shapes, windows, or style formats

See also: object specifier record

Apple event object class

See: object class

Apple event parameter: A keyword-specified descriptor record containing data that the target application for an Apple event uses. Unlike Apple event attributes (which contain information that can be used by both the Apple Event Manager and the target application), Apple event parameters contain data used only by the target application of the Apple event

See also: Apple event attribute, direct parameter, optional parameter, required parameter

Apple event record: A descriptor record of data type AppleEvent that contains a list of keyword-specified descriptor records. These descriptor records describe"at least"the attributes necessary for an Apple event; they may also describe parameters for the Apple event. Apple Event Manager functions are used to add parameters to an Apple event record.

Apple event user terminology resources: Two resources with identical formats used by server applications to specify the Apple events and corresponding user terminology that the applications support. The 'aeut' resource, which is provided by scripting components, contains terminology information for all the standard suites of Apple events defined in the Apple Event Registry: Standard Suites. An 'aete' resource must be provided by every scriptable application; it describes which of the standard suites listed in the 'aeut' resource the application supports and provides additional terminology information for extensions to the standard suites and custom Apple events supported by the application

See also: scripting component

Apple Menu Items folder: A directory located in the System Folder for storing desk accessories, applications, folders, and aliases that the user wants to display in and access from the Apple menu.

Apple Mixer

See: Apple Mixer component

Apple Mixer component: A sound component that is responsible for mixing together the audio data streams from all open sound channels.

Apple Sound Chip (ASC): A custom chip that, in conjunction with other circuitry, generates a stereo sound signal that drives the internal speaker or an external sound jack

application: A program of type 'APPL' that is launched from the Finder. Applications typically use event-driven programming and have a user-interface

See also: program

application extension: A fragment containing code and data (such as a data-conversion filter, tool, and so forth) that extends the capabilities of an application.

application font: The default font for use by applications. The application font is defined by each script system.

application global variables: A set of variables stored in the application partition that are global to the application.

application heap: (1) An area of memory in the application heap zone in which memory is dynamically allocated and released on demand. The heap contains the application's 'CODE' segment 1, data structures, resource map, and other code segments as needed. (2) The part of computer memory directly accessible by an application, and in which its code and data structures reside

See also: graphics client heap, QuickDraw GX memory

application heap zone: The heap zone initially provided by the Memory Manager for use by an application and the Toolbox; initially equivalent to the application heap, but may be subdivided into two or more independent heap zones.

application memory

See: application heap

application parameters: Thirty-two bytes of memory in the A5 world of a 680x0 application that are reserved for system use. The first long word is the address of the first QuickDraw global variable.

application partition: A partition of memory reserved for use by an application. The application partition consists of free space, along with the application's heap and stack. The application partition for a 680x0 application also contains an A5 world.

application phase: In QuickDraw GX printing, the phase when the application calls QuickDraw GX and interacts with the user by displaying dialog boxes to establish printing parameters, such as page orientation and paper type.

application programming interface (API): The total set of constants, data structures, routines, and other programming elements that allow developers to use some part of the system software

application result handler: A result handler that is associated with a particular application

See also: system result handler

application space: Memory that's reserved for dynamic allocation by applications.

application transition vector: A 12-byte transition vector used in the CFM-68K runtime environment. The first two fields contain the address of a function and the value to be placed in A5 when the function executes. Because applications can be segmented, the third field contains information to locate the function within a particular segment

See also: shared library transition vector, transition vector

application translation extension: A translation extension that can create a list of file types and identify files but that performs no actual file translation.

application-owned dialog box: A dialog box, created by an application, for presenting a color picker.

approval file: A file you receive from a signature-authorization-issuing agency. You use this file to activate your signer file.

approval request: A notarized (or otherwise authorized) request to issue a public-key certificate. The approval request includes what is intended to be the public key of the certificate's owner.

approved signer file

See: signer file

approving agency

See: certificate issuer

Arabic calendar: A lunar calendar used in much of the Arabic world. There are two Arabic calendars supported by the Arabic script system: the astronomical lunar calendar, based on the moon's phases as actually observed at each location around the world; and the civil lunar calendar, a statutory version of the astronomical calendar. In both versions, the positions in time of each month vary from year to year.

Arabic numerals: In the Macintosh script management system, numerals native to the Arabic writing system and not used in the Roman writing system

See also: western numerals

arbitrated CMM: A CMM selected by the ColorSync Manager from the available source and destination profiles to perform a specified operation

See also: preferred CMM

arbitration phase: The phase in which an initiator attempts to gain control of the SCSI bus.

arc: A portion of the circumference of an oval, not including the bounding radii or any part of the oval's interior.

area of interest: The portion of a test image that is to be displayed in the standard image-compression dialog box.

arithmetic transfer mode: (1) A specification for how QuickDraw should draw or copy color images into a bitmap or pixel map. Arithmetic modes perform add, subtract, and blend operations on the red, green, and blue component values of RGB colors. (2) Transfer mode types in which the result color is achieved by using arithmetic operations on the source and destination color-component values.

ASC

See: Apple Sound Chip (ASC)

ascent line: An imaginary horizontal line that coincides with the tops of the tallest characters in a font

See also: baseline, descent line, x-height

ASCII character set: The standard set of Roman characters, with character-code values from $00 to $7F. Also called low ASCII, to distinguish them from character codes with values from $80 to $FF, which are sometimes called high ASCII or extended ASCII. The Roman characters that are part of each non-Roman character set are the low ASCII set only

See also: Macintosh character set, Standard Roman character set

ASDSP

See: AppleTalk Secure Data Stream Protocol (ASDSP)

ASP

See: AppleTalk Session Protocol (ASP)

aspect: A structure in memory that contains properties provided by an aspect template. An aspect might also contain code provided by the code resource in an aspect template.

aspect template: An AOCE template that specifies how attributes in a record are to be parsed into properties for display in an information page. An aspect template can also specify certain constant property values and can contain a code resource that translates between property types and implements features in information pages

See also: information page template

associated font: A Roman font whose glyphs are automatically substituted for glyphs of a non-Roman font, for characters in the Roman range. For example, the Arabic script system uses an associated font to display all Roman characters, even within script runs of Arabic text.

asymmetrical session: A session in which only one end of the connection can control the communication. One end of the connection makes a request to which the other end can only respond.

asymmetric multiprocessor (AMP): Having more than one processor execute instructions so that one processor, the master processor, executes all operating system_related operations. Other processors, called slave processors, perform operations allocated to them by the master processor

asynchronous arrow: A control which indicates through a simple animation that a background process is in progress

See also: progress indicator

asynchronous communication: A method of data transmission in which the receiving and sending devices don't share a common timer and no timing data is transmitted.

asynchronous device driver: A device driver that can begin processing a request and return control to the Device Manager before the request is complete. This type of driver typically uses hardware interrupts and callback routines to carry out background processing.

asynchronous execution: A mode of executing a routine in which the system returns control to the calling program directly after the program calls the routine so that the calling program can continue with other processing while the routine is either queued for execution or completes execution

See also: completion routine

asynchronous I/O operation: An operation that performs data input or output while the program requesting the operation remains eligible for execution

asynchronous parameter block: In the Data Access Manager, the parameter block that allows a routine to return control to your application before the routine has completed execution.

asynchronous sound play: The playing of sound during other, non-sound related operations

See also: synchronous sound play

atom: The basic unit of data in a movie resource. There are a number of different atom types, including movie atoms, track atoms, and media atoms. There are two varieties of atoms: container atoms, which contain other atoms, and leaf atoms, which do not contain any other atoms.

atomic operations: Operations that pass extra information back to their callers by signaling exceptions but that hide internal exceptions, which might be irrelevant or misleading.

atop mode: A transfer mode type in which the source color is placed over the destination, but the resulting destination retains the original destination's transparency.

ATP

See: AppleTalk Transaction Protocol (ATP)

ATP sequence number: The bitmap/sequence number field of the header, when the ATP packet is a response packet. The ATP sequence number is used to identify the sequential position of the response packet in the complete response message; ATP uses the sequence number to manage and handle lost or out-of-sequence response packets.

ATQ

See: AppleTalk Transition Queue (ATQ)

attached controller: A movie controller with an attached movie.

attribute: The smallest unit of data in an AOCE catalog; the data within a record is organized into attributes. Each attribute has a type indicating the type of data, a tag indicating the format of the data, a creation ID, and data (the attribute value).

attributes: A property of many QuickDraw GX objects. The attributes property of an object is a set of flags that control various aspects of that object's behavior.

attribute creation ID: A number assigned by a catalog that uniquely identifies an attribute value within a record. It persists for as long as the attribute value exists and is never reused. Not all catalogs support attribute creation IDs

See also: pseudo-persistent attribute creation ID

attribute mask: A means of editing the attributes of a collection.

attribute tag

See: attribute value tag

attribute type: (1) An integer constant describing a data attribute of a dictionary entry. (2) The type of data in an attribute; for example, telephone number or picture. A record can contain more than one attribute type, and there can be more than one attribute value of the same attribute type in a record.

attribute value: The data in an attribute.

attribute value tag: The format of the data in an attribute value.

at-least-once transaction: A type of ATP transaction that ensures that the responder application receives every request directed to it at least once. This type of ATP transaction allows for the possibility of a responder application receiving duplicate requests

See also: exactly-once (XO) transaction

audible notification: A notification in which the Sound Manager plays the system alert sound or a sound contained in an 'snd ' resource.

audio component: A component that works with the Sound Manager to adjust volumes or other settings of a sound output device

See also: sound component

audio compression: A technique of reducing the amount of memory space required for a buffer of sampled-sound data, usually at the expense of audio fidelity

See also: audio expansion

audio data

See: sampled-sound data, sound, square-wave data, wave-table data

audio decompression

See: audio expansion

audio expansion: The decompression of compressed sound data

See also: audio compression

audio information record: A structure you can use to specify information about an audio component. Defined by the AudioInfo data type.

Audio Interchange File Format Extension for Compression (AIFF-C): An extension of the Audio Interchange File Format that allows for the storage of compressed sound data.

Audio Interchange File Format (AIFF): A sound storage file format designed to allow easy exchange of audio data among applications.

audio port: Any independently-controllable sound-producing hardware connected or attached to a sound output device. A sound output device can have several audio ports.

audio selection record: A structure you can use to specify that only part of a sound be played. Defined by the AudioSelection data type.

authentication: The process of establishing the identit y of an entity on a network or of one end of a communication link. The authentication mechanism of the PPC Toolbox identifies each user through an assigned name and password.

authentication identity

See: identity

Authentication Manager: The part of the Mac OS that authenticates users of AOCE messaging and catalog services and provides authentication services to applications.

authentication process: A process that ASDSP performs to positively identify two parties who want to communicate over a secure ADSP connection. The process, which is a kind of handshake, involves the use of a session key.

authentication server: A secure network-based server that holds the client keys of users and services and generates credentials that allow users to do mutual authentication.

automatic form substitution: The process of automatically substituting one or more glyphs for one or more other glyphs.

automatic gain control (AGC): A feature of sound recording that moderates the recording to give a consistent signal level.

automatic key frame: A key frame that is inserted automatically by the Image Compression Manager when it detects a scene change. When performing temporal compression, the Image Compression Manager looks for frames that have changed more than 90 percent since the previous frame. If such a change occurs, the Image Compression Manager assumes a scene change and inserts a key frame. A key frame allows fast random access and reverse play in addition to efficient compression and picture quality of the frame.

autosense: A feature of SCSI Manager 4.3 that automatically sends a REQUEST SENSE command in response to a CHECK CONDITION status, and retrieves the sense data.

auto-key event: An event indicating that a key is still down after a certain amount of time has elapsed.

auto-key rate: The rate at which a character key repeats after it's begun to do so.

auto-key threshold: The length of time a character key must be held down before it begins to repeat.

auto-pop bit: Bit 10 of a Toolbox trap word, signifying that an extra return address is placed on the stack.

auxiliary script: A script system other than the system script that is available for application use. An auxiliary script can be used in documents, but it does not affect the default behavior of the system software.

auxiliary window structure: A data structure that the Window Manager uses to tie together a list of windows and their corresponding window color information tables.

AWT context: An instantiation of an execution environment in the Java runtime environment. An AWT context is a separate thread and may represent a thread group. An AWT context typically contains an applet and one or more frames. In JManager, an AWT context is called a JMAWTContextRef object

See also: Abstract Window Toolkit (AWT)

A5 world: In classic 68K and CFM-68K runtime programs, a memory partition that contains the QuickDraw global variables, the application global variables, the application parameters, and the jump table"all of which are accessed through the A5 register. Sometimes called the global variable world

See also: mini-A5 world

A-line instruction: An instruction used to execute Toolbox and Operating System routines. The first word of an A-line instruction is binary 1010 (hexadecimal A). Also known informally as an A-trap.

A-trap

See: A-line instruction

'adev' file

See: AppleTalk connection file