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gadget. In AIXwindows, a windowless graphical object that looks like its equivalent like-named widget but does not support the translations, actions, or Popup widget children supplied by that widget.

gadget ID. In AIXwindows, a unique identification number assigned to each instance of a gadget used within a given graphical interface.

gamma correction. In GL, a logarithmic assignment of intensities to lookup table entries for shading applications. This is required since the human eye perceives intensities logarithmically rather than linearly. See also gamma ramp.

gamma ramp. In GL, a set of three lookup tables, one for each of the colors red, green, and blue, attached to the electron guns of the monitor. Entries in the gamma lookup table can be set to adjust for variations in the phosphor quality between different brands of monitors. Usually, a logarithmic curve is loaded into the gamma lookup tables. See also gamma correction. The gamma lookup tables are not a subset of the color map tables, but a separate entity.

gateway. (1.) An entity that operates above the link layer and translates, when required, the interface and protocol used by one network into those used by another distinct network. (2.) The network that connects hosts. See also active gateway. (3.) A device and its associated software that interconnect networks or systems of different architectures. The connection is usually made above the reference model network layer. For example, a gateway allows LANs access to System/390 host computers. Contrast with bridge.

gateway host. A host that connects independent networks. It has multiple interfaces, each with a different name and address.

Gateway-to-Gateway Protocol (GGP). The protocol with which a gateway determines connectivity to networks and neighbor gateways and implements the shortest-path routing algorithm.

gather. For input/output operations, to read data from noncontiguous memory locations to write to a device. Contrast with scatter.

GB. See gigabyte.

GC. See graphics context.

GC caching. In Enhanced X-Windows, allows independent change requests to be merged into one protocol request.

GContext. See graphics context.

GCP. Graphics Control Processor.

GCR. Group Code Recording, a magnetic tape recording format with a density of 6250 bpi.

GDA. Global Directory Agent.

GDLC. See generic data link control.

general purpose register (GPR). An explicitly addressable register that can be used for a variety of purposes (for example, as an accumulator or an index register). See also register.

generation. (1.) A means of referencing items in terms of time and ancestry so that an item without antecedents is designated as the first (n-th) generation and subsequent derivations are designated as n-1, n-2, and so on. (2.) For some remote systems, the translation of configuration into machine language.

generation number. A number used to differentiate between the uses of the same inode for several files or for different versions of the same file. When a file is created, an inode is allocated for the file, and a new generation number is stored in the inode for that file. Any use of an inode with the wrong generation number indicates that the user's view of the file is out-of-date, or "stale."

generation phase. The part of the sort program that translates the sequence specifications into machine language.

generic data link control (GDCL). A generic interface definition that provides application and kernel users a common set of commands to control DLC device managers within the operating system. Requirements for entry-point definitions, functions provided, and data structures for all DLC managers are specified. The following DLCs conform to this interface: IEEE 802.3 Ethernet, standard Ethernet, SDLC, and Token Ring.

generic interface. The interface, defined at a level that is independent of any particular programming language.

generic network. A Network Installation Management (NIM) network type used to define networks which are not currently known by NIM to support network boot operations.

generic unit. In Ada language, a template either for a set of subprograms or for a set of packages. A subprogram or package created using the template is called an instance of the generic unit. A generic instantiation is the kind of declaration that creates an instance. A generic unit is written as a subprogram or package but with the specification prefixed by a generic formal part which may declare generic formal parameters. A generic formal parameter is either a type, a subprogram, or an object. A generic unit is one of the kinds of program unit. See also instance.

geometric text. Text whose character fonts are defined by mathematical descriptions of the strokes required to draw the characters, rather than by raster images. Also called programmable character set or stroke text.

geometry. In Enhanced X-Windows, (1.) Window size and position on the screen. (2.) The size of a widget is changed using geometry management routines. Synonym for layout and geometry management.

geometry management. Synonymous with geometry.

GGP. See Gateway-to-Gateway Protocol.

ghost icon. An icon that indicates that a file is missing.

ghost instrument. In the Performance Toolbox, an empty space in the console where an instrument used to be, usually caused when a console designed for one system contains instruments not available on the current system. Ghost instruments occupy a space and prevent a new instrument from being defined in that same space or other instruments from being moved or resized to use the space.

ghosted. A description of an unavailable choice. Menu items are ghosted or "grayed out" to indicate that a standard choice is not available under the current circumstances.

GID. See group number.

gigabyte (GB). 1 073 741 824 in decimal notation when referring to memory capacity; in all other cases, it is defined as 1 000 000 000.

GL. Graphics Library.

GLB. See Global Location Broker.

glbd. The Global Location Broker daemon.

global. (1.) In programming languages, pertaining to the relationship between a language object and a block in which the language object has a scope extending beyond that block but contained within an encompassing block. (2.) Pertaining to information defined in one subdivision of a computer program and used in at least one other subdivision of the program. (3.) Pertaining to information available to more than one program or subroutine.

global area. (1.) A storage area used for communication between two or more main programs. (2.) An uninitialized portion of a partition accessible by any program of a task set in the partition at a given time. The same area may be used by other task sets that run in the same partition.

global character. The * and ? special characters that can be used in a file specification to match one or more characters. For example, placing ? in a file specification means any character can be in that position.

global data. Data that can be addressed by any process while in kernel mode, for example, tables, such as the open file table and process table, and other data maintained by the kernel, such as buffer pointers.

global forward substitution. An optimization in which the result of an assignment can be propagated forward through a program. For example, the assignment B=C followed by A=B can be replaced by A=C if B is not used elsewhere in the program.

Global Location Broker (GLB). Part of the NCS Location Broker. A server that maintains global information about objects on a network or an internet.

global variable. A symbol defined in one program module but used in other independently assembled program modules.

globbing. Synonym for file name substitution.

glossary window. A window that contains a glossary term.

glyph. (1.) An image, usually of a character, in a font. (2.) A graphic symbol whose appearance conveys information; for example, the vertical and horizontal arrows on cursor keys that indicate the directions in which they control cursor movement.

good citizenship. A group of standards established by the Inter-Client Communications Conventions Manual (ICCCM) that are supported and implemented by AIXwindows Window Manager. These standards prescribe behavior among clients in a multiclient environment to avoid costly compatibility problems.

goto statement. In programming languages, a statement that transfers control to another point in a program.

Gouraud shading. A method of shading polygons smoothly based on the intensities at their vertices. The color is uniformly interpolated along each edge, and then the edge values are uniformly interpolated along each scan line. For realistic shading, colors should be gamma corrected.

GPR. See general purpose register.

grab. (1.) The act of selecting keyboard keys, the keyboard, pointer buttons, the pointer, and the server for exclusive use by a client. In general, these facilities are not intended to be used by normal applications, but are intended for various input and window managers to implement various styles of user interfaces. See also active grab, passive grab, button grabbing, pointer grabbing, and key grabbing. (2.) A procedure by which a window acts upon a key or button event that occurs for it or any of its descendents. This precludes the necessity of setting up translations for all windows.

grab handles (or handles). In CDE, the small squares displayed at the corners and midpoints of a selected graphic element.

grammar rules. The structure rules in a parser program. See also parser.

granularity. The extent to which a larger entity is subdivided. For example, a yard broken into inches has finer granularity than a yard broken into feet.

graphic character. A character that can be displayed or printed.

graphical user interface. (1.) A boundary between two functional units that is displayed to the user by means of fundamental drawing units such as lines and polygons. (2.) A type of computer interface consisting of a visual metaphor of a real-world scene, often a desktop. Within that scene are icons, representing actual objects, that the user can access and manipulate with a pointing device. (Also called graphical interface.)

graphics. A type of data created from such fundamental drawing units such as lines, curves, polygons, and so forth.

graphics context (GC). In Enhanced X-Windows, the storage area for various kinds of graphics output, such as foreground pixel, background pixel, line width, and clipping region. Also known as "GC" and "GContext," a graphics context can be used only with drawables that have the same root and the same depth as the graphics context.

graphics pipeline. In GL, the sequence of steps that a graphics primitive goes through before it becomes visible on the screen: transformation from model coordinates to NDC coordinates; 3-D clipping (if out of bounds); perspective division; determination of color through lighting equations or depth-cueing; transformation of NDC coordinates to screen coordinates; 2-D clipping (by the screenmask); rasterization (drawing into the frame buffer); and display of frame buffer.

Graphics Support Library (XGSL). A two-dimensional graphics application programming interface to various output devices.

graPHIGS API. An implementation of PHIGS, based on the American National Standards Institute (ANSI) proposed standard, Programmer's Hierarchical Interactive Graphics System (PHIGS).

gravity. In Enhanced X-Windows, the contents of windows or subwindows have an attraction to a location within the window. This determines how the window ID is resized. See also bit gravity and window gravity.

gray scale. (1.) In Enhanced X-Windows, a type of degenerate pseudocolor where the red, green, and blue values in any given color map entry are equal, thus producing shades of gray. The gray values can be changed dynamically. (2.) Also GrayScale, a value. (3.) In a grayscale adapter, the different levels of intensity corresponding to the shades of gray produced. See also monochrome display.

grayed. A characteristic of a command or option that is listed on a menu or list box but cannot be chosen.

gross clipping. In GL, also known as 3-D clipping this is the clipping that occurs in normalized device coordinates, against the sides of the perspective frustum. All 3-D primitives undergo this clipping; in particular, the origin of text strings (but not individual letters) are clipped in this way. See also clipping, fine clipping, and clipping planes.

group. (1.) A collection of users who can share access authorities for protected resources. (2.) A list of names that are known together by a single name. (3.) A series of records logically joined together. (4.) A series of lines repeated consecutively as a set on a full-screen form or full-screen panel. (5.) A set of related records that have the same value for a particular field in all records.

Group Appointment. In CDE, in Calendar, an appointment for a group of people, scheduled using the Group Appointment Editor.

group ID (GID). A number that corresponds to a specific group name. The group ID can often be substituted in commands that take a group name as a value. Synonymous with group number.

group name. A name, which uniquely identifies a group of users to the system, that contains one to eight alphanumeric characters, beginning with an alphabetic, #, $, or > character.

group number. Synonym for group ID.

guard expressions. Expressions placed at the beginning of Boolean expressions to check that other operations can be done.

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