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race condition. For the signal subroutine, the condition in which the signal occurs while the signal action is set to the SIG_DFL value, and the signal-catching function has not yet established itself as the catcher for this signal.

radio box. Special configuration of toggle buttons within a row column manager widget.

radio button. Indicates a fixed set of choices. Only one of the buttons in the set can be selected at a time. A circle with text alongside, the circle is partially filled when a choice is selected.

radio frequency interference. A signal (noise) that is radiated or conducted from one electronic circuit or device the may cause incorrect operation interference in another electronic circuit or device. An electronic circuit or device can be an emitter of electromagnetic interference (EMI) or susceptible to electromagnetic interference.

raise. To make the stacking order of a window higher.

raising an exception. For Ada programming, see exception.

RAM. Random access memory. Specifically, the memory used for system memory. Sometimes this memory is referred to as main storage.

random access. An access mode in which records can be read from, written to, or removed from a file in any order.

random file access. Location of a record that matches a specific index key value. Random access of the records in a file requires that the file have a unique index and that each record have a unique index key value.

range. In Ada language, a contiguous set of values of a scalar type. A range is specified by giving the lower and upper bounds for the values. A value in the range is said to belong to the range.

range constraint. In Ada language, a range constraint of a type specifies a range, and thereby determines the subset of the values of the type that belong to the range.

range of a DO loop. Those statements that physically follow a DO statement, up to and including the final statement specified by the DO statement.

range of records. Multiple records to be processed sequentially. A range of records is selected by specifying key values that bound the records to be selected, or by specifying an individual key value for which all matching records should be selected in a nonunique index.

raster. The area of the video display that is covered by sweeping the electron beam of the display horizontally and vertically. Normally the electronics of the display sweep each line horizontally from top to bottom and return to the top during the vertical retrace interval. See also frame buffer.

raster font. A font in which the characters are defined directly by the raster bit map. See also font and primitive font.

raster graphics. Computer graphics in which a display image is composed of an array of pixels arranged in rows and columns.

raster mosaics. An area in annotated text fonts that contains a definition for each character in the font.

raster subsystem. That part of the system concerned with an image after it has been transformed and scaled to screen coordinates. It includes scan conversion and display.

raw device. A device that treats data I/O as a continuous stream, without consideration for the data's logical structure. For example, I/O for fixed disks and streaming tapes occurs in units of bytes that have no relationship to characters.

raw I/O. Character-oriented access to a block device not utilizing in-core buffers.

raw tape device. See raw device.

RC. Routing control.

RCM. (1) See real-time control microcode. (2) Rendering Context Manager.

RCS. See Revision Control System.

RD. Receive Data used with EIA-232 protocol.

read access. An access right that grants the ability to view CDS data.

read-only file. Pertaining to file system mounting, a condition that allows data to be read but not copied, printed, or modified.

Read Only Storage (ROS) menus. The menus displayed by system ROS on a target. Information used in booting the target is provided by the user to the ROS menus.

read queue. A message queue in a module or driver containing messages moving upstream. Associated with input from a driver.

readers and writers. In the SOM Replication Framework, different processes can access the same replicated object in different modes. A "reader" is a process that does not intend to update the object, but wants to continually watch the object as other processes update it. A "writer" is a process that wants to update the object, as well as continually watch the updates performed by others.

real constant. A string of decimal digits that expresses a real number. A real constant must contain either a decimal point, a decimal exponent, or both.

real device. The actual device hardware.

real group ID. For each user, the group ID defined in the password file.

real memory. The active physical memory on any system. Contrast with virtual memory.

real number. (1.) A number that contains a decimal point and is stored in fixed-point or floating-point format. (2.) A number that can be represented by a finite or infinite numeral in a fixed-radix numeration system.

real operation. Any operation on Ada floating-point or fixed-point values.

real page number. This field in the translation control word (TWC) contains the real page address that the bus address is mapped to in system memory.

real storage. Storage directly accessible to the processor from which instructions can be run and from which instructions can fetch data.

real time. (1.) The time elapsed between the loading of a program and its completion. (2.) Pertaining to the processing of data by a computer in connection with another process outside the computer, according to time requirements imposed by the outside process. (3.) Used to describe systems that operate in conversational mode and processes that can be influenced by human intervention while in progress. (4.) Pertaining to an application, such as a process control system or a computer-assisted instruction system, in which response to input is fast enough to affect subsequent input.

real-time control microcode (RCM). In X.25 communications, the microcode that runs on the X.25 Interface Co-Processor/2 to provide control functions.

real-time system. A system that receives and processes data so the data or result is available for immediate use.

real type. (1.) An arithmetic data type that can approximate the values of real numbers. (2.) In Ada language, a real type is a type whose values represent approximations to the real numbers. There are two kinds of real type: fixed point types are specified by absolute error bound; floating point types are specified by a relative error bound expressed as a number of significant decimal digits.

real user ID. (1.) Identifies the user who was authenticated the last time the login command or su command was used. (2.) For each user, the user ID that is specified in the /etc/passwd file.

realm. A cell, considered exclusively from the point of view of security; this term is used in Kerberos specifications.

rebinding. Reestablishing a communications channel for making remote procedure calls after that channel has been closed.

reboot. To reinitialize the execution of a program by repeating the initial program load (IPL) operation.

REC. See Lock Service.

receive. In X.25 communications, to take an incoming packet (such as an incoming-call packet or a data packet) from the buffer.

receive pacing. In SNA, the pacing of message units that a component is receiving. Contrast with send pacing. See also pacing.

receive time out. In data communications, a condition that occurs when no data is received in a given period of time.

recognized private operating agency (RPOA). A private X.25 network that can optionally be selected by the user at call setup time to carry the X.25 traffic.

Recommendation X.25. See X.25.

record. (1.) In programming languages, an aggregate that consists of data objects, possibly with different attributes, that usually have identifiers attached to them. (2.) A set of data treated as a unit. (3.) A collection of fields treated as a unit. See also class record, widget record, and instance record.

record lock. A lock that prevents some or all of a file from being written to or read. See also lock.

record name. A data name for a record described in a record description entry.

record type. (1.) The classification of records in a file. (2.) In Ada language, a value of a record type consists of components are usually of different types or subtypes. For each component of a record value or record object, the definition of the record type specifies an identifier that uniquely determines the component within the record.

recording instrument. In Performance Toolbox, an instrument with the ability to show the statistics for a system resource over a period of time. Recording instruments typically have a time scale with the current time to the right. The values plotted are moved to the left as new readings are received. Types of graphs used to plot these recordings include line, area, skyline, and bar graphs. Contrast with state instrument.

recoverable data. Data whose values persist across system shutdowns and failures. Changes made to recoverable data are permanent regardless of system problems. Logging changes to recoverable data is the most common method used to ensure permanence. The changes to that data recorded in the log can always be replayed to bring that data to a valid state.

recovery procedure. (1.) An action performed by the operator when an error message appears on the display screen. This action usually permits the program to continue or permits the operator to run the next job. (2.) The method of returning the system to the point where a major system error occurred and running the recent critical jobs again. (3.) A process in which a specified data station attempts to resolve conflicting erroneous conditions arising during the transfer of data.

rectangle. A rectangle specified by [x,y,w,h] has an infinitely thin outline path with corners at [x,y][x+w,y][x+w,y+h] and [x,y+h]. In XGSL,when a rectangle is filled, the lower-right edges are not drawn. For example, if w=h=0, nothing would be drawn; if w=h=1, a single pixel would be drawn.

recurring attribute. An attribute with several attribute values.

recursion. (1.) Using a function to define itself. (2.) Performing an operation in several steps, with each step using the output of the preceding step.

redirect. To divert data from a process to a file or device to which it would not normally go.

redirecting control. Transferring an operation to a specified client. Used when window managers or client programs enforce window layout policy to prevent attempts to change the size or position of a window.

redispatch stub. In SOM, a procedure, corresponding to a particular method, which has the same signature as the method's procedure but which invokes somDispatch to dispatch the method. The somOverrideMtab method can be used to replace the procedure pointers in a class's method table with the corresponding redispatch stubs. This is done when overriding somDispatch to customize method resolution so that all static methodinvocations will be routed through somDispatch for selection of an appropriate method procedure. (Dynamic methods have no entries in the method table, so they cannot be supported with redispatch functionality.)

Reduced Instruction Set Computer (RISC). A class of computer designs that uses a relatively small set of frequently used instructions that execute in one cycle.

reentrant service. A service that is safe to call from multiple threads in parallel. If a service is reentrant, there is no burden placed on calling routines to serialize their access or take other explicit precautions. See also thread-serial service, and thread-synchronous service.

refer. A bibliographic preprocessor for the nroff and troff commands. "Refer" is designed for literature citations, and it supports data entry, indexing, sorting, retrieval, printing, citations, and either footnote or endnote numbering.

reference bit. A bit in each page frame table entry that denotes that the corresponding page has been accessed (either read from or written to) since the last time the operating system cleared the page.

reference count. In an i-node, a record of the total number of directory entries that refer to the i-node.

reference data. In SOM, application-specific data that a server uses to identify or describe an object in DSOM. The data, represented by a sequence of up to 1024 bytes, is registered with DSOM when a server creates an object reference. A server can later ask DSOM to return the reference data associated with an object reference. See also object reference.

reference monitor. Code that controls access to an object.

reference widget. The parent widget that searched for children satisfied the search criteria.

refresh rate. The rate at which the monitor is refreshed. A 60 Hz monitor is redrawn 60 times per second. Synonymous with vertical retrace.

region. An area within a bitmap, a pixmap, a screen, or a window.

Region. An arbitrary set of pixel locations. The Xlib library provides subroutines for manipulating regions. The opaque type Region is defined in the <X11/Xutil.h> header file.

register. (1.) A storage device having a specified storage capacity such as a bit, byte, or computer word, and that is usually intended for a special purpose. See also general purpose register. (2.) In NCS, to make an interface known to the RPC run time library and, thereby, available to clients through the RPC mechanism. The rpc_$register call registers an interface. (3.) In NCS, to enter an object and its location in the Location Broker database. The lb_$register call registers an object with the Location Broker. A program can use Location Broker lookup calls to determine the location of a registered object.

registration. The creation of an object in the network installation database that uniquely identifies a client, network, or resource in the network installation environment to the master server.

Registry database. A database of information about persons, groups, organizations, and accounts.

regular expression. (1.) A set of characters, meta characters, and operators that define a string or group of strings in a search pattern. (2.) A string containing wildcard characters and operations that define a set of one or more possible strings. Contrast with literal string. See also collating element and subpattern.

reject. To cause portions of applied updates from becoming permanent parts of the product, based on the results of a test period. When you reject an applied service update, the update's files are deleted and the software vital product data (SWVPD) information is changed to indicate that the update is no longer on the system. The previous version of the software, if there is one, is restored and becomes the active version of the software. Contrast with apply and commit.

relational expression. (1.) A logical statement that describes the relationship (such as greater than or equal) of two arithmetic expressions or data items. (2.) An expression that consists of an arithmetic expression followed by a relational operator, followed by another arithmetic expression, and that can be reduced to a value that is true or false.

relational operator. (1.) The reserved words or symbols used to express a relational condition or a relational expression. (2.) An operator that compares two operands and yields a Boolean value.

relational transformation. A transformation that changes an arithmetic relational expression into the negation of its logical complement. For example, a relational transformation of A>B is NOT(A<=B).

relative address. (1.) An address specified relative to a base address. (2.) An address counted relative to a symbol. When a program is relocated, the addresses themselves change, but the relative addresses remain the same.

relative directory. A directory whose name begins with a ./ (dot and a slash).

Relative Distinguished Name (RDN). A set of Attribute Value Assertions (AVAs), each of which is true, concerning the distinguished values of a particular entry.

relative drawing commands. In computer graphics, commands that draw relative to the current graphics position as opposed to being drawn at absolute locations.

relative file. A file organized as an array of fixed-length slots. Records can be inserted in the first free slot found from the beginning or end of the file, or can be explicitly positioned in a certain slot in the file, identified by its relative slot number (RSN).

relative path name. The name of a directory or file expressed as a sequence of directories followed by a file name, beginning from the current directory. Relative path names do not begin with a / (slash) but are relative to the current directory. See also path name and full path name.

relative record number. A number that expresses the location of a record in relation to a base position in the file containing it.

relative slot number (RSN). The number of the slot occupied by a record in a relative file. The RSN is part of the user's data record. Each record in a relative file contains a field that holds its RSN.

relative time. A discrete time interval that is usually added to or subtracted from an absolute time.

release number. The release level of a program, which is an indicator of changes to the external programming interface of the program. The version, release, modification, and fix levels together comprise the program level or version of a program. See also fix number, modification number, version number, program level and version.

release update package. A set of selective enhancements, filesets, and new versions of optional software products available since the last release of the operating system. Also included is a maintenance level package for each software package.

reliable stream delivery. A type of packet delivery that allows an application program on one machine to connect to an application program on another machine. The stream actually contains many packets of data that are sent one at a time to the receiving machine.

relocatable. (1.) A value, expression, or address that does not have to be changed when the program is relocated. (2.) Attribute of a set of codes whose address constants can be altered to make up for a change in origin.

remote. Pertaining to a system or device that is accessed through a communications line. Contrast with local.

remote access data processing. Synonym for teleprocessing.

remote connection. A communications link between the local system and a remote system or device.

remote host. Any host on the network except the one at which a particular operator is working. Synonymous with foreign host.

remote job entry (RJE). Submission of a job through an input unit that has access to a computer through a data link.

remote login. Initiating a session on a system that is accessed through a communications line.

remote pacing. Pacing generated by the remote system attempting to control the output of the local system. See also pacing.

remote print. Issuing print jobs to one machine (client) to print on another machine (server) on a network.

remote procedure call (RPC). The calling of a remote operation between processes on different hosts or on the same host.

Remote Procedure Call run-time library. The set of rpc_$ system calls that NCS provides to implement a remote procedure call mechanism.

Remote Statistics Interface (RSi). In Performance Toolbox, the Manager API which allows an application program to access statistics from remote nodes (or the local host) through a network interface.

remote system. A system that is connected to your system through a communication line.

remote transaction program name (RTPN). The name of a transaction program at the other (remote) end of a conversation.

removable storage device. Any storage device defined during system configuration to be an optional part of the system DASD. A removable storage device can be removed from the system anytime during normal operation.

remove. For a software option, the deletion of the option and all of its applied or committed updates from the system. The software vital product data (SWVPD) information is changed to indicate that the option has been removed from the system. Depending on the option, system configuration information is also cleaned up, although this is not always complete. If a previous version, release, or level of the option is on the system, the system will not restore the previous version. Only an option with its updates can be removed. Updates cannot be removed by themselves. Contrast with commit.

renaming declaration. In Ada language, declares another name for an entity.

render. To create an image on a visual display from data that describes the scene.

rendezvous. In Ada language, the interaction that occurs between two parallel tasks when one task has called an entry of the other task, and a corresponding accept statement is being executed by the other task on behalf of the calling task.

repage fault. A page fault on a virtual-memory page that is known to have been read from disk "recently."

reparent. When a widget is moved between interface windows, it is reassigned to the parent widget in the new location, and automatically acquires the inheritable attributes of the new parent.

repeat factor. In GL, the magnification with which the linestyle pattern is used.

repetitive tiling operation. In XGSL, an operation that consists of repeatedly copying a 16x16-pixel tile rectangle (pointed to by the tile pixel map data address) to fill a rectangle area of a size specified by the H and W parameters of this call. The format defined in the flags field of the tile pixel map structure defines the format of the tile data.

replica. In SOM, when an object is replicated among a set of processes (using the Replication Framework), each process is said to have a replica of the object. From the view point of any application model, the replicas together represent a single object.

reply. (1.) A response to an inquiry. (2.) In SNA, a request unit sent only in reaction to a received request unit. For example, Quiesce Complete is the reply sent after receipt of Quiesce At End of Chain. (3.) In Enhanced X-Windows, the way information requested by a client program is sent back to the client. Both events and replies are multiplexed on the same connection. Most requests do not generate replies; some generate multiple replies.

representation clause. In Ada language, a clause that directs the compiler in the selection of the mapping of a type, an object, or a task onto features of the underlying machine that executes a program. In some cases, representation clauses completely specify the mapping; in other cases, they provide criteria for choosing a mapping.

request. (1.) A directive, by means of a basic transmission unit, from an access method that causes the network control program to perform a data-transfer operation or auxiliary operation. (2.) In SNA, a message unit that signals initiation of an action or protocol. (3.) In Enhanced X-Windows, a command to the server to send a single block of data over a connection. (4.) In text formatting, a request is a built-in command recognized by the formatters.

requester. A display station or interactive communications session that requests a program to be run.

required list. In Enhanced X-Windows, an ordered list containing a subset of the installed color maps.

required parameter. A parameter having no value automatically supplied. The user must provide a value.

required value. Synonym for required parameter.

requisite. A software product or a service update that must be installed with another software product or service update. If you attempt to install software products or service updates without the required requisite software, a system message displays the names of required requisite software.

reserved character. A character or symbol that has a special (non-literal) meaning unless quoted.

reserved word. A word that is defined in a programming language for a special purpose, and that must not appear as a user-declared identifier.

reset. (1.) To cause a counter to take the state corresponding to a specified initial number. (2.) To put all or part of a data processing device back to a prescribed state. (3.) On a virtual circuit, reinitialization of data flow control. (4.) To return a device or circuit to a clear state. (5.) In X.25 communications, to reinitialize the flow of control on a virtual circuit, which eliminates all data that may be in transit for the virtual circuit at the time of resetting.

reset cause. See cause code.

reset collision. See collision.

reset-confirmation packet. In X.25 communications, a packet transmitted by the data terminal equipment (DTE) to inform the data circuit-terminating equipment (DCE) that a reset operation has been processed. See also packet.

reset diagnostic. See diagnostic code.

reset packet . A packet used to reset a virtual circuit at the interface between the data terminal equipment (DTE) and the data circuit-terminating equipment.

reset-request packet. In X.25 communications, a packet used for the resetting of a virtual circuit at the DTE/DCE interface. See also packet.

resize border. In CDE, a control used to change the size of a window or a pane in a window.

resolution. The process or capability of making the individual parts of objects on screen distinguishable, especially regarding font generation. The number of dots that can be displayed on the screen. Used to determine the clarity of a graphic image.

resolver routine. A kernel process used to resolve symbolic host names into Internet addresses. The method the routine uses to resolve names depends on whether the local network is organized as a flat network or as a hierarchical network.

resource. (1.) In NIM, any file, directory, file system, or device that is required to perform a NIM operation. (2.) In Enhanced X-Windows, items such as windows, pixmaps, cursors, fonts, graphics contexts, and color maps are known as resources. Each has a unique identifier associated with it for naming purposes. The lifetime of a resource is bounded by the lifetime of the connection over which the resource was created. (3.) In Enhanced X-Windows, a named piece of data in a widget that can be set by a client, by an application, or by user defaults. (4.) In AIXwindows and Enhanced X-Windows, a unique characteristic of appearance or behavior that is associated with one specific class of graphical object. Resources can be passed downward (inherited) by each subclass that is downstream from a higher-level class in the class hierarchy.

resource database. The database assembled for a particular combination of display, host, and application. It can contain information from several sources.

resource identifier (rid). In Enhanced X-Windows, an integer returned to an application program that identifies a resource that has been allocated for the program's use.

resource limitation values. A set of values that Workload Management attempts to maintain for a set of resource utilization values. The resource limitation values are independent of the resource limits specified with setrlimit().

resource manager. A component that manages application data. Resource managers communicate with application servers.

resource object. A resource used in the Network Installation Management environment that represents a file or directory.

resource outage. The inability to obtain the necessary resources, such as links, buffers, or control block storage.

resource pair. See resource value.

resource state. A state that indicates that the resource is either available or unavailable for use.

resource string. A parameter, such as a part of the program name, that identifies an application's resources.

resource target share. The shares of a resource that should be available to a Workload Management class. These shares are used with other class shares to determine the desired distribution of the resources between classes.

resource utilization value. The amount of a resource that a process is currently using in a system. See also scope of resource collection.

resource value. Resources determine a widget or window's operation and attributes, such as color and behavior. The resource is associated with a value list that gives the specific values for each resource. See also attribute.

resource value string. A parameter containing the default value to be used if a specific resource has not been set.

response. (1.) An answer to an inquiry. (2.) In SNA, a message unit that acknowledges receipt of a request; a response consists of a response header (RH), a response unit (RU), or both.

response time. (1.)The time it takes for a data communications system to respond to a request. For example, if you enter a customer number on a workstation keyboard, response time begins when you press the last key and ends when the first character of your answer is displayed at the workstation. (2.) The time from the initiation of an operation until its initiator has enough information to proceed.

restart-confirmation packet. In X.25 communications, a call supervision packet transmitted by a DCE to confirm that the link has been restarted. See also packet.

restart-indication packet. In X.25 communications, a call supervision packet transmitted by a DCE to indicate to a DTE that a restart-request has been received.

restart-request packet. In X.25 communications, a call supervision packet transmitted by a DTE to request that a link be restarted.

restore. To return to an original value or image; for example, to restore a library from diskette.

restricted response. In X.25 communications, when restricted response is specified for a fast-select call, the call must be cleared; it may not be accepted.

restricted shell. Shell providing controlled, limited access to specified users.

result. An entity produced by an operation.

retransmit. To repeat the transmission of a message or segment of a message.

retrieval time. The time interval required to locate data in storage and read it for subsequent processing.

retry. To try the operation that caused the device error message again.

return code. (1.) A value that is returned to a program to indicate the results of an operation issued by that program. (2.) A code used to influence the running of succeeding instructions. Synonymous with return value.

return statement. A programming language control statement that contains the word return followed by an optional expression and a semicolon.

return value. Synonym for return code.

reverse charging. In X.25 communications, an optional facility that allows a DTE to request that the cost of a call it makes be charged to the called DTE. See also optional facilities.

reverse video. A form of highlighting a character, field, or cursor by reversing the color of the character, field, or cursor with its background. For example, changing a red character on a black background to a black character on a red background.

Revision Control System (RCS). Manages multiple revisions of text files. Designed to control frequently revised text, such as programs, form letters, and papers. It features automatic identification, storage, logging, retrieval, and merging of file revisions. See also Source Code Control System.

revision text. See version identifier.

rewind. To select an earlier item, rather than the next or current item, from an argument list.

RFC. Request for comments.

RFI. See radio frequency interference.

RGB color. A color value scale that is composed of the primary values (red, green, and blue).

RGB mode. A configuration of the hardware that allows values stored in the frame buffer to be interpreted as packed RGB values. The values found in the frame buffer are passed directly to the red, green, and blue guns of the display monitor. The values are not passed through the color map first. (However, each color is sent individually through the gamma ramp to make a final correction to its intensity.) See also color map mode.

RGB signal. Red/green/blue signal.

RGB value. The set of red, green, and blue intensities that compose a color is that color's RGB value.

RGBA value. In GL, the set of red, green, blue, and alpha intensities that compose a color. Alpha values are available only on machines having alpha bitplanes.

RIC. Realtime interface coprocessor.

rid. See resource identifier.

right-hand rule. If the right hand is wrapped around the axis of rotation, the fingers curl in the same direction as positive rotation, and the thumb points in the same direction as the axis of rotation. A right-handed rotation is counter-clockwise.

right margin. The area between the rightmost text character and the right edge of the display or paper.

ring. (1.) A method used to distribute data in a LAN. (2.) In FDDI, two or more stations connected by a physical medium wherein information is passed sequentially between active stations, each station is turn examining or copying and repeating the information, finally returning it to the originating station. See also ring network.

ring buffer. An application-defined buffer in which monitor mode input is placed. An application places data from input devices in the buffer. The ring buffer mechanism dramatically shortens the input data path from the input device to the application.

ring network. (1.) A network in which every node has two branches connected to it. (2.) A network configuration in which devices are connected by unidirectional transmission links to form a closed path. See also ring.

RIP. See Routing Information Protocol.

RISC. See Reduced Instruction Set Computer.

RJE. See remote job entry.

RMT. Ring management.

RNR frame. In X.25 communications, a receive-not-ready frame. Contrast with RR frame.

RNR packet. In X.25 communications, a receive-not-ready packet. Contrast with RR packet.

rolled back. Undoing any modifications performed on behalf of a transaction which does not complete (is aborted). Any changes made by a transaction which is aborted, for whatever reason, must be undone. Once a transaction is rolled back, no evidence that the transaction was ever attempted remains outside of records in the transaction processing system's log. See also abort.

roller ball. The sphere inside a mechanical mouse that contacts a desktop or other hard surface.

ROM. Read-only memory.

Roman font. The ordinary type style. In many typefaces, this is the default font, governing most text. It most often is used to turn off italics or boldface.

Roman numerals. Numbers formed from traditional combinations of Roman letters, either uppercase (I, II, III, IV, and so on) or lowercase (i, ii, iii, iv, and so on). See also Arabic numerals.

root. (1.) The user name for the system user with the most authority. (2.) In Enhanced X-Windows, (a.) The screen on which the window is created. The root of a pixmap or GContext is the same as the root of the drawable used when the pixmap or GContext was created. The root of a pixmap or graphics context is the same as the root of whatever drawable was used when the pixmap or graphics context was created. The root of a window is the root window under which the window was created. (b.) On the widget tree, the Shell widget returned by the XtInitialize or XtCreateApplicationShellsubroutine. (3.) In AIXwindows, the Shell widget is the root of the widget tree hierarchy that is maintained within any given application interface. See also widget tree.

root device. The device on which the root file system resides.

root directory. The directory (/) that contains all other directories in the system.

root file system. The basic file system, onto which all other file systems can be mounted. The root file system contains the operating system files that get the rest of the system running.

root segment. (1.) In an overlay operation, the part of a program that must remain in main storage when other overlay segments are run; the first segment of a program with overlays. The root segment remains in main storage at all times while the program is being run. (2.) In a hierarchical database, the highest segment in the tree structure.

root user. The person who has unrestricted ability to access and modify any part of the operating system, usually the user who manages the system. See also root user authority.

root user authority. The unrestricted ability to access and modify any part of the operating system, usually associated with the user who manages the system. See also root user.

root volume group (rootvg). A volume group containing the Base Operating System (BOS). See also migration installation.

root window. In a graphics environment, each screen has a root window covering it. This window cannot be reconfigured or unmapped, but otherwise performs like any other window. A root window has no parent.

ROS. Remote Operation Service.

ROSE. Remote Operation Service Elements.

rotation. In computer graphics, the transformation of a primitive by rotating it about an axis. See also transformation.

route. A path defined for sending data across a network.

routine. A set of statements in a program causing the system to perform an operation or a series of related operations. See also macro and subroutine.

routing. (1.) The assignment of the path by which a message will reach its destination. (2.) In SNA, the forwarding of a message unit along a particular path through a network as determined by parameters carried in the message unit, such as the destination network address in a transmission header. (3.) In X.25 communications, the process by which a packet gets to the intended user.

Routing Information Protocol (RIP). A variant of the XeroxNS Routing Information Protocol, used to maintain current kernel routing table entries.

routing list. The list that associates user names with network user addresses and other information, for the purpose of directing incoming X.25 calls.

routing table. The table holding a list of valid paths through which hosts can communicate with other hosts. The routing table can hold static routes and dynamic routes.

row. A horizontal arrangement of characters or other expressions.

row column manager. A widget that contains toggle buttons or push buttons. It updates its property that accounts for menu history, which allows it to determine which toggle button was selected last.

row-major order. A way of storing array elements such that the rightmost subscript varies most rapidly as memory-adjacent elements are accessed.

RPC. See remote procedure call.

rpm. Revolutions per minute.

RPN. See real page number.

RPOA. See recognized private operating agency.

RPQ. Request for Price Quotation.

RR. (1.) Resource Record (DNS). (2.) Round Robin (scheduling).

RR frame. In X.25 communications, a receive-ready frame. Contrast with RNR frame.

RR packet. In X.25 communications, a packet used by a DTE or by a DCE to indicate that it is ready to receive data packets within the window. Contrast with RNR packet.

RS-232C. See EIA-232D.

RS-422A. See EIA-422A.

RSi. See Remote Statistics Interface.

RTI. Response type indicator.

RTPN. See remote transaction program name.

RTS. Ready to Send used with EIA-232 Protocol.

rubber-band outline. A window with a moveable outline.

rule file. A file containing rules determining the appearance and behavior of Common Desktop Environment.

run. (1.) A performance of one or more jobs or programs. (2.) To cause a program, utility, or other machine function to be performed.

run file. The output of the linkage editor. A program file in a format that is suitable for being loaded into main storage and run. See also module.

run-time algorithm selection. An optimization technique in which the parameters to an operation are evaluated to determine which of several equivalent algorithms will perform the operation most efficiently.

run-time checks. Error checking that occurs while an Ada program runs. If an error is detected, the program raises an exception.

run-time environment. A collection of subroutines and shell variables that provide commonly used functions and information for system components.

run-time monitor. The part of the Monitor that manages transactional client and server applications that take input from users and service requests.

running state. The condition of a machine when users can login and use the machine.

RW lock. Abbreviation for read shared/write exclusive lock. Any number of threads can hold the lock simultaneously for reading, but if a thread holds the lock for writing, all other threads are excluded from reading or writing the locked resource.

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