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rack: A free-standing structure or frame that can hold multiple servers and expansion units.
rack configuration list: A list of all of the equipment within the rack and the logic cards within the card enclosure.
rack stabilizer: A plate that holds the rack stable or steady when a device is pulled out for service.
RACL: See Random Automated Cartridge Loader.
radio button: A circle with text beside it that indicates a fixed set of choices from which only one can be selected. The circle is partially filled when a choice is selected.
radix-tree index: In DB2® UDB for iSeries™, an object that provides random access to rows in a database table. See also encoded-vector index.
RAID: See Redundant Array of Independent Disks.
RAID 5: A form of parity RAID in which the disks operate independently, the data stripe size is no smaller than the exported block size, and parity check data is distributed across the array's disks
RAID 6: Any form of RAID that can continue to execute read and write requests to all of an array's virtual disks in the presence of two concurrent disk failures.
rail: Hardware attached inside a rack to hold devices that are designated as installable in a rack. See also slide.
RAM: See random access memory.
random access: In COBOL, an access method in which the program-specified value of a key data item identifies the logical record that is obtained from, deleted from, or placed into a relative or indexed file.
random access memory (RAM): Computer memory in which any storage location can be accessed directly. See also disk unit.
Random Automated Cartridge Loader (RACL): A cartridge loader that includes individual drives that can have their own facility to use an automated tape library.
random by key: A processing method for files in which the value in the key field identifies the records to be processed.
random by relative record number: A processing method for files in which relative record numbers identify the records to be processed.
random number: A number obtained by chance. See also pseudorandom number.
random processing: A method of processing in which records can be read from, written to, or deleted from a file order requested by the program that is using them. See also consecutive processing, sequential processing.
raster pattern: A series of picture elements (pels) arranged in scan lines to form an image. The toned or untoned status of each pel creates an image. A digitized raster pattern is an array of bits. The on or off status of each bit determines the toned or untoned status of each pel.
rational number: A real number that is the quotient of an integer divided by an integer other than zero.
RBR: See rollback required.
RC: A REXX special variable set to the return code from any executed host command or subcommand. It is also set to the return code when the conditions ERROR, FAILURE, and SYNTAX are trapped.
RCB: See record control byte.
RCD: See read cache device.
RCMS: See remote change management server.
RDB: See relational database.
RDB directory: The directory where remote databases in the network are registered. Information in a directory tells the system which communications parameters to use to connect to a remote database. The RDB directory also contains the name of the local database.
RDBMS: See relational database management system.
RDN™: See relative distinguished name.
RDO: See resource definition online.
read authority: (1) An authority subset that allows the user to read entries in an object. The system-recognized identifier is *R. *R authority combines object operational authority and read authority.; (2) A data authority that allows the user to look at the contents of an entry in an object.
read cache device (RCD): A volatile solid-state disk that is optimized for use as memory for the extended adaptive cache.
reader: (1) In RJE, a program that reads jobs from a database file or interactive display station and sends them to the host system.; (2) An internal program that reads jobs from an input device or a database file and places them on a job queue.
read/execute authority: An object authority that allows the user to read entries in an object, run a program, and search a library or directory. Read/execute authority combines object operational authority, read authority, and execute authority. The system-recognized identifier is *RX.
read-from-invited-program-devices operation: An input operation that waits for input from any one of the invited program devices for a user-specified time. See also read-from-one-program-device operation.
read-from-one-program-device operation: An input operation that will not complete until the specified device has responded with input. See also read-from-invited-program-devices operation.
read-only memory (ROM): Memory in which stored data cannot be changed by the user except under special conditions.
read operation: An input operation that obtains data from a file or device and passes it to a program.
read stability: In DB2 UDB for iSeries, an isolation level that does not completely isolate an application process from all other application processes that are running concurrently. At the read stability level, an application that issues the same query more than once might read additional rows (phantom rows) that were inserted and committed by an application process that is running concurrently. See also repeatable read.
read/write authority: An object authority that allows the user to add, change, delete, and read entries in an object. Read/write authority combines object operational authority, read authority, add authority, update authority, and delete authority. The system-recognized identifier is *RW.
read/write/execute authority: An object authority that allows the user to add, change, delete, and read execute entries in an object, run a program, and search a library or directory. Read/write/execute authority combines object operational authority, read authority, add authority, update authority, delete authority, and execute authority. The system-recognized identifier is *RWX.
read/write head: The data sensing and recording unit of the diskette drive or tape drive.
ready: Pertaining to a status where all the loaded and mounted image catalog entries are available for use by the active virtual optical device. Any image catalog entry with a status of unloaded is not available for use by the virtual optical device. The image catalog can be made ready by using the LODIMGCLG (Load Image Catalog) command with OPTION(*LOAD).
realm: In the Kerberos protocol, the set of principals for which a specific key distribution center (KDC) is the authenticating authority.
realm trust: The Kerberos protocol either searches the configuration file to determine realm trust or by default looks for trust relationships within the realm hierarchy. Using Trusted realms in network authentication service allows you to bypass this process and creates a shortcut for authentication. Realm trust can be used in networks where realms are in different domains. For example, if a company has one realm at NY.myco.com and another at LA.myco.com, then you can establish trust between these two realms. If two realms trust each other their associated KDCs must share a key. Before creating a shortcut, you must set up the KDCs to trust each other.
real-time: 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. (I)(A)
reason code: A return code that describes the reason for the failure or partial success of a Message Queue Interface (MQI) call.
reassembly: In OSI, a function performed by an (N)-entity to map multiple (N)-protocol-data-units into one (N)-service-data-unit. Reassembly is the opposite of segmenting. See also segmenting.
reassign: To mark a disk sector as damaged. The marked disk sector points to another sector location where the data from the damaged sector is moved.
reattach: In cross-site mirroring, to reassociate the mirror copy with its production copy after user operations on the mirror copy are complete. When the mirror copy is reattached, it is automatically synchronized to match the production copy again. All data on the mirror copy prior to when it is reattached to the production copy is cleared.
rebind: (1) To request renewal of a lease from a server on a particular network.; (2) To create a package for an application program that was previously bound. For example, if an index is added for a table that is accessed by a program, the package must be rebound for it to take advantage of the new index.
rebuild maintenance: A method of maintaining keyed access paths for database files. This method updates the access path only while the file is open, not when the file is closed; the access path is rebuilt when the file is opened. See also delayed maintenance, immediate maintenance.
receive mode: A time during which the BSC adapter looks for synchronization characters, and stores the data characters in main storage.
receive not ready (RNR): In communications, a data link command or response that indicates a temporary condition of being unable to accept incoming frames.
receiver: In hardware, a functional unit that converts small electronic signals to signals that control a device.
receiver chain: The journal receivers presently or previously attached to the same journal. Each journal receiver, except the first one, has a previous receiver that was attached before the current receiver. Each journal receiver, except the currently attached receiver, has a next receiver.
receiver chain break: A logical break in a receiver chain.
receiver directory: Summary information about the journal receivers that are or were attached to the specified journal and are still known to the system.
receive ready (RR): In communications, a data link command or response that indicates that a station is ready to receive protocol data units. Receive ready also acknowledges receipt of protocol data units.
receive timeout: In data communications, a condition that occurs when no data is received in a given period of time.
receiving cross-domain key: In Cryptographic Support, a cross-domain key used to decrypt a data-encrypting key that was encrypted by another location.
receptacle: A hollowed electrical fitting that contains the live parts of a circuit.
recipient address: A string of data that represents the address associated with the recipient of the message. The contents and format of the string are not defined by the mail server framework. The address type associated with the recipient address is assumed to define the contents of the recipient address field.
recipient history tree: A structure that represents the changes to the recipient list, so that a recipient can be traced back to the recipient entry in the original recipient list passed using the Create Mail Message application program interface (API).
recombining: In OSI, a function performed by an entity that is the reverse of splitting.
Recommendation X.21 (X.21): A document, CCITT Recommendation X.21, that outlines standards for a general-purpose interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) for synchronous operations on a public data network.
Recommendation X.21 bis: A document, CCITT Recommendation X.21 bis, that outlines standards for the interface between data terminal equipment (DTE) and V-series data circuit-terminating equipment (DCE) for synchronous operations on a public data network.
Recommendation X.31: A document, CCITT Recommendation X.31, that outlines standards for the X.25 protocol over integrated services digital networks (ISDNs).
record: (1) A group of related data, words, or fields treated as a unit, such as one name, address, and telephone number.; (2) In COBOL, the most inclusive data item. The level-number for a record is 01. A record can be either an elementary item or a group item.
record address file: In RPG, an input file that indicates which records are to be read from another file and the order in which the records are to be read.
record area: In COBOL, a storage area in which a record described in a record description entry in the File Section is processed.
record control byte (RCB): In multileaving telecommunications access method (MTAM), a control character used to identify each record type within a transmission block.
record description entry: In COBOL, the total set of data description entries associated with a particular record.
record format: A named part of a file that identifies records of a specified record format description.
record format definition: In IDDU, information that describes the arrangement or layout of fields in a record. A record format definition resides in a data dictionary.
record format description: A description of the characteristics of the fields (for example, type and length) and the arrangement of the fields in a record created by the user.
record ID code: See record identification code.
record identification code (record ID code): Characters placed in a record to identify the record format.
record identifying indicator: An indicator that identifies the record just read.
record key: (1) In COBOL, a key field whose contents identify a record within an indexed file.; (2) In RPG, all the key fields defined for the record type.
record layout: In AFP™ Utilities, a part of the printout format definition that defines how each field of a database file record is formatted and printed by the print format utility.
record-level specifications: Data description specifications coded on the same line as a record format name or on lines immediately following a record format name (until the first field is specified).
record name: In COBOL, a user-defined word that names a record described in a record description entry in the Data Division of a COBOL program.
record number: In COBOL, the ordinal number of a record in the file whose organization is sequential.
record selection: The process of selecting particular records from a file and including the information from the records, for example, in a report.
record separator: In BSC, a control character used to indicate the end of one record and the beginning of another.
record type: The classification of records in a file. Records of the same type have the same fields in the same order. For program-described files, these records have record identification codes; for externally described files, the records have the same record format name.
recoverability: The degree or extent to which the system can be restored to an operational condition after a system failure.
recovery: (1) In Backup Recovery and Media Services, the process of locating and restoring data in the event of partial or total data destruction. The recovery service automatically locates the correct media to be restored based on user-defined media management and recovery requirements.; (2) The process of rebuilding a database or table space that has become unusable because of hardware or software failure, or both. The process can involve the restoration of a backup image and the use of database logs or journals to reconstruct the changes that occurred to the database.
recovery domain: A subset of nodes in a cluster that are grouped together for a common purpose, such as rebuilding databases after a system failure. A domain represents those nodes of the cluster where cluster resource exists.
recovery library: The library containing information related to recovery of database operations from system failures. Named QRECOVERY.
recovery policy: In Backup Recovery and Media Services, a policy that defines the default controls and values to be used in recovery operations.
recursion: A programming technique in which a program or routine calls itself to perform successive steps in an operation, with each step using the output of the preceding step.
recursion level: The position of a program in a call stack. The first occurrence of a program in a job has a recursion level of 1, the second occurrence of the same program has a recursion level of 2, and so on.
recursive: Pertaining to a program or routine that calls itself after each run until it is interrupted.
recursive mutex: A read/write lock that is acquired again by the owning thread.
recursive procedure: An active procedure that can be called from within itself or from within another active procedure.
recursive program: A program that can call itself, or be called by another program, and repeat indefinitely until a specified condition is met.
reduced instruction set computer (RISC): A computer that uses a small, simplified set of frequently used instructions for rapid processing. See also complex instruction set computer.
Redundant Array of Independent Disks (RAID): A collection of two or more disk physical drives that present to the host an image of one or more logical disk drives. In the event of a single physical device failure, the data can be read or regenerated from the other disk drives in the array due to data redundancy. See also device parity protection, array.
reentrant: The attribute of a program or routine that allows the same copy of the program or routine to be used concurrently by two or more tasks.
reference: In VisualAge® RPG, information from a physical source file that may be extracted at build time. Any changes made to the original source must be recompiled to reflect the changes at run time.
reference code: A group of characters that identifies the machine status or a specific error condition.
reference code translation table: An object that contains reference code and field-replaceable-unit (FRU) code records. These records are used to report hardware errors and do problem analysis and resolution. The system-recognized identifier for the object type is *RCT.
referenced window record: In DDS, a record containing the WINDOW keyword that identifies the name of a window definition record.
reference format: A format that provides a standard method for describing COBOL source programs.
reference line: In Business Graphics Utility, a straight line parallel to either the vertical or horizontal axis relative to which data values are plotted on a chart. Sometimes called a translated axis line.
reference modification: In COBOL, a method of establishing and referring to a data item by specifying a leftmost character position and length within a character string.
reference modifier: In COBOL, the leftmost character position and the length of a character string used to establish and refer to a data item.
reference modify: To establish and refer to a COBOL data item by specifying a leftmost character position and length within a character string.
reference phrase: The text that is highlighted and preceded by a single-character input field used to signify the existence of a hypertext link.
referential constraint: The requirement that the nonnull values of a designated foreign key are valid only if they also appear as values of the primary key of the parent table. The referential constraint is always defined from the perspective of the dependent file. See also relationship, unique constraint.
referential cycle: (1) A set of referential constraints such that each table in the set is a descendent of itself.; (2) See constraint cycle.
referential integrity: The state of a database in which all values of all foreign keys are valid. Maintaining referential integrity requires the enforcement of a referential constraint on all operations that change the data in a table where the referential constraints are defined.
referral: In the Lightweight Directory Access Protocol (LDAP), a pointer from one LDAP directory server to another.
reflective marker: In hardware, reflective material placed on magnetic tape to indicate the beginning or ending of the recording area.
register: (1) To insert authorization and authentication information into binding information.; (2) In the hierarchical file system, to make an underlying file system and the specific functions it supports known to the application programming interface layer and accessible to user applications.; (3) An internal computer component capable of storing a specified amount of data and accepting or transferring this data rapidly.
registered enterprise-unique identifier: A name given to an entire network that makes the network unique among other networks, including IBM® networks. New users are requested to register the network name with IBM if they plan to communicate with IBM networks (for PTF information, for example).
registered filter: A filter that allows more than one active filter for alerts and problem logs. When a filter is registered, the system can send notification of events to a data queue. Registered filters behave slightly different than filters exposed through the network attributes or system value commands.
registration: (1) In X.25, the process used between a DTE and a DCE to establish an agreement on which optional user facilities will be in effect. For example, the DTE can request that the DCE agree to or stop a previous agreement for an optional user facility. Also, a DCE can indicate which optional user facilities are available or which optional user facilities are currently in effect. The negotiation is accomplished through the exchange of registration packets.; (2) In OSI, the process of obtaining identifiers for objects from the appropriate naming authorities. Registered identifiers should be obtained for the following objects, which relate to OSI Communications Subsystem operations: (a) NSAP addresses, (b) DTE addresses, (c) abstract syntaxes, (d) application contexts, and (e) application entities.
registration facility: A service that provides storage and retrieval operations for i5/OS™ and non-i5/OS exit points and exit programs.
registration facility repository: The repository that contains information about the i5/OS and non-i5/OS exit points and exit programs.
registry database: In a z/OS® or OS/390® environment, a database of security information about principals, groups, organizations, accounts, and security policies.
REJ: See reject.
reject (REJ): In communications, a data link command or response used to request the resending of information frames.
rejoin: To become an active member of an entity after having been a nonparticipating member.
relational character: In COBOL, one of the characters that express a relationship between two operands: = (equal to), > (greater than), < (less than).
relational checking: (1) The evaluation of the operands in a relational expression, based on the relational operator used.; (2) In RPG, tests performed against two statements in a source program to ensure that the statements are valid (for example, a GOTO operation must have an associated TAG operation). This type of checking is done only by the compiler as opposed to single-statement syntax checking that is done by the SEU function.
relational condition: In COBOL, a condition that relates two arithmetic expressions, data items, or both.
relational data: Data stored in a relational database management system (DBMS).
relational database (RDB): A database that can be perceived as a set of tables and manipulated in accordance with the relational model of data. Each database includes a set of system catalog tables that describe the logical and physical structure of the data, a configuration file containing the parameter values allocated for the database, and a recovery log with ongoing transactions and archivable transactions.
relational database management system (RDBMS): A collection of hardware and software that organizes and provides access to a relational database.
relational expression: A logical statement that describes the relationship (such as greater than or equal to) of two arithmetic expressions or data items.
relational operator: (1) Any of the set of operators that express an arithmetic condition that can be either true or false. The operators are: .GT., .GE., .LT., .LE., .EQ., and .NE.. They are defined as greater than, greater than or equal to, less than, less than or equal to, equal to, and not equal to, respectively.; (2) The reserved words or symbols used to express a relational condition or a relational expression.; (3) In COBOL, a reserved word, a relational character, a group of consecutive reserved words, or a group of consecutive reserved words and relational characters used to express a relational condition.
relationship: In the Application Development Manager feature of the Application Development ToolSet licensed program, a definition of the dependency between two parts.
relative data: In Business Graphics Utility, values in a computer image that specify points relative to other points in the image.
relative distinguished name (RDN): The part of an object name that is an attribute of the object itself.
relative end position: In RPG, an entry on the output specifications that indicates the number of blank positions that are to appear between a field or constant defined on one specification line and the field or constant defined on the preceding specification line. See also exact end position.
relative file number: In the DDS for a join logical file, a sequential number assigned to a physical file based on the position of that file on the JFILE keyword specification.
relative host name: The specific subname of a fully qualified host name. For example, smith is a relative host name for smith.endicott.ibm.com.
relative key: In COBOL, an unsigned number that can be used directly by the system to locate a record in a file.
relative-name format: A print descriptor naming convention that uses group alias names instead of system-specific (actual) group names.
relative organization: In COBOL, the file organization in which each record is uniquely identified by a positive number value that specifies the position in the file relative to the first record.
relative path name: A string of characters used to refer to an object, starting at some point in the directory hierarchy other than the root. A relative path name does not begin with a slash (/). The starting point is frequently a user's current directory. See also absolute path name.
relative positional pattern: In REXX, the part of a parsing template that uses a plus or minus sign to indicate movement relative to a previous pattern match.
relative record number: (1) In COBOL, the ordinal number of a record in a file whose organization is relative. This number is treated as a numeric constant that is an integer.; (2) A number that specifies the relationship between the location of a record and the beginning of a database file, member, or subfile. For example, the first record in a database file, member, or subfile has a relative record number of 1.
relative-size pie: In Business Graphics Utility, a piece on a pie chart drawn proportionally to another piece.
relay agent: A program that delivers Dynamic Host Configuration Protocol (DHCP) packets to a local system.
relay node: See relay open system. See also adjacent destination node.
relay open system: In OSI architecture, an open system that forwards data received from one open system to another open system. (T) See also adjacent destination node.
release: A distribution of a new product or new function and authorized program analysis report (APAR) fixes for an existing product. The first version of a product is announced as Release 1 Modification Level 0.
released state: The state of a connection that results in a disconnect of the connection at the next commit operation. See also held state.
release lever: A part that unlocks the device so it can be pulled out of the rack on the slides.
release-program-device operation: An operation that makes a program device not available for input/output operations. See also acquire-program-device operation.
release token: In OSI, the token that controls the orderly release of an association.
reliable transfer server (RTS): In OSI X.400, a portion of X.400 that is responsible for creating and maintaining application associations and for reliably transferring distributions between message transfer agents.
REM: See ring error monitor.
remote: Pertaining to a system, program, or device that is accessed through a communications line.
Remote Abstract Window Toolkit for Java™: An implementation of the Abstract Window Toolkit (AWT) that allows Java applications to run on a host system that does not have a graphical user interface (GUI). The server does not support locally attached graphic workstations; therefore Remote AWT is necessary to allow graphical Java applications to run on the server.
Remote Access Dial-In User Service: A server that authenticates a user's password and identification before sending the information on to an Internet Service Provider (ISP) server. The server also maintains accounting records of network usage for separate users. TCP/IP services and applications, such as Point-to-Point Protocol (PPP), can rely on a RADIUS server for authentication and accounting functions.
Remote Access Service: Windows NT® software that provides network capabilities over a modem link and contains functions that support point-to-point wide area network connections. For i5/OS, this includes both outgoing (originator) and incoming (receiver) point-to-point profile types and other services such as Remote Access Dial-in User Service (RADIUS) and Dynamic Host Configuration Protocol (DHCP) client configuration. Operations Console requires Windows NT users to have Remote Access Service.
remote agent: In OSI, an agent process on a remote node. See also local agent.
remote application entity: In OSI, an application entity on a remote node.
remote application process: In OSI, an application process on a remote node. See also local application process.
remote bus adapter: A bus adapter in an expansion unit. Optical cables from the local optical link cards in the system unit plug into this card.
remote change management server (RCMS): In retail communications and Point-of-Sale Utility, a store controller program communicating over an SNA/SDLC network that connects a host processor and a store controller. RCMS allows the NetView® Distribution Manager program to access point-of-sale controller files. It also provides error reporting and recovery for failures and data format conversion for files.
remote console: (1) The display device that qualifies as a system console but is not directly attached to a system. See also local console.; (2) An Operations Console configuration that allows a personal computer to dial into a local console to gain console access to the system. See also Operations Console.
remote controller: A device or system, attached to a communications line, that controls the operation of one or more remote devices. See also local controller.
remote control panel: A graphical interface that is provided by Operations Console that allows control panel operations to be performed from a remote location. This interface allows personal computer access to the control panel that controls operating or servicing the system.
remote device: A device that is connected to a computer over a telecommunication line. See also local device.
remote directory access: In OSI, the process of accessing directory information that resides on a remote open system.
remote directory service: In OSI, the service that enables a system to obtain directory service from another system. In OSI Communications Subsystem, remote directory service requires the availability of a directory system agent (DSA) from which a directory user agent can obtain directory services using the X.500 directory access protocol (DAP).
remote directory system agent: In OSI, an application process on a remote node that provides directory service.
remote equipment: The modem and controller that provides the communications connection between a communications line and a remote device or system. This remote equipment is at the other end of a data link from the host system.
remote input/output (RIO): A type of hardware architecture that facilitates faster input/output connection speeds between a system unit and expansion units.
remote job entry: The submission of a job through an input unit that has access to a computer by means of a data link.
remote journal network: An i5/OS environment that includes a primary system source journal and target system journals. The target system journals, associated by using the remote journal function, are downstream from the primary system source journal.
remote location name: Any other system with which a user's system can communicate in a network. This corresponds to the remote location name specified in the communications configuration. Equivalent to an SNA remote logical unit name. See also local location name.
remote manager: In OSI, a managing process on a remote node. See also local manager.
Remote Method Invocation (RMI): A protocol that is used to communicate method invocations over a network. Java Remote Method Invocation is a distributed object model in which the methods of remote objects written in the Java programming language can be invoked from other Java virtual machines, possibly on different hosts.
remote name server: (1) A name server that exists outside a local network.; (2) In TCP/IP, the function that allows a system to get an internet address from a remote site rather than from its own host table.
remote network address: In OSI, a network address that identifies a remote node.
remote node: In OSI, any node other than the local node. See also local node.
remote NSAP: In OSI, a service access point in the network layer of a remote node.
remote presentation address: In OSI, a presentation address of an application entity on a remote node. See also local presentation address.
remote printer queue: The name of a printer queue on a remote system. For a remote system running i5/OS, this is the name of an output queue on the remote system.
remote procedure call (RPC): A protocol that allows a program on a client computer to run a program on a server.
remote queue: A queue that belongs to a remote queue manager. Programs can put messages on remote queues, but they cannot get messages from remote queues. See also local queue.
remote queue manager: To a program, a queue manager that is not the one to which the program is connected. See also local queue manager.
remote queuing: In message queuing, the provision of services to enable applications to put messages on queues belonging to other queue managers.
remote service requester: In OSI, a service requester process on a remote node. See also local service requester.
remote system: Any other system in the network with which your system can communicate. See also local system.
remote terminal access method (RTAM): A function of IBM System/370-type computers that controls operations between the Job Entry Subsystems (JES2) (JES3) and remote work stations on the iSeries system.
remote unit of work (RUOW): (1) A unit of work that allows for the remote preparation and execution of SQL statements.; (2) The form of SQL distributed processing in which the application is on a system different from the relational database, and a single application server services all remote unit-of-work requests within a single logical unit of work.
remote workstation: A workstation that is connected to the system by data communications. See also local workstation.
remote writer: A system program that sends spooled files from an output queue to a remote system.
removable media: Volumes that can be removed from the hardware devices (such as tape cartridges and optical disks) where they are read and written.
renewable tickets: A ticket that contains two expiration times: one that applies to the current instance of the ticket, and one that applies to the latest permissible expiration of the ticket. Renewable tickets are valid for an extended period of time while lessening the changes for theft.
repeatable read: In DB2 UDB for iSeries, an isolation level that completely isolates an application process from all other application processes that are running concurrently. At the repeatable-read level, rows read during a unit of work cannot be changed by application processes that are running concurrently until the unit of work is complete, rows changed by application processes that are processing concurrently cannot be read until they are committed by that application process, and phantom rows are prevented. See also read stability.
repetitive DO loop: In REXX, any instruction that has either a repetitor phrase or a conditional phrase (or both). The instruction list within the instruction is run zero or more times, controlled by any repetitor phrase that is optionally changed by a conditional phrase.
replica: In the Lightweight Directory Access Protocol (LDAP), a read-only server that contains the same data as another server. Replicas are used to back up LDAP servers and to provide faster searches by splitting requests among the main server and replica servers.
replicate: In a remote journal network, to make a duplicate copy of a journal entry from a source journal to a target journal.
replicate node: A complete copy of a cluster resource that is kept up to date through replication. A node that is designated a replicate node cannot become a backup node or a primary node.
replication: The process of copying objects from one node in a cluster to one or more other nodes in the cluster, which makes the objects on all the systems identical.
reply message: A type of message used for replies to request messages. See also report message, request message.
reply-to address: A string of data that represents the address to be replied to. The contents and format of the string are not defined by the mail server framework. The address type associated with the reply-to address is assumed to define the contents of the reply-to address field.
reply-to queue: The name of a queue to which the program that issued an MQPUT call wants a reply message or report message sent.
report: In query management, the formatted data that results from running a query and applying a form to it.
report break: In Query, a blank line or new page that appears in a report when the contents of a specified field in the report change. A report break can contain column summaries.
reporting node: In OSI, a node that reports a message to a manager node.
report layout utility (RLU): A function of the Application Development ToolSet licensed program that is used to create, change, and save report prototypes.
report line: In RLU, a record that is part of a report prototype for which the user creates data description specifications (DDS).
report message: A type of message that gives information about another message. A report message can indicate that a message has been delivered, has arrived at its destination, has expired, or could not be processed for some reason. See also reply message, request message.
Report Program Generator (RPG): A programming language designed for writing application programs for business data processing requirements. The application programs range from report writing and inquiry programs to applications such as payroll, order entry, and production planning.
report prototype: In RLU, a representation of the image of a report that a user builds on a display and the printed report image, both of which look like the actual listing created by an application program. The report prototype, when saved as a DDS source member, can be used to create a printer file, which, in turn, can be used by an application program to create a report.
request: In OSI, a service primitive issued by a service user to call a function supported by the service provider.
requester: (1) In iSeries Access, a program that requests services from another program (a server). Each iSeries Access function has a server and a requester.; (2) A workstation from which a user can log on to a domain and use network resources.
request for price quotation (RPQ): A customer request for a price quotation on alterations or additions to the functional capabilities of a hardware product for a computing system or a device. See also programming request for price quotation.
request functional transmission: In multileaving telecommunications access method (MTAM), a control character indicating a request for permission to send data. See also grant functional transmission.
request header (RH): In SNA, a 3-byte header that precedes a request unit. The request header specifies the type of request unit and contains control information associated with that request unit. See also response header.
request message: A type of message used to request a reply from another program. See also reply message, report message.
request/reply: A type of messaging application in which a request message is used to request a reply from another application.
request unit (RU): In SNA, a message unit that contains control information such as a request code, or function management (FM) headers, end-user data, or both.
required hyphen: A hyphen that is not removed when the program adjusts lines. See also syllable hyphen.
reservation: In QoS, part of a resource that has been dedicated for the use of a particular traffic type for a period of time through the application of policies.
reserved memory: The area of main storage between 640 KB and 1 MB on a personal computer. Reserved memory cannot be used by adapters and special programs, such as expanded memory support.
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 (RST): The reset logical unit of work (LUW) state indicates that the current LUW has not yet begun to prepare to commit. A failure during RST state results in a rollback of any pending changes.
residual error: An error that is not detected by the network layer. Examples of residual errors are loss, corruption, duplication, and delivery out of sequence of TPDUs. See also signaled error.
resilient application: A server program that can be restarted on a different node without requiring a user to reconfigure the clients.
resilient resource: Data, a process, or an application that can be recovered if a node in a cluster fails.
resolution: A measure of the sharpness of an image, expressed as the number of lines per unit of length or the number of points per unit of area discernible in that image.
resolve: In programming, to change a predefined, symbolic value to the actual value of the item being processed. For example, a symbolic value of *LAST defined for the name of a file member is resolved to the name of the last member when the member is processed.
resolved import: An import whose type and name exactly match the type and name of an export.
resource: (1) Any physical item or logical item to be managed in an information system of an enterprise.; (2) Any facility of a computing system or operating system required by a job, task, or executing program. Resources include main storage, input/output devices, the processing unit, data sets, files, libraries, folders, and control or processing programs. In WebSphere® MQ for z/OS, examples of resources are buffer pools, page sets, log data sets, queues, and messages.
resource definition online (RDO): In CICS® , a facility that allows the user to define certain CICS resources interactively while CICS is running. Specifically, RDO allows the user to define terminals, programs, and transactions interactively.
resource error counters: In OSI, counters that keep track of errors that occur in layers and other resources.
resource management: In CICS , a facility that tracks what system resources are being used. The tracking is done by mapping the CICS identification name to the underlying system resources.
resource management utility (RMU): In AFP Utilities, an interactive tool used to maintain AFP resources.
resource name: A name assigned by the system to a line, controller, or device that is connected to the system.
resource record (RR): In a Domain Name System (DNS), a location where data is stored.
resource reservation setup protocol: An Internet protocol that is used for communicating application (end-to-end) quality-of-service requirements to intermediate transit nodes in a network. RSVP uses a soft-state mechanism to maintain path and reservation states in each node in the reservation path.
resource security: A security function of the operating system used to authorize users to any part of the system that is required by a job or task.
resource tables: Related types of resource information that are stored within CICS in tables or control blocks.
responder: (1) A key server that is asked to establish a dynamic virtual private network (VPN) connection between two endpoints.; (2) In OSI Communications Subsystem, the application entity that accepts an application association. See also initiator.
response: (1) In SDLC, a frame transmitted by a secondary station. Stations using asynchronous balanced mode send both commands and responses.; (2) In OSI, a service primitive issued by a service user to complete the procedures associated with a confirmed service. See also command.
response header (RH): In SNA, a header, optionally followed by a response unit, that indicates whether the response is positive or negative and that may contain a pacing response. See also request header.
response indicator: A 1-character field passed with an input record from the system to a program to provide information about the data record or actions taken by the workstation user.
response mode: A mode of terminal operation that synchronizes operations between the terminal operator and the application program. When IMS™ receives an input transaction that causes response mode to be entered, no more input is allowed until the application program response has been transmitted back to the terminal. See also nonresponse mode.
response time: In capacity planning, the elapsed time between the end of an inquiry or demand on a computer system and the beginning of the response. An example of response time is the length of time between an indication of the end of inquiry and the display of the first character of the response at a user's workstation.
response unit (RU): In SNA, the record sent to respond to a request. The response can be either positive or negative and can include control information.
restore: (1) To return to an original value or image; for example, to restore data to main storage from auxiliary storage. ant: backup; (2) To copy data from compact disc, tape, diskette, optical disc, or a save file to auxiliary storage. See also save.
restricted state: The status in which a user places a system (by ending all subsystems) to do a specific function, such as saving storage, saving the system, or restoring user profiles. Other jobs cannot be active on the system while it is in a restricted state.
Restructured Extended Executor (REXX): A general-purpose, high-level, programming language, particularly suitable for EXEC procedures or programs for personal computing.
RESULT: A REXX special variable that is set by the RETURN instruction in a called routine. The RESULT special variable is dropped if the called routine does not return a value.
result column: The set of columns that DB2 UDB for iSeries SQL selects for an application program.
result field: In Query, a field that contains the results of calculations performed on numeric fields in a file.
resulting indicator: In RPG, an indicator that signals the result of a calculation, such as whether the result is plus, minus, or zero; whether a given field is greater than, less than, or equal to another field; or whether an operation was successfully completed.
result table: The set of rows that DB2 UDB for iSeries SQL selects for an application program. The program uses a cursor to retrieve the rows one by one into a host structure or a set of host variables.
resume: In cross-site mirroring, to start geographic mirroring again after it is suspended.
resume cursor: A pointer that tracks the current location at which the exception handler may resume processing after handling an exception.
resume pending state: In cross-site mirroring, the configuration state of a mirror copy that indicates that geographic mirroring requires synchronization but that the disk pool is currently unavailable. When the disk pool is made available, the mirror copy will be synchronized with the current information on the production copy.
resume point: An instruction in a program where processing continues after handling an exception.
resuming state: In cross-site mirroring, the configuration state of the mirror copy that attempts to perform geographic mirroring and synchronization when the independent disk pool is available. The mirror copy state is resuming when it is not suspended or active.
resynchronize: In OSI, a function of the session layer that enables two peers to coordinate the exchange of data to a previously marked point. This point was marked using the major or minor synchronization service. Resynchronization will normally be performed after a problem is detected by an application entity or indicated by the session layer.
retail communications: The data communications support that allows programs on an iSeries system to communicate with programs on point-of-sale systems, using SNA LU session type 0 protocol.
retail controller: In retail communications and Point-of-Sale Utility, a controller in a network that is used to collect data from and provide support for the point-of-sale and administrative devices within the retail system. The retail controller also provides some local data processing capabilities.
retail pass-through: An i5/OS system program that supports routing of user data between a System/370-type host processor and a retail controller using a single iSeries system. Both the SNA upline facility and the retail communications support use separate intersystem communications function sessions.
retention: In Backup Recovery and Media Services, the total length of time that the output media is to be saved as a backup or archive copy before it is expired (available for reuse). Retention can be specified as a date, number of days, versions, or permanent. Different retention periods can be specified for full backups, incremental backups, or archive output.
retrofit: To change an existing program or system by adding or replacing a section of code or a physical unit and making necessary modifications to related units.
retry: Pertaining to that which resends data a prescribed number of times or until the data is received correctly, for example, a retry option or a retry loop.
return: To remove the call stack entry and transfer control back to the calling procedure or program in the previous call stack entry.
return code: For printer files, display files, and ICF files, a value sent by the system to a program to indicate the results of an operation by that program.
return indicator: An indicator to an RPG program that control should be returned to the calling program.
reverse charging: In X.25, a packet-switching data network optional facility that allows the data terminal equipment (DTE) to request that the cost of a communications session be charged to the DTE that is called.
reverse image: Text that appears on the display in the opposite color (for example, black on green instead of green on black).
reverse-interrupt character (RVI character): The BSC transmission control character that is sent as a request from the receiving station to the sending station to stop transmitting and begin receiving a message.
reverse map: To transform an Internet Protocol (IP) address to a host name as opposed to forward-mapping, where host names are transformed into IP addresses.
reverse mapping domain: A domain that transforms Internet Protocol (IP) addresses to host names.
revisable-form text (RFT): A data stream defined by document content architecture that is used to exchange unresolved documents (which cannot be directly printed or displayed) between systems. See also final-form text.
Revisable-Form-Text Document Content Architecture (RFTDCA): The architectural specification for the information interchange of documents whose text is in a revisable format. A Revisable-Form Text Document Content Architecture document consists of structured fields, controls, and graphic characters that represent the format and meaning of the document.
rewind: To move tape from the take-up hub to the supply hub.
REXX: See Restructured Extended Executor.
REXX/400: The i5/OS implementation of the Systems Application Architecture® Procedures Language. REXX/400 is a programming language that is supported by an interpreter provided as part of the i5/OS licensed program.
REXX/400 interpreter: The language processor of the i5/OS licensed program that processes procedures and programs written in the REXX language.
RFT: See revisable-form text.
RFTDCA: See Revisable-Form-Text Document Content Architecture.
RH: (1) See request header.; (2) See response header.
right justify: To print text with an even right margin by adding extra space throughout a line.
ring error monitor (REM): In communications, a function of the token-ring manager that observes, collects, and analyzes recoverable and irrecoverable error reports sent by token-ring stations on a single token-ring network and assists in fault isolation and correction.
RIO: See remote input/output.
RIP: See Router Information Protocol.
RISC: See reduced instruction set computer.
RJE: See SNA remote job entry.
RLE: See run-length encoding.
RLU: See report layout utility.
RMI: See Remote Method Invocation.
RMU: See resource management utility.
RNR: See receive not ready.
robot: For media library devices, a part (carriage and picker assembly) for moving media between the cartridge storage slots and the drives.
roll back: To remove changes that were made to database files under commitment control since the last commitment boundary. See also commitment boundary, commitment control.
rollback: The process of restoring data changed by an application program or user to the state at its last commitment boundary (commitment point).
rollback required (RBR): The rollback required logical unit of work (LUW) state indicates that a rollback vote was received for a prepare-for-commit request or that a failure has put the current transaction into a state where it must be rolled back. The transaction program is not allowed to perform any further changes under commitment control.
ROM: See read-only memory.
root directory: In the operating systems for personal computers, the directory on a disk or diskette that contains the list of files stored on that disk or diskette. If more than one directory is on a disk or diskette, the root directory is at the top of the hierarchy of directories. The root directory is created by the operating system when the disk or diskette is formatted.
root domain: Names servers that are authoritative for all of the top-level domains.
root file system: A file system that supports objects in the root (or /) directory. Access to all objects, regardless of which file system they actually reside in, starts at the root. Other file systems may be mounted over directories managed by the root file system, thus allowing all file systems to appear as a single file system tree.
root folder: The folder on the system that contains all other folders. The system-recognized identifier is *ROOT.
root group: In the Application Development Manager feature of the Application Development ToolSet licensed program, the first, or top, group in any project hierarchy.
root server: A name server that functions at the highest level node in the name system tree.
rotary dial: On a switched communications line, the dialing method that creates a series of pulses to identify the called station.
rotor: The rotating part of a sensor.
round-trip conversion: A conversion where the integrity of all character data is maintained from the source CCSID to the target CCSID and back to the source. The characters that are in both the target CCSID and the source CCSID are preserved. Any characters outside the target CCSID are arbitrarily assigned unique code points in the target CCSID.
route: The path that network traffic follows from its source to its destination.
route metrics: In Internet communications, the method used by the Routing Information Protocol (RIP) to choose the best Internet routes. The unit of measure is the number of hops between the origin and destination. In practice, the metric for a route is often assigned based on factors such as link transmission speed and line cost, not on the actual number of hops.
router: (1) A part of the iSeries Access licensed programs that handle requests to send and receive data from applications on the personal computer and routes them to the appropriate applications on the system.; (2) See gateway.; (3) A special purpose, dedicated computer that attaches two or more networks.
Router Information Protocol (RIP): The distance-vector routing protocol used by the Internetwork Packet Exchange (IPX) routers on the network to exchange routing information about the connected networks. The information is exchanged through the use of IPX. A RIP packet contains sets of network entry information.
routine: (1) In REXX, a series of instructions called with the CALL instruction or as a function. A routine can be either internal or external to a user's program.; (2) A set of statements in a program that causes the system to perform an operation or a series of related operations.
routine-name: In COBOL, a user-defined word that identifies a procedure written in a language other than COBOL.
routing: The list of users who are to receive an item when it is distributed, including all users named specifically and those users named on distribution lists by the sender.
routing data: Information stored in the job description that identifies the routing entry used by a job.
routing entry: An entry in a subsystem description that specifies the program to be called to control a routing step that runs in the subsystem.
routing step: The processing that results from running a program specified in a routing entry. Most jobs have only one routing step.
routing table: (1) In SNADS, a list of entries in a table that the system uses to route a message or electronic mail to a user on the system. Each entry is made up of a destination group name (such as a department or organization) and a destination element name (the user ID of each person in that department or organization).; (2) In a point-to-point profile, a collection of path information through which hosts or networks can communicate with other hosts and networks.
row: The horizontal component of a table consisting of a sequence of values, one for each column of the table.
RPC: See remote procedure call.
RPG: See Report Program Generator.
RPQ: See request for price quotation.
RR: (1) See receive ready.; (2) See resource record.
RS-310: An Electronic Industries Association standard for designing racks to hold data processing equipment.
RST: See reset.
RTAM: See remote terminal access method.
RTS: See reliable transfer server.
RU: (1) See request unit.; (2) See response unit.
RU chain: In SNA, a set of related request or response units that are transmitted consecutively on a particular normal or expedited data flow.
rule: A procedure that defines how Internet Protocol (IP) packet security should handle packets. Rules in IP packet security pertain to hidden addresses, mapped addresses, and filters.
rules file: A file that contains rules and definitions that pertain to those rules.
RUMBA/400: An optionally installable component of iSeries Access, based on the Microsoft® Windows® program, that provides 5250 display emulation and 5225 printer emulation.
run-length encoding (RLE): A technique for compressing data that avoids repeatedly having to code data elements of the same value; instead, the value is coded once, along with the number of times for it to be repeated.
run time: The time period during which a computer program is running.
runtime array: In RPG, an array that is loaded or created by input or calculation specifications after the program starts to run. See also compile-time array, preruntime array.
runtime defaults: In query management, all of the formatting elements of a formatted report that were not explicitly specified in the form.
runtime environment: In the C language, a logical grouping of one or more program objects that must be connected at application run time to do some task.
runtime table: In RPG, a table that is loaded or created by input or calculation specifications after the program starts to run. See also compile-time table, preruntime table.
run unit: In COBOL, a set of one or more programs that run as a set to solve a problem. A set starts with the first COBOL program in the call stack and includes all programs (COBOL) (non-COBOL) that are below it in the call stack.
RUOW: See remote unit of work.
RVI character: See reverse-interrupt character.
RVX: The Electronic Industries Association (EIA) RS standards (for example, RS-232); the ITU/CCITT standards (for example, V.24 for modem interconnects and protocols); and the ITU/CCITT standards for interconnects and protocols (for example X.21). ITU is the International Telecommunications Union, and CCITT is the International Consulting Committee for Telephony and Telegraphy.