Glossary

This Glossary contains the definitions of some of the important terms and concepts used in the UDS/SQL manuals.
Terms that appear in italics within a particular definition have also been defined in this Glossary.
In cases where two or more terms are used synonymously, a “See” reference points to the more commonly used term in these manuals.

A
	access, contending
		See contending access.
	access, direct
		See direct access.
	access, sequential
		See sequential access.
	access authorization
		The rights of a specified user group with regard to access to the database . Access rights are defined during live database operation using ONLINE- PRIVACY utility routine or, in offline mode, using the BPRIVACY utility routine.
	access path
		Means of finding a certain subset of all records qualified by a search query, without having to carry out a sequential search of the whole database.
	access rights
		Right of access to a database as defined in the BPRIVACY utility routine.
	access type
		Type of access, e.g. read, update etc.
	act-key
		(actual key) Actual address of a page, consisting of realm number and page number.
	act-key-0 page
		First page of a realm; contains general information on the realm such as when the realm was created, when the realm was last updated, internal version number of the realm, system break information if applicable, warm start information.
	act-key-N page
		Characteristic page of a realm, with the highest page number. Copy of the act-key-0 page.
	address, physical
		See act-key or probable position pointer (PPP).
	administrator task
		Task of the independent DBH; The database administrator can control execution of the independent DBH via this task.
	AFIM
		See after-image.
	after-image
		Modified portion of a page after its content has been updated. The DBH writes after-images to the RLOG file as well as the ALOG file.
	after-image, ALOG file
		The after-images are written to the ALOG file when the ALOG buffer is full. The purpose of the after-images in the ALOG file is to secure the data contained in the database and thus they must be maintained for a long period of time. They are used to reconstruct an original database or update a shadow database.
	after-image, RLOG file
		After-images are logged in the RLOG file before the updates are applied to the database. The after-images held in the RLOG file are required for warm start only. They are thus periodically overwritten.
	ALOG file
		File for securing the data contained in the database in the long term; see after-image.
	ALOG sequence number
		See sequence number.
	anchor record
		Record automatically created by UDS/SQL as owner record for SYSTEM sets. It cannot contain any items defined with the schema DDL and cannot be accessed.
	application
		Realization of a job in one or several user programs working with UDS/SQL databases.
	application program (AP)
		E.g. COBOL DML program or IQS.
	area
		See realm.
	ascending key (ASC key)
		Primary key of a set. Defines the sequence of member records in the set occurrences by ascending key values.
	authorization
		Identification used for user groups.
	authorized users
		Specified user groups who are authorized to access the database.
	automatic DBTT extension
		Some utility routines automatically extend the number of records possible for a record type if too few are available; no separate administration is required to do this. See also online DBTT extension.
	automatic realm extension
		Some utility routines automatically extend realms when insufficient free space is available; no separate administration is required to do this. See also online realm extension.
B
	backup database
		See shadow database.
	base interface block (BIB)
		(Base Interface Block) Standard interface between UDS/SQL and each individual user; it contains, among other things, the RECORD AREA (user records as defined in the subschema).
	before-image
		Copy of a page taken before its contents are updated. The DBH writes before-images to the RLOG files during database operation before the updates are applied to the database. A prerequisite is that the RLOG files exist.
	BFIM
		See before-image.
	BIB
		See base interface block.
	buffer pool
		See system buffer pools and exclusive buffer pool.
C
	CALC key
		Key whose value is converted into a relative page number by means of a hash routine.
	CALC page
		Page of a hash area.
	CALC SEARCH key
		Secondary key. Used as access path for direct access via hash routine.
	CALC table
		Table in the direct/indirect CALC page whose entries point to the stored records. Each line contains: the CALC key, the record sequence number the displacement to the related page index entry (direct CALC page) or the probable position pointer (indirect CALC page).
	CALL DML
		DML that is called by various programming languages (Assembler, COBOL, FORTRAN, PASCAL, PL/1) via the CALL interface.
	catalog identifier
		Name of the public volume set (PVS) under which the BS2000 UDS/SQL files are stored. The catalog identifier is part of the database or file name and must be enclosed in colons: “:catid:”.
	chain
		Storage mode for a set occurrence in which every record contains a pointer to the subsequent record.
	Character Separated Values (CSV)
		Output format in which the values are separated by a predefined character.
	checkpoint
		Consistency point , at which the ALOG file was changed and to which it is possible to return at any time using BMEND utility routine.
	check records
		Elements which provide information for checking the database. They vary in length from 20 to 271 bytes.
	CHECK-TABLE
		Check table produced by the DDL  compiler during Subschema DDL compilation, and used by the COBOL compiler and  CALL DML to check whether the DML  statements specified in the  application program are permitted. It is part of the COSSD  or  SSITAB module .
	clone pair, clone pubset, clone session, clone unit
		A clone unit is the copy of an (original) unit (logical disk in BS2000) at a particular time (“Point-in-Time copy”). The TimeFinder/Clone component creates this copy optionally as a complete copy or as a “snapshot”. After they have been activated, the unit and clone unit are split; applications can access both. The unit and clone unit together form a clone pair. TimeFinder/Clone manages this pair in what is known as a clone session. If clone units exist for all units of a pubset, these clone units together form the clone pubset. Details of this are provided in the manual "Introduction to System Administration" .
	COBOL DML
		DML  integrated in the COBOL language.
	COBOL runtime system
		Runtime system; sharable routines selected by the COBOL compiler (COBOL2000 or COBOL85) for the execution of complex statements.
	COBOL Subschema Directory (COSSD)
		Provides the COBOL compiler with subschema information for compilation of the DB application programs .
	common memory
		Shareable memory area used by several different tasks. In UDS/SQL, it always consists of the common pool  and the  communication pool  and, depending on the application, the SSITAB pool (see  SSITAB module ) if CALL DML is used. If UDS-D is used, it also consists of the distribution pool  and the transfer pool .
	common pool
		Communication area of the independent DBH . Enables DBH  modules to communicate with each other. Contains, among other things, an input/output buffer for pages  ( buffer pools ).
	communication partners
		Tasks or data display terminals.
	communication pool
		Communication area of the independent DBH  for application programs . One of its functions is to store base interface blocks ( BIB ).
	compatible database interface (KDBS)
		see KDBS.
	compiler database
		The realms and files of the database which are required by the UDS/SQL compiler. They are DBDIR (Database Directory) DBCOM (Database Compiler Realm) COSSD (COBOL Subschema Directory).
	COMPILER-SCHEMA
		UDS/SQL-internal schema of the compiler database.
	COMPILER-SUBSCHEMA
		UDS/SQL-internal subschema of the compiler database.
	compound key
		Key consisting of several key items.
	compression
		Only the filled items of a record are stored (see SSL clause COMPRESSION).
	configuration
		See DB configuration.
	configuration user ID
		User ID in which the database administrator starts the DBH.
	configuration name
		Freely selectable name of the database configuration for a particular session. The DBH uses it to form: the name of the Session Log File, the names of the DB status file and its backup copy, the names of the RLOG files, the names of the temporary realms, the names of session job variables, the event names of P1 eventing, the DCAM application name for the administration, the names of the common pools the names of the dump files.
	connection module
		Module that must be linked into every UDS/SQL application program and which establishes the connection with the DBH.
	consistency
		State of the database without conflicts in the data stored in it.
	consistency, logical
		State of the database in which the stored data has no internal conflicts and reflects the real-world situation.
	consistency, physical
	State of the database in which the stored data is consistent with regard to correct physical storage, access paths and description information.
consistency, storage
	See physical consistency.
consistency error
	A violation of the physical consistency of the stored data.
consistency point
	Point (in time) at which the database is consistent, i.e. all modifying transaction have been terminated and their modifications have been executed in the database.
consistency record
	Administration record with consistency time and date stamps in the DBDIR. For an update in a realm the DBH enters the date and time in the consistency record and in the updated realm. When realms or databases are attached for a session, the DBH uses this time stamp to check the consistency of the realms within each database.
contending access
	Different transactions attempting to access a page simultaneously.
conversation
	SQL -specific administration data is retained across transaction boundaries in an SQL application. This kind of data administration unit is called a conversation. In openUTM such an administrative unit is also called a service.
copy
	See database copy.
COSSD
	See COBOL Subschema Directory.
CRA
	(Current Record of Area) Record which is marked in the currency table as the current record of a particular realm (area).
CRR
	(Current Record of Record) Record which is marked in the currency table as the current record of a particular record type (Record) .
CRS
	(Current Record of Set) Record which is marked in the currency table as the current record of a particular set.
CRU
	(Current Record of Rununit) Record which is marked in the currency table as the current record of the processing chain.
CSV
	see Character Separated Values.
currency table
	The currency table contains: CURRENT OF AREA table (table of CRAs), CURRENT OF RECORD table (table of CRRs) and CURRENT OF SET table (table of CRSs).
CURRENT OF AREA table
	See currency table.
CURRENT OF RECORD table
	See currency table.
CURRENT OF SET table
	See currency table.
D
	DAL
		(Database Administrator Language) Comprises the commands which monitor and control a session.
	data backup
		Protection against loss of data as a result of hardware or software failure.
	data deadlock
		See deadlock.
	data protection (privacy)
		Protection against unauthorized access to data. Implemented in UDS/SQL by means of the schema/subschema concept and access authorization. Access rights are granted by means of the BPRIVACY utility routine.
	database (DB)
		Related data resources that are evaluated, processed and administered with the help of a database system. A database is identified by the database name. An UDS/SQL database consists of the user database and the compiler database. To prevent the loss of data, a shadow database may be operated together with (i.e. parallel to) the original database.
	database administrator
		Person who manages and controls database operation. The DB administrator is responsible for the utility routines and the Database Administrator Language (DAL).
	database copy
		Copy of a consistent database; may be taken at a freely selectable point in time.
	database compiler realm (DBCOM)
		Stores information on the realms, records and sets defined by the user in the Schema DDL and Subschema DDL.
	database copy update
		Updating of a database copy to the status of a checkpoint by applying the appropriate after-images.
	database directory (DBDIR)
		Contains, among other things, the SIA, all the SSIAs and information on access rights.
	database job variable
		Job variable in which UDS/SQL stores information on the status of a database.
	database key (DB key)
		Key whose value represents a unique identifier of a record in the database. It consists of the record reference number and the record sequence number. The database key values are either defined by the database programmer or automatically assigned by UDS/SQL.
	database key item
		Item of type DATABASE-KEY or DATABASE-KEY-LONG that is used to accommodate database key values. Items of type DATABASE-KEY and DATABASE-KEY-LONG differ in terms of the item length (4 bytes / 8 bytes) and value range.
	DATABASE-KEY item
		See database key item.
	DATABASE-KEY-LONG item
		See database key item.
	database page
		See page.
	DATABASE-STATUS
		Five-byte item indicating the database status and consisting of the statement code and the status code.
	database system
		Software system that supports all tasks in connection with managing and controlling large data resources. The database system provides mechanisms for stable and expandable data organization without redundancies. They allow many users to access databases concurrently and guarantee a consistent data repository.
	DB status file
		(database status file) Contains information on the most recently reset transactions. openUTM-S or, in the case of distributed processing, UDS-D/openUTM-D needs this information for a session restart.
	DB configuration
		(database configuration) The databases attached to a DBH at any one point during session runtime. As the result of DAL commands or DBH error handling, the database configuration can change in the course of a session. At the session start, the DB configuration may be empty. Databases can be attached with DAL commands after the start of the session. They can also be detached during the session with DAL commands.
	DBCOM
		See database compiler realm.
	DBDIR
		See database directory.
	DBH
		Database Handler: program (or group of programs) which controls access to the database(s) of a session and assumes all the attendant administrative functions.
	DBH end
		End of the DBH program run. DBH end can be either a session end or a session abort.
	DBH, independent
		See independent DBH.
	DB key
		See database key.
	DBH, linked-in
		See linked-in DBH.
	DBH load parameters
		See load parameters (DBH).
	DBH start
		Start of the DBH program run. DBH start can be either a session start or a session restart.
	DBTT
		(Database Key Translation Table) Table from which UDS/SQL can obtain the page address (act-key) of a record and associated tables by means of the database key value. The DBTT for the SSIA-RECORD consists only of the DBTT base. For all other record types, the DBTT consists of a base table (DBTT base) and possibly of one or more extension tables (DBTT extents) resulting from an online DBTT extension or created by BREORG.
	DBTT anchor page
		Page lying within the realm of the associated DBTT in which the DBTT base and DBTT extents are administered. Depending on the number of DBTT extents multiple chained DBTT anchor pages may be required for their administration.
	DBTT base
	see DBTT
DBTT extent
	see DBTT
DBTT page
	Page containing the DBTT or part of the DBTT for a particular record type.
DCAM
	Component of the TRANSDATA data communication program.
DCAM application
	Communication application using the DCAM communication method. A DCAM application enables communication between a DCAM application and terminals. different DCAM applications within the same or different hosts, and with remote  configurations. a DCAM and a openUTM application.
DDL
	(Data Description Language) Formalized language for defining the logical data structure.
deadlock
	Mutual blocking of transactions. A deadlock can occur in the following situations: Data deadlock: This occurs when transactions block each other with contending access. Task deadlock: This occurs when a transaction that is holding a lock cannot release it, since no openUTM task is free. This deadlock situation can only occur with UDS/SQL-openUTM interoperation.
descending key (DESC key)
	Primary key of a set. Determines the sequence of member records in the set occurrences to reflect descending key values.
direct access
	Access to a record via an item content. UDS/SQL supports direct access via the database key, hash routines and multi-level tables.
direct hash area
	See hash area.
distributed database
	A logically connected set of data resources that is distributed over more than one UDS/SQL configuration.
distributed transaction
	Transaction that addresses at least one remote configuration. A transaction can be distributed over: UDS-D, openUTM-D, UDS-D and openUTM-D.
distribution pool
	Area in the independent DBH used for communication between UDSCT, server tasks, user tasks and the master task with regard to UDS-D-specific data. The distribution pool contains the distribution table and the UDS-D-specific system tables.
distribution table
	Table created by UDS-D using the input file assigned in the distribution pool. With the aid of the distribution table, the distribution component in the user task decides whether a processing chain should be processed locally or remotely. Assigned in the distribution table are: subschema - database database - configuration configuration - host computer.
DML
	Data Manipulation Language: language for accessing a UDS/SQL database.
dummy subtransaction
	A primary subtransaction  is created by UDS-D when the first  READY  statement in a  transaction  addresses a  remote database . A dummy subtransaction is used to inform the  local configuration  of the transaction so that the  database  can be recovered following an error.
duplicates header
	Contains general information on a duplicates table or a page of a duplicates table, i.e. chaining reference to the next and previous overflow page the number of free bytes in the page of the duplicates table.
duplicates table
	Special SEARCH-KEY table in which a key value which occurs more than once is stored only once. For each key value, the duplicates table contains: a table index entry with the key value and a pointer to the associated table entry a table entry (DB key list), which can extend over several pages, containing the record sequence numbers of the records which contain this key value.
duplicates table, main level
	Main level, Level 0. Contains a table index entry and the beginning of the associated table entry (DB key list).
dynamic set
	Set which exists only for the life of a transaction and which stores member records retrieved as result of search queries.
E
	ESTIMATE-REPORT
		Report produced after BGSIA run. Used to estimate the size of the user realms.
	event name
		Identification used in eventing.
	exclusive buffer pool
		Buffer which, in addition to the system buffer pools, is used exclusively for buffering pages of the specified database.
F
	foreign key
		Record element whose value matches the primary key values of another table (UDS/SQL record type). Foreign keys in the sense of UDS/SQL are qualified as "REFERENCES owner record type" in the member record type of a set relationship in the BPSQLSIA protocol.
	FPA
		See free place administration.
	FPA base
		See free place administration.
	FPA extent
		See free place administration.
	FPA page
		Free place administration page.
	free place administration (FPA)
		Free space is managed both at realm level (FPA pages) and at page and table level. Free place administration of the pages is carried out in a base table (FPA base) and possibly in one or more extension tables (FPA extents) created by means of an online realm extension or BREORG.
	function code
		Coding of a DML statement; included in information output by means of the DAL command DISPLAY or by UDSMON.
G
	group item
		Nameable grouping of record elements.
H
	hash area
		Storage area in which UDS/SQL stores data and from which it retrieves data on the basis of key values which are converted into relative page numbers. A hash area may contain the record addresses as well as the records themselves. A direct hash area contains the records themselves; an indirect hash area, by contrast, contains the addresses of records stored at some other location.
	hash routine
		Module which performs hashing.
	hashing
		Method of converting a key value into a page address.
	HASHLIB
		Module library for the storage of hash routines for one database.
I
	identifier
		Name allocated by the database designer to an item that UDS/SQL creates automatically. UDS/SQL adapts item type and length to the specified item usage.
	implicit set
		SYSTEM set created by UDS/SQL when a SEARCH key is defined at record type level.
	inconsistency
		State of the database in which the data values contained in it are inconsistent.
	independent DBH
		Independent program system enabling more than one user to access a single database (mono-DB operation) or several databases (multi-DB operation) simultaneously. The independent DBH is designed as a task family, consisting of a master task (UDSSQL) one or more server tasks (UDSSUB) an administrator task (UDSADM)
	index level
		Hierarchy level of an index page.
	index page
		Page in which the highest (lowest) key values of the next-lower level of an indexed table are stored.
	INDEX search key
		Secondary key. Used as access path for direct access via a multi-level table.
	indirect hash area
		See hash area.
	integrity
		State of the database in which the data contained in it is complete and free of errors. entity integrity referential integrity user integrity
	interconfiguration
		Concerning at least one remote configuration.
	interconfiguration consistency
		A distributed transaction that has caused updates in at least one remote configuration is terminated in such a way that the updates are either executed on the databases in each participating DB configuration or on none at all. Interconfiguration consistency is assured by the two-phase commit protocol.
	interconfiguration deadlock
		Situation where distributed transactions are mutually locked due to contending accesses.
	interface
		In software: memory area used by several different programs for the transfer of data.
	internal version number
		Each realm of the database, including DBDIR and DBCOM, has an internal version number which the utility routines (e.g. BREORG, BALTER) increment by one whenever a realm is updated. This internal version number is kept in the act-key-0 page of the realm itself and also in the PHYS VERSION RECORD in the DBDIR.
	item
		Smallest nameable unit of data within a record type. It is defined by item type and item length.
K
	KDBS
		Compatible database interface. Enables programs to be applied to applications of DB systems by different manufacturers.
	key
		Item used by the database programmer for direct access to records; an optimized access path is provided for the key by UDS/SQL in accordance with the schema definition.
	key, compound
		Key consisting of several key items.
	key item
		Item defined as a key in the schema.
	key reference number
		Keys are numbered consecutively in ascending order, beginning at 1.
L
	linked-in control system
		UDS/SQL component for linked-in DBH, responsible for control functions (corresponds to the subcontrol system of the independent DBH).
	linked-in DBH
		Module linked in to or dynamically loaded for the current DB application program and controlling access to a single database (mono-DB operation) or several databases simultaneously (multi-DB operation).
	list
		Table containing the member records of a set occurrence. Used for sequential and direct access to member records. In a distributable list the data pages which contain the member records (level 0 pages) can be distributed over more than one realm. The pages containing the higher-ranking table levels all reside in one realm (table realm of a distributable list).
	load parameters (DBH)
		Parameters requested by the DBH at the beginning of the session. They define the basic characteristics of a session.
	local application program
		An application program is local with regard to a configuration if it was linked to the configuration using /SET-FILE-LINK LINK-NAME=DATABASE,FILENAME=conf-name
	local configuration
		The configuration assigned to an application program before it is called using /SET-FILE-LINK LINK-NAME=DATABASE,FILE-NAME=conf-name The application program communicates with the local configuration via the communication pool. The local configuration is in the same host as the application program.
	local database
		Database in a local configuration.
	local distribution table
		A distribution table is considered local to a DBH if it is held in the DBH’s distribution pool.
	local host
		Host computer containing the application program.
	local transaction
		Transaction that only addresses the local configuration.
	logging
		Recording of all updates in the database.
	logical connection
		Assignment of two communication partners that enables them to exchange data. DCAM applications communicate via logical connections.
M
	main reference
		In the DBH the main reference is used to manage the resources required for processing a transaction’s requests, including those for transferring the requests from the application program to the DBH and back.
	mainref number
		Number assigned to the transaction at READY. This number is unique only at a given time; at the end of the transaction, it is assigned to another transaction.
	master task
		Task of the independent DBH in which the UDSQL module executes. Controls the start and end of a session and communicates with the database administrator directly or via the administrator task.
	member
		See member record or member record type.
	member, AUTOMATIC
		Record is inserted at storage time.
	member, MANDATORY
		Record cannot be removed.
	member, MANUAL
		Record is not inserted automatically at storage time.
	member, OPTIONAL
		Record can be removed.
	member record
		Lower-ranking record in a set occurrence.
	member record type
		Lower-ranking record type in a set.
	mono-DB configuration
		Type of configuration where only one database takes part in a session.
	mono-DB operation
		Mode of database operation where the DBH uses only one database of a configuration.
	multi-DB configuration
		Type of configuration where several databases take part in a session.
	multi-DB operation
		Mode of database operation where the DBH uses several databases of a configuration.
	multi-DB program
		Application program that addresses more than one database. The databases may be part of one or more mono-DB or multi-DB configurations.
	multi-level table
		SEARCH KEY table which contains a line for each record of the associated record type or each member record of the set occurrence, as appropriate. Each line comprises the key value of the record and the record pointer. It is also referred to as an indexed table.
	multithreading
		A mechanism that enables the DBH to fully exploit the CPU. Multithreading means that the DBH processes several jobs concurrently by using so-called threads. Each thread has information on the current status of a particular job stored in it. When a job needs to wait for the completion of an I/O operation, DBH uses the CPU to process some other job.
N
	network
		All computers linked via TRANSDATA.
O
	OLTP
		(Online Transaction Processing) In an OLTP application, a very large number of users access the same programs and data. This usually occurs under the control of a transaction monitor (TP monitor).
	online backup
		If AFIM logging is active, the database can be saved during a session. The ability to save a database online is determined with the BMEND utility routine.
	online DBTT extension
		Extension during ongoing database operation of the number of possible records of a record type. The DAL commands ACT DBTT-INCR, DEACT DBTT-INCR, DISPLAY DBTT-INCR and EXTEND DBTT can be used to administer the online extension of DBTTs. See also automatic DBTT extension.
	online realm extension
		Extension of user realms and DBDIR in ongoing database operation. The DAL commands ACT INCR, DEACT INCR, DISPLAY INCR, EXTEND REALM and REACT INCR are provided for administering the online extensibility of realms. See also automatic realm extension.
	open transaction
		Transaction which has not been closed with FINISH or FINISH WITH CANCEL, or with COMMIT or ROLLBACK.
	openUTM
		(universal transaction monitor) Facilitates the creation and operation of transaction-oriented applications.
	operator task (OT)
		See master task
	original database
		The term “original database” refers solely to the naming of the database files (dbname.dbfile), not to the status of the database content (see also shadow database).
	overflow page
		Page in hash areas and duplicates tables for storing data that does not fit in the primary page. Their structure is the same as that of the pages of the hash area or duplicates table in question.
	owner
		See owner record or owner record type.
	owner record
		Higher-ranking record in a set occurrence.
	owner record type
		Higher-ranking record type in a set.
P
	page
		Physical subunit of a realm. UDS/SQL identifies pages by means of unique keys (act-key). The length of a page may be optionally 2048, 4000 or 8096 bytes. All pages within a database must have the same length. Pages with a length of 4000 or 8096 bytes are embedded in a page container.
	page address
		In a page address, a distinction is made between the current address of a page, i.e. the act-key, and the probable address of a page, the probable position pointer (PPP).
	page container
		Pages with a length of 4000 or 8096 bytes are embedded in a so-called page container, which consists of a 64-byte header that precedes the page and a 32-byte trailer at the end of the page.
	page header (page info)
		The first 20 bytes of a database page (except for the FPA and DBTT pages with a length of 2048 bytes). They contain: the act-key of the page itself, the number of page index entries the length and displacement of the bytes which are still vacant in this page. the page type (ACT-Key-0 page, FPA page, DBTT page, DBTT anchor page, normal data page or CALC page)
	page index entry
		Indicates the position of a record within a page.
	page number
		In each realm the pages are numbered consecutively in ascending order starting starting from 0. The page number is part of the page address. Page number = PAM page number -1 for databases with a page length of 2048 bytes Page number = (PAM page number-1) / 2 for databases with a page length of 4000 bytes Page number = (PAM page number-1) / 4 for databases with a page length of 8096 bytes.
	password for UDS/SQL files
		Password serving to protect the files created by UDS/SQL (default: C’UDS'BLANK'’). The DB administrator can define other passwords with PP CATPASS or MODIFY-FILE-ATTRIBUTES.
	pattern
		Symbolic representation of all possible item contents, used at item definition.
	pattern string
		String defining a pattern.
	PETA
		Preliminary end of transaction: UDS-D or openUTM-D statement that causes a preliminary transaction end. The PETA statement belongs to the first phase of the two-phase commit protocol which terminates a distributed transaction. The PETA statement stores the following information failproof in the RLOG file of the local DBH: each updated page rollback and locking information the names of all participating configurations. This information is required for any future warm start.
	pointer array
		Table of pointers to the member records of a set occurrence. Used for sequential and direct access to member records.
	PPP
		See probable position pointer (PPP).
	prepared to commit (PTC)
		Part of the two-phase commit protocol: State of a subtransaction after execution of a PETA statement and before receipt of the message that the complete transaction is to be terminated with FINISH or FINISH WITH CANCEL.
	primary key
		Distinguished from secondary keys for reasons of efficiency. Usually a unique identifier for a record.
	primary key (DDL)
		The key of a record type which is defined by means of "LOCATION MODE IS CALC" or the key of an order-determining key of a set occurrence which is defined by means of "ORDER IS SORTED [ INDEXED]". Also used for direct access to a record or a set of records with the same key values or within a search interval.
	primary key (SQL)
		In the broader sense (SQL), a record element uniquely identifying a record. In UDS-SQL, the database key of an owner record output as the "PRIMARY KEY" in the BPSQLSIA log (see also foreign key). A record element which uniquely identifies a record is flagged as "UNIQUE" in the BPSQLSIA log unless it is the aforementioned "PRIMARY KEY".
	primary subtransaction
		Subtransaction that runs in the local configuration. The primary subtransaction is opened by the first READY statement in a transaction on a local database. If the first READY statement addresses a remote database, UDS-D generates a dummy subtransaction as the primary subtransaction.
	PRIVACY-AND-IQF SCHEMA
		UDS/SQL-internal schema for protection against unauthorized access.
	PRIVACY-AND-IQF SUBSCHEMA
		UDS/SQL-internal subschema for protection against unauthorized access.
	probable position pointer (PPP)
		Probable address of a page, comprising realm number and page number. UDS/SQL does not always update probable position pointers (PPP) when the storage location of data is changed.
	processing chain
		Sequence of DML statements applied to a database within a transaction.
	PTC state
		See prepared to commit.
	pubset declaration
		Siee UDS/SQL pubset declaration
	pubset declaration job variable
		Job variable in which a UDS/SQL pubset declaration is specified.
	P1 eventing
		Manner in which tasks communicate with each other.
R
	READY
		Start of a transaction or a processing chain in COBOL DML programs.
	READYC
		Start of a transaction or a processing chain in CALL DML programs.
	realm
		Nameable physical subunit of the database. Equivalent to a file. Apart from the user realms for user data there are also the realms DBDIR and DBCOM, which are required by UDS/SQL.
	realm configuration
		Comprises all the database realms taking part in a session.
	realm copy
		See database copy.
	realm reference number
		Realms are numbered consecutively in ascending order, starting with 1. The realm reference number (area reference) is part of the page address.
	reconfiguration
		Regrouping of databases in a DB configuration after a session abort. A prerequisite for reconfiguration is that the SLF has been deleted or that its contents have been marked as invalid.
	record
		Single occurrence of a record type; consists of one item content for each of the items defined for the record type and is the smallest unit of data managed by UDS/SQL via a unique identifier, the database key. The reserved word RECORD is used in DDL and SSL syntax to declare a record type.
	record address
		Address of the page containing the record. See page address.
	RECORD AREA
		Area in the USER WORK AREA (UWA) which can be referenced by the user. The record area contains the record types and the implicitly defined items (IMPLICITLY-DEFINED-DATA-NAMES) of the database such as the AREA-ID items of the WITHIN clauses of the schema. The length of the record area is essentially defined by the record types contained in it.
	record element
		Item, vector or group item.
	record hierarchy
		Owner/member relationship between record types: the owner record type is the higher-ranking part of the relationship; the member record type is the lower-ranking part.
	REC-REF
		See record reference number.
	record reference number
		Record types are numbered consecutively in ascending order, starting at 1. The record reference number is part of the database key.
	record SEARCH KEY table
		SEARCH KEY table for selection of a record from a record type.
	record sequence number (RSQ)
		The record sequence number can be assigned by the database programmer; if not, UDS/SQL numbers the records of a record type contiguously in ascending order, in the sequence in which they are stored; numbering starts at 1. The record sequence number is part of the database key.
	record type
		Nameable grouping of record elements.
	record type, linear
		Record type that is neither the owner nor the member of a set (corresponds to record types of a conventional file).
	referential integrity
		Integrity of the relationships between tables (UDS/SQL record types).
	remote application program
		Application program that is not local with regard to a particular configuration.
	remote configuration
		DB-configurations that are not assigned to the application program via /SET-FILE-LINK LINK-NAME=DATABASE,FILE-NAME=conf-name but via the distribution table once the application program is running. The connection module of the application program communicates with the remote configurations via DCAM applications. Remote configurations can be situated on local or remote hosts.
	remote database
		Database in a remote configuration.
	remote host
		Host computer that is not local.
	repeating group
		Group item with repetition factor. The repetition factor, which must be greater than 1, specifies the number of duplicates of the group item to be incorporated in the repeating group.
	request
		The functions of the DAL commands ADD DB, ADD RN, DROP DB, DROP RN, NEW RLOG and CHECKPOINT are held in the DBH as "requests" and are not executed until the DAL command PERFORM is entered.
	restart of BMEND
		Resumption of an aborted BMEND run.
	restart of a session
		See session restart.
	restructuring
		Modification of the Schema DDL or SSL for databases already containing data.
	return code
		Internal code which the called program sends to the calling program; Return code != 0 means an error has occurred.
	RLOG file
		Backup file used by the DBH during a session to store before-images (BFIMs) and after-images (AFIMs) of data which is updated. With the aid of the RLOG file, the DBH can cancel updates effected by incomplete transactions. There is one RLOG file per configuration. An RLOG file consists of two physical files.
	rollback
		Canceling of all updates effected within a transaction.
	RSQ
		See record sequence number.
	RUNUNIT-ID
		See transaction identification.
S
	schema
		Formalized description of all data structures permitted in the database. A UDS/SQL schema is defined by means of the Schema DDL.
	Schema DDL
		Formalized language for defining a schema.
	Schema Information Area (SIA)
		The SIA contains the complete database definition. The DBH loads the SIA into main memory at the start of DB processing.
	SEARCH KEY
		Secondary key; access paths using secondary keys are created by UDS/SQL by means of hash routines and multi-level tables.
	SEARCH KEY table
		Multi-level table used by UDS/SQL as an access path via a secondary key.
	secondary key
		Any key which is not a primary key. Used for direct access to a record or a set of records with the same key values or within a search interval.
	secondary subtransactions
		Subtransactions that address remote configurations.
	sequence number
		Identifier in the name of the ALOG files (000000001 - 999999999). The first ALOG file of a database is always numbered 000000001.
	sequential access
		Accessing a record on the basis of its position within a predefined record sequence.
	server task
		Task of the independent DBH in which the UDSSUB module executes; processes the requests of the DB application programs.
	session
		Period between starting and normal termination of the DBH (independent / linked- in) in which it is possible to work with the databases of the configuration. Normally, a session consists of a sequence of session sections and session interrupts.
	session abort
		Occurs when the DBH is terminated abnormally after a successful session start. A session abort can be caused by: power failure, computer failure, BS2000 problems, DBH problems, %TERM.
	session end
		Is the result of: DAL when using independent DBH, TERM in the DML application program when using linked-in DBH, DBH error handling. During a session interrupt, the user can also effect session end by invalidating the SLF contents. Inconsistent databases can be made consistent again by a warm start, even without an SLF.
	session interrupt
		The period between a session abort and the related session restart.
	session job variable
		Job variable in which UDS/SQL stores information about a session.
	Session Log File (SLF)
		File which is permanently assigned to a session and which is required by the DBH in the event of a session restart. It contains information on the current DB configuration, the number of current file identifiers and the current values of the DBH load parameters.
	session restart
		Starting of the DBH, under the same configuration name and configuration user ID, after a session abort. With the aid of the SLF, the DBH load parameters and the current file identifiers which existed when the session aborted are re-established, and the databases of the previous configuration are reattached, if necessary by means of a warm start.
	session section
		Period from the start of the DBH, either at the session start or a restart, to the normal session end or to a session abort.
	session section number
		Number which identifies a session section unambiguously.
	session start
		State of a session in which the DBH is started under a configuration name for which there is no Session Log File (SLF) with valid contents.
	set
		Nameable relationship between two record types.
	set, dynamic
		See dynamic set.
	set, implicit
		See implicit set.
	set, singular
		See SYSTEM set.
	set, standard
		See standard set.
	Set Connection Data (SCD)
		Linkage information for the records of a set occurrence.
	set occurrence
		Single instance of a set. Comprises exactly one owner record and any number of subordinate member records.
	set reference number
		Sets are numbered contiguously in ascending order, beginning at 1.
	set SEARCH KEY table
		SEARCH KEY table for selecting a member record from a set occurrence.
	SF pubset
		See single feature pubset
	shadow database
		Backup of all the files of a database, each saved under the name ”dbname.dbfile.copyname”. A shadow database can be created at any time and processed parallel to the original database in RETRIEVAL mode. In addition BMEND can be used to apply ALOG files that have already been closed to the database parallel to the UDS/SQL session.
	Shared user buffer pool
		Shared buffer of several databases which is used in addition to the System Buffer Pool, solely for buffering pages of the databases that have been assigned to it.
	SIA
		See Schema Information Area.
	SIB
		See SQL Interface Block.
	single feature pubset
		A single feature pubset (SF pubset) consists of one or more homogeneous disks which must have the same major properties (disk format, allocation unit).
	SLF
		See session log file.
	SM pubset
		See system managed pubset
	snap pair, snap pubset, snap session, snap unit
		A snap unit is the copy of an (original) unit (logical disk in BS2000) at a particular time (“Point-in-Time copy”). The TimeFinder/Snap component creates this copy as a “snapshot” in accordance with the “Copy-On-First-Write strategy“: Only if data is modified is the original data concerned written beforehand into a central save pool of the Symmetrix system. The snap unit contains the references (track pointers) to the original data. In the case of unmodified data the references point to the unit, in the case of modified data to the save pool. After they have been activated, the unit and snap unit are split; applications can access both. The unit and snap unit together form a snap pair. TimeFinder/Snap manages this pair in what is known as a snap session.If snap units exist for all units of a pubset, these snap units together form the snap pubset. Details of this are provided in the manual "Introduction to System Administration".
	sort key table
		Table pointing to the member records of a set occurrence.
	source program
		Program written in a programming language and not yet translated into machine language.
	spanned record
		Record exceeding the length of a page. Only UDS/SQL-internal records can be spanned records; User record types must not exceed 2020 bytes for a page length of 2048 bytes 3968 bytes for a page length of 4000 bytes 8064 bytes for a page length of 8096 bytes.
	SQL
		SQL is a relational database language which has been standardized by ISO (International Organization for Standardization).
	SQL conversation
		See conversation.
	SQL DML
		SQL Data Manipulation Language for querying and updating data.
	SQL Interface Block (SIB)
		Interface between UDS/SQL and SQL application program(s); contains the SQL statement, any existing parameters and the statement results.
	SQL transaction
		Related sequence of SQL statements which is processed by UDS/SQL either as a whole or not at all. This method ensures that the database(s) is/are always in a consistent state.
	SSIA
		See Subschema Information Area.
	SSIA-RECORD
		UDS/SQL-internal record type, located in the DBDIR. Records belonging to this type are, for example, the Schema Information Area (SIA) and the Subschema Information Areas (SSIAs).
	SSITAB module
		Module generated by the BCALLSI utility routine; makes available the subschema information required by CALL DML programs.
	SSL
		See Storage Structure Language.
	standard set
		A set other than a dynamic, implicit or SYSTEM set.
	statement code
		Number stored in the first part of the DATABASE-STATUS item. Its function is to indicate which DML statement resulted in an exception condition.
	status code
		Number stored in the second part of the DATABASE-STATUS item. It indicates which exception condition has occurred.
	Storage Structure Language (SSL)
		Formalized language for describing the storage structure.
	string
		A series of consecutive alphanumeric characters.
	subcontrol system
		Component for the independent DBH . Responsible for control functions.
	subschema
		Section of a schema  required for a particular  application ; it can be restructured, within limits, for the intended application; a subschema is defined by means of the  Subschema DDL .
	Subschema DDL
		Formalized language for defining a subschema .
	Subschema Information Area (SSIA)
		The SSIA contains all subschema information required by the DBH  to carry out, on behalf of the user, the  database  accesses permitted within the specified  subschema . The  DBH  loads the SSIA into main memory when it is referenced in a  READY  command.
	subschema module
		Module resulting from subschema  compilation when a  COBOL DML  program is compiled. It must be linked in to the  application program  and includes the  USER WORK AREA  ( UWA ) as well as the  RECORD AREA , which is also part of the  base interface block  ( BIB ). The name of the subschema module is the first 8 bytes of the subschema name.
	subschema record
		Record  defined in the  Subschema DDL .
	SUB-SCHEMA SECTION
		In COBOL programs with DML  statements: section of the DATA DIVISION used for specifying the schema name and the subschema name.
	subtransaction
		In a distributed transaction , all the  processing chains  that address the databases in  one   configuration  form a subtransaction.
	system area
		Realm required only by UDS/SQL. The system areas of a database include: the Database Directory (DBDIR), the Database Compiler Realm (DBCOM), the COBOL Subschema Directory (COSSD)
	system break information
		Indicates whether the database is consistent or inconsistent.
	system buffer pools
		Input/output buffer for database pages (see page). The buffer is part of the common pool (independent DBH) or the DBH work area (linked-in DBH). Its size is determined by the DBH load parameters 2KB-BUFFER-SIZE, 4KB-BUFFER-SIZE or 8KB-BUFFER-SIZE.
	system managed pubset
		A system managed pubset consists of one or more volume sets which, as with an SF pubset, comprise a collection of multiple homogeneous disks; here, too, homogeneity relates to particular physical properties such as disk format and allocation unit.
	SYSTEM record
		See anchor record.
	SYSTEM set
		Set whose owner record type is the symbolic record type SYSTEM.
T
	table, multi-level
		See multi-level table.
	table (SQL)
		A table in the context of SQL corresponds to a UDS/SQL record type.
	table header
		Contains general information on a table or table page: the table type and the level number of the table page, the number of reserved and current entries in this table page, the chaining reference to other table pages on the same level, the pointer to the associated table page on the next higher level, the pointer to the page containing the last table on the main level (for the highest-level table only).
	table page
		Page containing a table or part of a table. If a table which does not extend over several pages or the highest level of a multi-level table is concerned, "table page" only refers to the object involved, not the entire page.
	TANGRAM
		(Task and Group Affinity Management) Subsystem of BS2000 that plans the allocation of processors for task groups which access large quantities of shared data in multi-task applications.
	task attribute TP
		There are 4 task attributes in BS2000: SYS, TP, DIALOG and BATCH. Special runtime parameters that are significant for task scheduling are assigned to each of these task attributes. In contrast to the other task attributes, the TP attribute is characterized by optimized main memory management that is specially tailored to transaction processing requirements.
	task communication
		Communication between the DBH modules . See also  common pool .
	task deadlock
		See deadlock .
	task priority
		In BS2000, it is possible to define a priority for a task. This priority is taken into account when initiating and activating the task. Priorities may be fixed or variable. Variable priorities are adapted dynamically; fixed priorities do not change. Note that UDS/SQL server tasks should be started with a fixed priority in order to ensure consistent performance.
	TCUA
		See Transaction Currency Area.
	time acknowledgment
		Message sent by the UDS-D task  to the remote  application program  to indicate that there is still a  DML  statement being processed.
	transaction (TA)
		Related sequence of DML  statements which is processed by UDS/SQL either as a whole or not at all. This method ensures that the  database(s)  is/are always in a consistent state.  For UDS-D: The total set of  subtransactions  active at a given time.
	transaction, committing a
		Terminating a transaction  with FINISH, i.e. all updates performed within the transaction are committed to the  database .
	transaction, rolling back a
		Terminating a transaction with FINISH WITH CANCEL, i.e. all updates performed on the database within the transaction are rolled back.
	Transaction Currency Area (TCUA)
		Contains currency information.
	transaction identification (TA-ID)
		Assigned by the DBH to identify a particular transaction. Can be requested with the DAL command DISPLAY.
	transfer pool
		UDS-D-specific storage area in which the UDSCT receives the BIBs from remote application programs.
	two-phase commit protocol
		Procedure by which a distributed transaction that has made changes in at least one remote configuration is terminated in such a way as to safeguard inter-configuration consistency or UDS/SQL openUTM-D consistency. The two-phase commit is controlled by the distribution component in the user task if the transaction is distributed via UDS-D. by openUTM-D if the transaction is distributed via openUTM-D or via openUTM-D and UDS-D.
U
	UDSADM
		Module of the independent DBH; executes in the administrator task.
	UDSHASH
		Module generated by the BGSIA utility routine. It contains the names of all the hash routines defined in the Schema DDL.
	UDSNET
		Distribution component in the user task.
	UDSSQL
		Start module of the independent DBH; executes in the master task.
	UDSSUB
		Start module of the independent DBH; executes in the server task.
	UDS-D task UDSCT
		Task started for each configuration by UDS/SQL so that it can participate in distributed processing with UDS-D.
	UDS/SQL / openUTM-D consistency
		A transaction that has updated both openUTM data and UDS/SQL databases is terminated in such a way that the openUTM data and the UDS/SQL databases are either updated together or not at all.
	UDS/SQL pubset declaration
		Declaration in a pubset declaration job variable for restricting the UDS/SQL pubset environment. This reduces or prevents the risk of file names being ambiguous.
	unique throughout the network
		Unique in all the computers that are included in the network.
	user database
		The realms and files of the database required by the user in order to be able to store data in, and to retrieve data from a database are: the Database Directory (DBDIR), the user realms the module library for hash routines (HASHLIB).
	user realm
		A realm defined in the realm entry of the Schema DDL. It contains, among other things, the user records.
	user task
		Execution of an application program or openUTM program, including the parts linked by the system.
	USER-WORK-AREA (UWA)
		Transfer area for communication between the application program and the DBH.
	UTM
		See openUTM.
	UWA
		See USER-WORK-AREA (UWA) .
V
	vector
		Item with repetition factor. The repetition factor must be greater than 1. It specifies how many duplicates of the item are combined in the vector.
	version number, internal
		See internal version number.
W
	warm start
		A warm start is performed by UDS/SQL if an inconsistent database is attached to a session. For UDS/SQL this involves applying all updates of completed transactions to the database which have not yet been applied, rolling back all database transactions that are open, and making the database consistent. The related RLOG file and the DB status file are required for a warm start.