Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Language Reference Manual

Glossary

This glossary defines terms for all platforms and releases of PL/I. It might contain terms that this manual does not use. If you do not find the terms for which you are looking, see the index in this manual or IBM Dictionary of Computing, SC20-1699.

 

 

A

access
To reference or retrieve data.
action specification
In an ON statement, the ON-unit or the single keyword SYSTEM, either of which specifies the action to be taken whenever the appropriate condition is raised.
activate (a block)
To initiate the execution of a block. A procedure block is activated when it is invoked. A begin-block is activated when it is encountered in the normal flow of control, including a branch. A package cannot be activated.
activate (a preprocessor variable or preprocessor entry point)
To make a macro facility identifier eligible for replacement in subsequent source code. The %ACTIVATE statement activates preprocessor variables or preprocessor entry points.
active
The state of a block after activation and before termination. The state in which a preprocessor variable or preprocessor entry name is said to be when its value can replace the corresponding identifier in source program text. The state in which an event variable is said to be during the time it is associated with an asynchronous operation. The state in which a task variable is said to be when its associated task is attached. The state in which a task is said to be before it has been terminated.
actual origin (AO)
The location of the first item in the array or structure.
additive attribute
A file description attribute for which there are no defaults, and which, if required, must be stated explicitly or implied by another explicitly stated attribute. Contrast with alternative attribute.
adjustable extent
The bound (of an array), the length (of a string), or the size (of an area) that might be different for different generations of the associated variable. Adjustable extents are specified as expressions or asterisks (or by REFER options for based variables), which are evaluated separately for each generation. They cannot be used for static variables.
aggregate
See data aggregate.
aggregate expression
An array, structure, or union expression.
aggregate type
For any item of data, the specification whether it is structure, union, or array.
allocated variable
A variable with which main storage is associated and not freed.
allocation
The reservation of main storage for a variable. A generation of an allocated variable. The association of a PL/I file with a system data set, device, or file.
alignment
The storing of data items in relation to certain machine-dependent boundaries (for example, a fullword or halfword boundary).
alphabetic character
Any of the characters A through Z of the English alphabet and the alphabetic extenders #, $, and @ (which can have a different graphic representation in different countries).
alphameric character
An alphabetic character or a digit.
alternative attribute
A file description attribute that is chosen from a group of attributes. If none is specified, a default is assumed. Contrast with additive attribute.
ambiguous reference
A reference that is not sufficiently qualified to identify one and only one name known at the point of reference.
area
A portion of storage within which based variables can be allocated.
argument
An expression in an argument list as part of an invocation of a subroutine or function.
argument list
A parenthesized list of zero or more arguments, separated by commas, following an entry name constant, an entry name variable, a generic name, or a built-in function name. The list becomes the parameter list of the entry point.
arithmetic comparison
A comparison of numeric values. See also bit comparison, character comparison.
arithmetic constant
A fixed-point constant or a floating-point constant. Although most arithmetic constants can be signed, the sign is not part of the constant.
arithmetic conversion
The transformation of a value from one arithmetic representation to another.
arithmetic data
Data that has the characteristics of base, scale, mode, and precision. Coded arithmetic data and pictured numeric character data are included.
arithmetic operators
Either of the prefix operators + and -, or any of the following infix operators: + - * / **
array
A named, ordered collection of one or more data elements with identical attributes, grouped into one or more dimensions.
array expression
An expression whose evaluation yields an array of values.
array of structures
An ordered collection of identical structures specified by giving the dimension attribute to a structure name.
array variable
A variable that represents an aggregate of data items that must have identical attributes. Contrast with structure variable.
ASCII
American National Standard Code for Information Interchange.
assignment
The process of giving a value to a variable.
asynchronous operation
The overlap of an input/output operation with the execution of statements. The concurrent execution of procedures using multiple flows of control for different tasks.
attachment of a task
The invocation of a procedure and the establishment of a separate flow of control to execute the invoked procedure (and procedures it invokes) asynchronously, with execution of the invoking procedure.
attention
An occurrence, external to a task, that could cause a task to be interrupted.
attribute
A descriptive property associated with a name to describe a characteristic represented. A descriptive property used to describe a characteristic of the result of evaluation of an expression.
automatic storage allocation
The allocation of storage for automatic variables.
automatic variable
A variable whose storage is allocated automatically at the activation of a block and released automatically at the termination of that block.

B

base
The number system in which an arithmetic value is represented.
base element
A member of a structure or a union that is itself not another structure or union.
base item
The automatic, controlled, or static variable or the parameter upon which a defined variable is defined.
based reference
A reference that has the based storage class.
based storage allocation
The allocation of storage for based variables.
based variable
A variable whose storage address is provided by a locator. Multiple generations of the same variable are accessible. It does not identify a fixed location in storage.
begin-block
A collection of statements delimited by BEGIN and END statements, forming a name scope. A begin-block is activated either by the raising of a condition (if the begin-block is the action specification for an ON-unit) or through the normal flow of control, including any branch resulting from a GOTO statement.
binary
A number system whose only numerals are 0 and 1.
binary digit
See bit.
binary fixed-point value
An integer consisting of binary digits and having an optional binary point and optional sign. Contrast with decimal fixed-point value.
binary floating-point value
An approximation of a real number in the form of a significand, which can be considered as a binary fraction, and an exponent, which can be considered as an integer exponent to the base of 2. Contrast with decimal floating-point value.
bit
A 0 or a 1. The smallest amount of space of computer storage.
bit comparison
A left-to-right, bit-by-bit comparison of binary digits. See also arithmetic comparison, character comparison.
bit string constant
A series of binary digits enclosed in and followed immediately by the suffix B. Contrast with character constant. A series of hexadecimal digits enclosed in single quotes and followed by the suffix B4.
bit string
A string composed of zero or more bits.
bit string operators
The logical operators not and exclusive-or (¬), and (&), and or (|).
bit value
A value that represents a bit type.
block
A sequence of statements, processed as a unit, that specifies the scope of names and the allocation of storage for names declared within it. A block can be a package, procedure, or a begin-block.
bounds
The upper and lower limits of an array dimension.
break character
The underscore symbol ( _ ). It can be used to improve the readability of identifiers. For instance, a variable could be called OLD_INVENTORY_TOTAL instead of OLDINVENTORYTOTAL.
built-in function
A predefined function supplied by the language, such as SQRT (square root).
built-in function reference
A built-in function name, which has an optional argument list.
built-in name
The entry name of a built-in subroutine.
built-in subroutine
Subroutine that has an entry name that is defined at compile-time and is invoked by a CALL statement.
buffer
Intermediate storage, used in input/output operations, into which a record is read during input and from which a record is written during output.

C

call
To invoke a subroutine by using the CALL statement or CALL option.
character comparison
A left-to-right, character-by-character comparison according to the collating sequence. See also arithmetic comparison, bit comparison.
character string constant
A sequence of characters enclosed in single quotes; for example, 'Shakespeare''s 'Hamlet:''.
character set
A defined collection of characters. See language character set and data character set. See also ASCII and EBCDIC.
character string picture data
Picture data that has only a character value. This type of picture data must have at least one A or X picture specification character. Contrast with numeric picture data.
closing (of a file)
The dissociation of a file from a data set or device.
coded arithmetic data
Data items that represent numeric values and are characterized by their base (decimal or binary), scale (fixed-point or floating-point), and precision (the number of digits each can have). This data is stored in a form that is acceptable, without conversion, for arithmetic calculations.
combined nesting depth
The deepest level of nesting, determined by counting the levels of PROCEDURE/BEGIN/ON, DO, SELECT, and IF...THEN...ELSE nestings in the program.
comment
A string of zero or more characters used for documentation that are delimited by /* and */.
commercial character

comparison operator
An operator that can be used in an arithmetic, string locator, or logical relation to indicate the comparison to be done between the terms in the relation. The comparison operators are:
compile time
In general, the time during which a source program is translated into an object module. In PL/I, it is the time during which a source program can be altered, if desired, and then translated into an object program.
compiler options
Keywords that are specified to control certain aspects of a compilation, such as: the nature of the object module generated, the types of printed output produced, and so forth.
complex data
Arithmetic data, each item of which consists of a real part and an imaginary part.
composite operator
An operator that consists of more than one special character, such as <=, **, and /*.
compound statement
A statement that contains other statements. In PL/I, IF, ON, OTHERWISE, and WHEN are the only compound statements. See statement body.
concatenation
The operation that joins two strings in the order specified, forming one string whose length is equal to the sum of the lengths of the two original strings. It is specified by the operator ||.
condition
An exceptional situation, either an error (such as an overflow), or an expected situation (such as the end of an input file). When a condition is raised (detected), the action established for it is processed. See also established action and implicit action.
condition name
Name of a PL/I-defined or programmer-defined condition.
condition prefix
A parenthesized list of one or more condition names prefixed to a statement. It specifies whether the named conditions are to be enabled or disabled.
connected aggregate
An array or structure whose elements occupy contiguous storage without any intervening data items. Contrast with nonconnected aggregate.
connected reference
A reference to connected storage. It must be apparent, prior to execution of the program, that the storage is connected.
connected storage
Main storage of an uninterrupted linear sequence of items that can be referred to by a single name.
constant
An arithmetic or string data item that does not have a name and whose value cannot change. An identifier declared with the VALUE attribute. An identifier declared with the FILE or the ENTRY attribute but without the VARIABLE attribute.
constant reference
A value reference which has a constant as its object
contained block, declaration, or source text
All blocks, procedures, statements, declarations, or source text inside a begin, procedure, or a package block. The entire package, procedure, and the BEGIN statement and its corresponding END statements are not contained in the block.
containing block
The package, procedure, or begin-block that contains the declaration, statement, procedure, or other source text in question.
contextual declaration
The appearance of an identifier that has not been explicitly declared in a DECLARE statement, but whose context of use allows the association of specific attributes with the identifier.
control character
A character in a character set whose occurrence in a particular context specifies a control function. One example is the end-of-file (EOF) marker.
control format item
A specification used in edit-directed transmission to specify positioning of a data item within the stream or printed page.
control variable
A variable that is used to control the iterative execution of a DO statement.
controlled parameter
A parameter for which the CONTROLLED attribute is specified in a DECLARE statement. It can be associated only with arguments that have the CONTROLLED attribute.
controlled storage allocation
The allocation of storage for controlled variables.
controlled variable
A variable whose allocation and release are controlled by the ALLOCATE and FREE statements, with access to the current generation only.
control sections
Grouped machine instructions in an object module.
conversion
The transformation of a value from one representation to another to conform to a given set of attributes. For example, converting a character string to an arithmetic value such as FIXED BINARY (15,0).
cross section of an array
The elements represented by the extent of at least one dimension of an array. An asterisk in the place of a subscript in an array reference indicates the entire extent of that dimension.
current generation
The generation of an automatic or controlled variable that is currently available by referring to the name of the variable.

D

data
Representation of information or of value in a form suitable for processing.
data aggregate
A data item that is a collection of other data items.
data attribute
A keyword that specifies the type of data that the data item represents, such as FIXED BINARY.
data-directed transmission
The type of stream-oriented transmission in which data is transmitted. It resembles an assignment statement and is of the form name = constant.
data item
A single named unit of data.
data list
In stream-oriented transmission, a parenthesized list of the data items used in GET and PUT statements. Contrast with format list.
data set
A collection of data external to the program that can be accessed by reference to a single file name. A device that can be referenced.
data specification
The portion of a stream-oriented transmission statement that specifies the mode of transmission (DATA, LIST, or EDIT) and includes the data list(s) and, for edit-directed mode, the format list(s).
data stream
Data being transferred from or to a data set by stream-oriented transmission, as a continuous stream of data elements in character form.
data transmission
The transfer of data from a data set to the program or vice versa.
data type
A set of data attributes.
DBCS
In the character set, each character is represented by two consecutive bytes.
deactivated
The state in which an identifier is said to be when its value cannot replace a preprocessor identifier in source program text. Contrast with active.
debugging
Process of removing bugs from a program.
decimal
The number system whose numerals are 0 through 9.
decimal digit picture character
The picture specification character 9.
decimal fixed-point constant
A constant consisting of one or more decimal digits with an optional decimal point.
decimal fixed-point value
A rational number consisting of a sequence of decimal digits with an assumed position of the decimal point. Contrast with binary fixed-point value.
decimal floating-point constant
A value made up of a significand that consists of a decimal fixed-point constant, and an exponent that consists of the letter E followed by an optionally signed integer constant not exceeding three digits.
decimal floating-point value
An approximation of a real number, in the form of a significand, which can be considered as a decimal fraction, and an exponent, which can be considered as an integer exponent to the base 10. Contrast with binary floating-point value.
decimal picture data
See numeric picture data.
declaration
The establishment of an identifier as a name and the specification of a set of attributes (partial or complete) for it. A source of attributes of a particular name.
default
Describes a value, attribute, or option that is assumed when none has been specified.
defined variable
A variable that is associated with some or all of the storage of the designated base variable.
delimit
To enclose one or more items or statements with preceding and following characters or keywords.
delimiter
All comments and the following characters: percent, parentheses, comma, period, semicolon, colon, assignment symbol, blank, pointer, asterisk, and single quote. They define the limits of identifiers, constants, picture specifications, iSUBs, and keywords.
descriptor
A control block that holds information about a variable, such as area size, array bounds, or string length.
digit
One of the characters 0 through 9.
dimension attribute
An attribute that specifies the number of dimensions of an array and indicates the bounds of each dimension.
disabled
The state of a condition in which no interrupt occurs and no established action will take place.
do-group
A sequence of statements delimited by a DO statement and ended by its corresponding END statement, used for control purposes. Contrast with block.
do-loop
See iterative do-group.
dummy argument
Temporary storage that is created automatically to hold the value of an argument that cannot be passed by reference.
dump
Printout of all or part of the storage used by a program as well as other program information, such as a trace of an error's origin.

E

EBCDIC
(Extended Binary-Coded Decimal Interchange Code). A coded character set consisting of 8-bit coded characters.
edit-directed transmission
The type of stream-oriented transmission in which data appears as a continuous stream of characters and for which a format list is required to specify the editing desired for the associated data list.
element
A single item of data as opposed to a collection of data items such as an array; a scalar item.
element expression
An expression whose evaluation yields an element value.
element variable
A variable that represents an element; a scalar variable.
elementary name
See base element.
enabled
The state of a condition in which the condition can cause an interrupt and then invocation of the appropriate established ON-unit.
end-of-step message
message that follows the listng of the job control statements and job scheduler messages and contains return code indicating success or failure for each step.
entry constant
The label prefix of a PROCEDURE statement (an entry name). The declaration of a name with the ENTRY attribute but without the VARIABLE attribute.
entry data
A data item that represents an entry point to a procedure.
entry expression
An expression whose evaluation yields an entry name.
entry name
An identifier that is explicitly or contextually declared to have the ENTRY attribute (unless the VARIABLE attribute is given) or An identifier that has the value of an entry variable with the ENTRY attribute implied.
entry point
A point in a procedure at which it can be invoked. primary entry point and secondary entry point.
entry reference
An entry constant, an entry variable reference, or a function reference that returns an entry value.
entry variable
A variable to which an entry value can be assigned. It must have both the ENTRY and VARIABLE attributes.
entry value
The entry point represented by an entry constant or variable; the value includes the environment of the activation that is associated with the entry constant.
environment (of an activation)
Information associated with and used in the invoked block regarding data declared in containing blocks.
environment (of a label constant)
Identity of the particular activation of a block to which a reference to a statement-label constant applies. This information is determined at the time a statement-label constant is passed as an argument or is assigned to a statement-label variable, and it is passed or assigned along with the constant.
established action
The action taken when a condition is raised. See also implicit action and ON-statement action.
epilogue
Those processes that occur automatically at the termination of a block or task.
evaluation
The reduction of an expression to a single value, an array of values, or a structured set of values.
event
An activity in a program whose status and completion can be determined from an associated event variable.
event variable
A variable with the EVENT attribute that can be associated with an event. Its value indicates whether the action has been completed and the status of the completion.
explicit declaration
The appearance of an identifier (a name) in a DECLARE statement, as a label prefix, or in a parameter list. Contrast with implicit declaration.
exponent characters
The following picture specification characters:
  1. K and E, which are used in floating-point picture specifications to indicate the beginning of the exponent field.
  2. F, the scaling factor character, specified with an integer constant that indicates the number of decimal positions the decimal point is to be moved from its assumed position to the right (if the constant is positive) or to the left (if the constant is negative).
expression
A notation, within a program, that represents a value, an array of values, or a structured set of values. A constant or a reference appearing alone, or a combination of constants and/or references with operators.
extended alphabet
The uppercase and lowercase alphabetic characters A through Z, $, @ and #, or those specified in the NAMES compiler option.
extent
The range indicated by the bounds of an array dimension, by the length of a string, or by the size of an area. The size of the target area if this area were to be assigned to a target area.
external name
A name (with the EXTERNAL attribute) whose scope is not necessarily confined only to one block and its contained blocks.
external procedure
A procedure that is not contained in any other procedure. A level-2 procedure contained in a package that is also exported.
external symbol
Name that can be referred to in a control section other than the one in which it is defined.
External Symbol Dictionary (ESD)
Table containing all the external symbols that appear in the object module.
extralingual character
Characters (such as $, @, and #) that are not classified as alphanumeric or special. This group includes characters that are determined with the NAMES compiler option.

F

factoring
The application of one or more attributes to a parenthesized list of names in a DECLARE statement, eliminating the repetition of identical attributes for multiple names.
field (in the data stream)
That portion of the data stream whose width, in number of characters, is defined by a single data or spacing format item.
field (of a picture specification)
Any character-string picture specification or that portion (or all) of a numeric character picture specification that describes a fixed-point number.
file
A named representation, within a program, of a data set or data sets. A file is associated with the data set(s) for each opening.
file constant
A name declared with the FILE attribute but not the VARIABLE attribute.
file description attributes
Keywords that describe the individual characteristics of each file constant. See also alternative attribute and additive attribute.
file expression
An expression whose evaluation yields a value of the type file.
file name
A name declared for a file.
file variable
A variable to which file constants can be assigned. It has the attributes FILE and VARIABLE and cannot have any of the file description attributes.
fixed-point constant
See arithmetic constant.
fix-up
A solution, performed by the compiler after detecting an error during compilation, that allows the compiled program to run.
floating-point constant
See arithmetic constant.
flow of control
Sequence of execution.
format
A specification used in edit-directed data transmission to describe the representation of a data item in the stream (data format item) or the specific positioning of a data item within the stream (control format item).
format constant
The label prefix on a FORMAT statement.
format data
A variable with the FORMAT attribute.
format label
The label prefix on a FORMAT statement.
format list
In stream-oriented transmission, a list specifying the format of the data item on the external medium. Contrast with data list.
fully qualified name
A name that includes all the names in the hierarchical sequence above the member to which the name refers, as well as the name of the member itself.
function (procedure)
A procedure that has a RETURNS option in the PROCEDURE statement. A name declared with the RETURNS attribute. It is invoked by the appearance of one of its entry names in a function reference and it returns a scalar value to the point of reference. Contrast with subroutine.
function reference
An entry constant or an entry variable, either of which must represent a function, followed by a possibly empty argument list. Contrast with subroutine call.

G

generation (of a variable)
The allocation of a static variable, a particular allocation of a controlled or automatic variable, or the storage indicated by a particular locator qualification of a based variable or by a defined variable or parameter.
generic descriptor
A descriptor used in a GENERIC attribute.
generic key
A character string that identifies a class of keys. All keys that begin with the string are members of that class. For example, the recorded keys 'ABCD', 'ABCE', and 'ABDF', are all members of the classes identified by the generic keys 'A' and 'AB', and the first two are also members of the class 'ABC'; and the three recorded keys can be considered to be unique members of the classes 'ABCD', 'ABCE', 'ABDF', respectively.
generic name
The name of a family of entry names. A reference to the generic name is replaced by the entry name whose parameter descriptors match the attributes of the arguments in the argument list at the point of invocation.
group
A collection of statements contained within larger program units. A group is either a do-group or a select-group and it can be used wherever a single statement can appear, except as an on-unit.

H

hex
See hexadecimal digit.
hexadecimal
Pertaining to a numbering system with a base of sixteen; valid numbers use the digits 0 through 9 and the characters A through F, where A represents 10 and F represents 15.
hexadecimal digit
One of the digits 0 through 9 and A through F. A through F represent the decimal values 10 through 15, respectively.

I

identifier
A string of characters, not contained in a comment or constant, and preceded and followed by a delimiter. The first character of the identifier must be one of the 26 alphabetic characters and extralingual characters, if any. The other characters, if any, can additionally include extended alphabetic, digit, or the break character.
IEEE
Institute of Electrical and Electronics Engineers.
implicit
The action taken in the absence of an explicit specification.
implicit action
The action taken when an enabled condition is raised and no ON-unit is currently established for the condition. Contrast with ON-statement action.
implicit declaration
A name not explicitly declared in a DECLARE statement or contextually declared.
implicit opening
The opening of a file as the result of an input or output statement other than the OPEN statement.
infix operator
An operator that appears between two operands.
inherited dimensions
For a structure, union, or element, those dimensions that are derived from the containing structures. If the name is an element that is not an array, the dimensions consist entirely of its inherited dimensions. If the name is an element that is an array, its dimensions consist of its inherited dimensions plus its explicitly declared dimensions. A structure with one or more inherited dimensions is called a nonconnected aggregate. Contrast with connected aggregate.
input/output
The transfer of data between auxiliary medium and main storage.
insertion point character
A picture specification character that is, on assignment of the associated data to a character string, inserted in the indicated position. When used in a P-format item for input, the insertion character is used for checking purposes.
integer
An optionally signed sequence of digits or a sequence of bits without a decimal or binary point. An optionally signed whole number, commonly described as FIXED BINARY (p,0) or FIXED DECIMAL (p,0).
integral boundary
A byte multiple address of any 8-bit unit on which data can be aligned. It usually is a halfword, fullword, or doubleword (2-, 4-, or 8-byte multiple respectively) boundary.
interleaved array
An array that refers to nonconnected storage.
interleaved subscripts
Subscripts that exist in levels other than the lowest level of a subscripted qualified reference.
internal block
A block that is contained in another block.
internal name
A name that is known only within the block in which it is declared, and possibly within any contained blocks.
internal procedure
A procedure that is contained in another block. Contrast with external procedure.
interrupt
The redirection of the program's flow of control as the result of raising a condition or attention.
invocation
The activation of a procedure.
invoke
To activate a procedure.
invoked procedure
A procedure that has been activated.
invoking block
A block that activates a procedure.
iteration factor
In an INITIAL attribute specification, an expression that specifies the number of consecutive elements of an array that are to be initialized with the given value. In a format list, an expression that specifies the number of times a given format item or list of format items is to be used in succession.
iterative do-group
A do-group whose DO statement specifies a control variable and/or a WHILE or UNTIL option.

K

key
Data that identifies a record within a direct-access data set. See source key and recorded key.
keyword
An identifier that has a specific meaning in PL/I when used in a defined context.
keyword statement
A simple statement that begins with a keyword, indicating the function of the statement.
known (applied to a name)
Recognized with its declared meaning. A name is known throughout its scope.

L

label
A name prefixed to a statement. A name on a PROCEDURE statement is called an entry constant; a name on a FORMAT statement is called a format constant; a name on other kinds of statements is called a label constant. A data item that has the LABEL attribute.
label constant
A name written as the label prefix of a statement (other than PROCEDURE, ENTRY, FORMAT, or PACKAGE) so that, during execution, program control can be transferred to that statement through a reference to its label prefix.
label data
A label constant or the value of a label variable.
label prefix
A label prefixed to a statement.
label variable
A variable declared with the LABEL attribute. Its value is a label constant in the program.
leading zeroes
Zeros that have no significance in an arithmetic value. All zeros to the left of the first nonzero in a number.
level number
A number that precedes a name in a DECLARE statement and specifies its relative position in the hierarchy of structure names.
level-one variable
A major structure or union name. Any unsubscripted variable not contained within a structure or union.
lexically
Relating to the left-to-right order of units.
library
An MVS partitioned data set or a CMS MACLIB that can be used to store other data sets called members.
list-directed
The type of stream-oriented transmission in which data in the stream appears as constants separated by blanks or commas and for which formatting is provided automatically.
locator
A control block that holds the address of a variable or its descriptor.
locator/descriptor
A locator followed by a descriptor. The locator holds the address of the variable, not the address of the descriptor.
locator qualification
In a reference to a based variable, either a locator variable or function reference connected by an arrow to the left of a based variable to specify the generation of the based variable to which the reference refers. It might be an implicit reference.
locator value
A value that identifies or can be used to identify the storage address.
locator variable
A variable whose value identifies the location in main storage of a variable or a buffer. It has the POINTER or OFFSET attribute.
locked record
A record in an EXCLUSIVE DIRECT UPDATE file that has been made available to one task only and cannot be accessed by other tasks until the task using it relinquishes it.
logical level (of a structure or union member)
The depth indicated by a level number when all level numbers are in direct sequence (when the increment between successive level numbers is one).
logical operators
The bit-string operators not and exclusive-or (¬), and (&), and or (|).
loop
A sequence of instructions that is executed iteratively.
lower bound
The lower limit of an array dimension.

M

main procedure
An external procedure whose PROCEDURE statement has the OPTIONS (MAIN) attribute. This procedure is invoked automatically as the first step in the execution of a program.
major structure
A structure whose name is declared with level number 1.
member
A structure, union, or element name in a structure or union. Data sets in a library.
minor structure
A structure that is contained within another structure or union. The name of a minor structure is declared with a level number greater than one and greater than its parent structure or union.
mode (of arithmetic data)
An attribute of arithmetic data. It is either real or complex.
multiple declaration
Two or more declarations of the same identifier internal to the same block without different qualifications. Two or more external declarations of the same identifier.
multiprocessing
The use of a computing system with two or more processing units to execute two or more programs simultaneously.
multiprogramming
The use of a computing system to execute more than one program concurrently, using a single processing unit.

N

name
Any identifier that the user gives to a variable or to a constant. An identifier appearing in a context where it is not a keyword. Sometimes called a user-defined name.
nesting
The occurrence of:
nonconnected storage
Storage occupied by nonconnected data items. For example, interleaved arrays and structures with inherited dimensions are in nonconnected storage.
null locator value
A special locator value that cannot identify any location in internal storage. It gives a positive indication that a locator variable does not currently identify any generation of data.
null statement
A statement that contains only the semicolon symbol (;). It indicates that no action is to be taken.
null string
A character, graphic, or bit string with a length of zero.
numeric-character data
See decimal picture data.
numeric picture data
Picture data that has an arithmetic value as well as a character value. This type of picture data cannot contain the characters 'A' or 'X.'

O

object
A collection of data referred to by a single name.
offset variable
A locator variable with the OFFSET attribute, whose value identifies a location in storage relative to the beginning of an area.
ON-condition
An occurrence, within a PL/I program, that could cause a program interrupt. It can be the detection of an unexpected error or of an occurrence that is expected, but at an unpredictable time.
ON-statement action
The action explicitly established for a condition that is executed when the condition is raised. When the ON-statement is encountered in the flow of control for the program, it executes, establishing the action for the condition. The action executes when the condition is raised if the ON-unit is still established or a RESIGNAL statement reestablishes it. Contrast with implicit action.
ON-unit
The specified action to be executed when the appropriate condition is raised.
opening (of a file)
The association of a file with a data set.
operand
The value of an identifier, constant, or an expression to which an operator is applied, possibly in conjunction with another operand.
operational expression
An expression that consists of one or more operators.
operator
A symbol specifying an operation to be performed.
option
A specification in a statement that can be used to influence the execution or interpretation of the statement.

P

package constant
The label prefix on a PACKAGE statement.
packed decimal
The internal representation of a fixed-point decimal data item.
padding
One or more characters, graphics, or bits concatenated to the right of a string to extend the string to a required length. One or more bytes or bits inserted in a structure or union so that the following element within the structure or union is aligned on the appropriate integral boundary.
parameter
A name in the parameter list following the PROCEDURE statement, specifying an argument that will be passed when the procedure is invoked.
parameter descriptor
The set of attributes specified for a parameter in an ENTRY attribute specification.
parameter descriptor list
The list of all parameter descriptors in an ENTRY attribute specification.
parameter list
A parenthesized list of one or more parameters, separated by commas and following either the keyword PROCEDURE in a procedure statement or the keyword ENTRY in an ENTRY statement. The list corresponds to a list of arguments passed at invocation.
partially qualified name
A qualified name that is incomplete. It includes one or more, but not all, of the names in the hierarchical sequence above the structure or union member to which the name refers, as well as the name of the member itself.
picture data
Numeric data, character data, or a mix of both types, represented in character form.
picture specification
A data item that is described using the picture characters in a declaration with the PICTURE attribute or in a P-format item.
picture specification character
Any of the characters that can be used in a picture specification.
PL/I character set
A set of characters that has been defined to represent program elements in PL/I.
PL/I prompter
Command processor program for the PLI command that checks the operands and allocates the data sets required by the compiler.
point of invocation
The point in the invoking block at which the reference to the invoked procedure appears.
pointer
A type of variable that identifies a location in storage.
pointer value
A value that identifies the pointer type.
pointer variable
A locator variable with the POINTER attribute that contains a pointer value.
precision
The number of digits or bits contained in a fixed-point data item, or the minimum number of significant digits (excluding the exponent) maintained for a floating-point data item.
prefix
A label or a parenthesized list of one or more condition names included at the beginning of a statement.
prefix operator
An operator that precedes an operand and applies only to that operand. The prefix operators are plus (+), minus (-), and not (¬).
preprocessor
A program that examines the source program before the compilation takes place.
preprocessor statement
A special statement appearing in the source program that specifies the actions to be performed by the preprocessor. It is executed as it is encountered by the preprocessor.
primary entry point
The entry point identified by any of the names in the label list of the PROCEDURE statement.
priority
A value associated with a task, that specifies the precedence of the task relative to other tasks.
problem data
Coded arithmetic, bit, character, graphic, and picture data.
problem-state program
A program that operates in the problem state of the operating system. It does not contain input/output instructions or other privileged instructions.
procedure
A collection of statements, delimited by PROCEDURE and END statements. A procedure is a program or a part of a program, delimits the scope of names, and is activated by a reference to the procedure or one of its entry names. See also external procedure and internal procedure.
procedure reference
An entry constant or variable. It can be followed by an argument list. It can appear in a CALL statement or the CALL option, or as a function reference.
program
A set of one or more external procedures or packages. One of the external procedures must have the OPTIONS(MAIN) specification in its procedure statement.
program control data
Area, locator, label, format, entry, and file data that is used to control the processing of a PL/I program.
prologue
The processes that occur automatically on block activation.
pseudovariable
Any of the built-in function names that can be used to specify a target variable. It is usually on the left-hand side of an assignment statement.

Q

qualified name
A hierarchical sequence of names of structure or union members, connected by periods, used to identify a name within a structure. Any of the names can be subscripted.

R

range (of a default specification)
A set of identifiers and/or parameter descriptors to which the attributes in a DEFAULT statement apply.
record
The logical unit of transmission in a record-oriented input or output operation. A collection of one or more related data items. The items usually have different data attributes and usually are described by a structure or union declaration.
recorded key
A character string identifying a record in a direct-access data set where the character string itself is also recorded as part of the data.
record-oriented data transmission
The transmission of data in the form of separate records. Contrast with stream data transmission.
recursive procedure
A procedure that can be called from within itself or from within another active procedure.
reentrant procedure
A procedure that can be activated by multiple tasks, threads, or processes simultaneously without causing any interference between these tasks, threads, and processes.
REFER expression
The expression preceding the keyword REFER, which is used as the bound, length, or size when the based variable containing a REFER option is allocated, either by an ALLOCATE or LOCATE statement.
REFER object
The variable in a REFER option that holds or will hold the current bound, length, or size for the member. The REFER object must be a member of the same structure or union. It must not be locator-qualified or subscripted, and it must precede the member with the REFER option.
reference
The appearance of a name, except in a context that causes explicit declaration.
relative virtual origin (RVO)
The actual origin of an array minus the virtual origin of an array.
remote format item
The letter R followed by the label (enclosed in parentheses) of a FORMAT statement. The format statement is used by edit-directed data transmission statements to control the format of data being transmitted.
repetition factor
A parenthesized unsigned integer constant that specifies:
  1. The number of times the string constant that follows is to be repeated.
  2. The number of times the picture character that follows is to be repeated.
repetitive specification
An element of a data list that specifies controlled iteration to transmit one or more data items, generally used in conjunction with arrays.
restricted expression
An expression that can be evaluated by the compiler during compilation, resulting in a constant. Operands of such an expression are constants, named constants, and restricted expressions.
returned value
The value returned by a function procedure.
RETURNS descriptor
A descriptor used in a RETURNS attribute, and in the RETURNS option of the PROCEDURE and ENTRY statements.

S

scalar variable
A variable that is not a structure, union, or array.
scale
A system of mathematical notation whose representation of an arithmetic value is either fixed-point or floating-point.
scale factor
A specification of the number of fractional digits in a fixed-point number.
scaling factor
See scale factor.
scope (of a condition prefix)
The portion of a program throughout which a particular condition prefix applies.
scope (of a declaration or name)
The portion of a program throughout which a particular name is known.
secondary entry point
An entry point identified by any of the names in the label list of an entry statement.
select-group
A sequence of statements delimited by SELECT and END statements.
selection clause
A WHEN or OTHERWISE clause of a select-group.
self-defining data
An aggregate that contains data items whose bounds, lengths, and sizes are determined at program execution time and are stored in a member of the aggregate.
separator
See delimiter.
shift
Change of data in storage to the left or to the right of original position.
shift-in
Symbol used to signal the compiler at the end of a double-byte string.
shift-out
Symbol used to signal the compiler at the beginning of a double-byte string.
sign and currency symbol characters
The picture specification characters. S, +, -, and $ (or other national currency symbols enclosed in < and >).
simple parameter
A parameter for which no storage class attribute is specified. It can represent an argument of any storage class, but only the current generation of a controlled argument.
simple statement
A statement other than IF, ON, WHEN, and OTHERWISE.
source
Data item to be converted for problem data.
source key
A key referred to in a record-oriented transmission statement that identifies a particular record within a direct-access data set.
source program
A program that serves as input to the source program processors and the compiler.
source variable
A variable whose value participates in some other operation, but is not modified by the operation. Contrast with target variable.
spill file
Data set named SYSUT1 that is used as a temporary workfile.
standard default
The alternative attribute or option assumed when none has been specified and there is no applicable DEFAULT statement.
standard file
A file assumed by PL/I in the absence of a FILE or STRING option in a GET or PUT statement. SYSIN is the standard input file and SYSPRINT is the standard output file.
standard system action
Action specified by the language to be taken for an enabled condition in the absence of an ON-unit for that condition.
statement
A PL/I statement, composed of keywords, delimiters, identifiers, operators, and constants, and terminated by a semicolon (;). Optionally, it can have a condition prefix list and a list of labels. See also keyword statement, assignment statement, and null statement.
statement body
A statement body can be either a simple or a compound statement.
statement label
See label constant.
static storage allocation
The allocation of storage for static variables.
static variable
A variable that is allocated before execution of the program begins and that remains allocated for the duration of execution.
stream-oriented data transmission
The transmission of data in which the data is treated as though it were a continuous stream of individual data values in character form. Contrast with record-oriented data transmission.
string
A contiguous sequence of characters, graphics, or bits that is treated as a single data item.
string variable
A variable declared with the BIT, CHARACTER, or GRAPHIC attribute, whose values can be either bit, character, or graphic strings.
structure
A collection of data items that need not have identical attributes. Contrast with array.
structure expression
An expression whose evaluation yields a structure set of values.
structure of arrays
A structure that has the dimension attribute.
structure member
See member.
structuring
The hierarchy of a structure, in terms of the number of members, the order in which they appear, their attributes, and their logical level.
subroutine
A procedure that has no RETURNS option in the PROCEDURE statement. Contrast with function.
subroutine call
An entry reference that must represent a subroutine, followed by an optional argument list that appears in a CALL statement. Contrast with function reference.
subscript
An element expression that specifies a position within a dimension of an array. If the subscript is an asterisk, it specifies all of the elements of the dimension.
subscript list
A parenthesized list of one or more subscripts, one for each dimension of the array, which together uniquely identify either a single element or cross section of the array.
subtask
A task that is attached by the given task or any of the tasks in a direct line from the given task to the last attached task.
synchronous
A single flow of control for serial execution of a program.

T

target
Attributes to which a data item (source) is converted.
target reference
A reference that designates a receiving variable (or a portion of a receiving variable).
target variable
A variable to which a value is assigned.
task
The execution of one or more procedures by a single flow of control.
task name
An identifier used to refer to a task variable.
task variable
A variable with the TASK attribute whose value gives the relative priority of a task.
termination (of a block)
Cessation of execution of a block, and the return of control to the activating block by means of a RETURN or END statement, or the transfer of control to the activating block or to some other active block by means of a GO TO statement.
termination (of a task)
Cessation of the flow of control for a task.
truncation
The removal of one or more digits, characters, graphics, or bits from one end of an item of data when a string length or precision of a target variable has been exceeded.
type
The set of data attributes and storage attributes that apply to a generation, a value, or an item of data.

U

undefined
Indicates something that a user must not do. Use of a undefined feature is likely to produce different results on different implementations of a PL/I product. In that case, the application program is in error.
union
A collection of data elements that overlay each other, occupying the same storage. The members can be structures, unions, elementary variables, or arrays. They need not have identical attributes.
union of arrays
A union that has the DIMENSION attribute.
upper bound
The upper limit of an array dimension.

V

value reference
A reference used to obtain the value of an item of data.
variable
A named entity used to refer to data and to which values can be assigned. Its attributes remain constant, but it can refer to different values at different times.
variable reference
A reference that designates all or part of a variable.
virtual origin (VO)
The location where the element of the array whose subscripts are all zero are held. If such an element does not appear in the array, the virtual origin is where it would be held.

Z

zero-suppression characters
The picture specification characters Z and *, which are used to suppress zeros in the corresponding digit positions and replace them with blanks or asterisks respectively.

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