HP OpenVMS Systems Documentation

HP Pascal for OpenVMS
Language Reference Manual

indexed file organization : A file organization in which each file component must contain a primary key and, optionally, alternate keys. HP Pascal uses the primary key to store components, and uses program-specified keys to build indexes and to retrieve data. See also key.

initial-state specifier: A constant expression, used with the reserved word VALUE, that initializes a variable, a constant, or a data type in the declaration section. See also constant expression.

inspection mode: A file state that indicates when input is being read from a file.

interface module: A module that produces an environment file, that contains data that is not likely to change, and that provides access to more restricted data in an implementation module. See also environment file and implementation module.

internal file: A file temporarily contained in memory that has no name and is not retained after the program finishes execution.

item list : A data structure that contains a sequence of control structures that provide input to a OpenVMS system service and that describes where the service should place its output. An item list can have an arbitrary number of cells and is terminated with a longword of value 0.

key (or, key field) : A value in a component of a file of indexed organization that HP Pascal uses to build indexes into the file. Each key is identified by its location within the component, its length, and its data type. See also alternate key, index, and primary key.

keyed access : Random file access by key value. See also random access.

key of reference : A key used by HP Pascal to determine the index to use when sequentially accessing components of an indexed file. See also key, indexed file organization, and sequential access method.

label: A tag, declared in the LABEL declarations section, that makes an executable statement accessible to a GOTO statement.

language extensions: See HP Pascal extension.

lazy lookahead: See delayed device access.

lexical elements: Characters and identifiers that have meaning to a compiler, such as the legal character set, special symbols, predeclared identifiers, and reserved words.

lock : Action taken by HP Pascal that prevents other programs from accessing a file component while your program reads or writes that same component.

module: A set of instructions that can be compiled, but not executed, by itself. Module blocks contain only a declaration section, which can include an initialization (TO BEGIN DO) and a finalization (TO END DO) section.

module heading: See module.

multidimensional array: An array whose components are also arrays.

name string: A special form of constant expression required by some attributes. The name string is equivalent to a Pascal character-string constant with one exception: name strings cannot use the extended-string syntax. See also attribute and extended-string format.

natural alignment: An attribute of certain data items that refers to the placement of the data, such that the lowest addressed byte has an address that is a multiple of the size of the data in bytes. Natural alignment for a byte is any byte address, natural alignment for a word is any byte address that is a multiple of 2, natural alignment for a longword is any byte address that is a multiple of 4, and so on.

nonpositional syntax: A syntax for passing actual parameters that allows you to specify parameters in any order you want. The syntax requires that you specify the name of the formal parameter, followed by the assignment operator (:=), followed by the actual parameter.

nonstatic type: A type whose objects contain a run-time component; a type is nonstatic if it is a schema type or if its type is derived from a schema type.

optimization: See compiler optimization.

parameter-passing mechanism: The method by which Pascal passes the actual parameter to the formal parameter. HP Pascal passing mechanisms include passing by immediate value, by reference, and by descriptor.

parameter-passing semantics: The characteristics of a parameter expected by a routine declaration, as specified by the formal parameter. HP Pascal parameter-passing semantics include value, variable, routine, and foreign parameters.

passing mechanism: See parameter-passing mechanism.

position independent code: Machine code that operates successfully wherever it is positioned in memory.

positional syntax: A syntax for passing actual parameters that specifies that the parameters in the actual and formal lists must correspond exactly from left to right, item by item, through both lists.

predeclared identifier: A character string that is predeclared by the compiler to have a given meaning but that can be redefined in a program. HP Pascal predeclared identifiers include names of data types, symbolic constants, file variables, procedures, and functions.

primary key : A key value in components of a file of indexed organization that indicates the order in which HP Pascal stores the file components.

procedure: A subprogram that contains one or more statements to be executed once the procedure is called.

program: A set of instructions that can be compiled and executed by itself. Program blocks contain a declaration and an executable section.

program heading: See heading.

property : A characteristic of a program section (PSECT) that determines memory allocation and sharing. The term property is synonymous with the OpenVMS term attribute.

random access : An access method that allows you to access a specified component in a relative or indexed file (and also in sequential files with fixed-length components). The order of access is not dependent on the order in which the components are stored.

record: A group of components, called fields, which can be of various data types.

recursion: The act of a routine directly or indirectly calling itself.

redefinable reserved word: An identifier that HP Pascal reserves for its own use but that you can redefine if you choose. If you redefine these words, the original function of the reserved word becomes unavailable within the block in which you redeclare the word.

relative component number : A cell number in a file of relative organization.

relative file organization : A file organization that consists of a series of component positions, called cells, numbered consecutively from 1 to n. The numbered, fixed-length cells enable HP Pascal to calculate the component's physical position in the file.

reserved word: An identifier that HP Pascal reserves for its use to designate data types, statements, and operators. You cannot redefine these identifiers.

routine: A subprogram; a function or procedure. See also function and procedure.

routine heading: See heading.

run-time expression: An expression that results in a value at the time you run your program. See also constant expression.

schema family: All types that are derived only from discriminating the same schema type, though the actual-discriminant values may vary. See also actual discriminant.

schema type: A user-defined construct that provides a template for a family of distinct data types. By discriminating a schema type, you create a valid data type. See also data type, discriminated schema type, and undiscriminated schema type.

semantics: See parameter-passing semantics.

sequential access method: A component access method in which storage or retrieval begins at a designated position in the file and continues through the file according to the component's position in storage.

sequential file organization: A file organization in which file components are stored one after the other, in the order in which they were written to the file.

set: A collection of data items of the same ordinal type. See also base type.

short circuiting: Compiler evaluation of an expression from left to right that stops as soon as the overall result can be determined. See also expression.

static type: A type whose object can be fully described at compile time, a type that is not derived from a schema type.

static variable allocation: Allocation for a variable that occurs only once and that exists for the duration of the executable image's execution.

stream component format: A component format that is a continuous stream of bytes and that is delimited by a character called a terminator.

subscript: An ordinal index, or subscript, that designates an individual array element's position in the array. See also array.

terminator: A delimiting character for a stream component that HP Pascal also recognizes as a valid part of the component data.

TIE: See Translated Image Environment.

translated code: OpenVMS Alpha code created by the VAX Environment Software Translator to run on OpenVMS Alpha systems. See also Translated Image Environment and VAX Environment Software Translator.

Translated Image Environment: An OpenVMS Alpha systems shareable image that is applied to a translated image at run time. TIE provides an environment similar to OpenVMS VAX for the translated image and processes all interactions with the native OpenVMS Alpha system. TIE is selected with a switch at compile time.

undefined mode: A file state that indicates when the file is in an undefined state of processing.

undiscriminated schema type: A schema type that has not been provided actual discriminants. These types are used as the domain type of a pointer or as a formal parameter.

unextended Pascal standard: The International Standard ISO 7185-1989. See also Extended Pascal standard.

user-action function : A function that you write and provide to HP Pascal to use Record Management Services (RMS) features to open or close a file.

variable-length component format : A component format that specifies that file components have lengths that vary. See also component and component format.

VAX Environment Software Translator (VEST): A software application that analyzes a VAX system binary image and creates a functionally equivalent translated image that runs on OpenVMS Alpha systems.