VAX Pascal Reference Manual (Ver 4.0)

This document, the VAX Pascal Reference Manual (Order Number: AA-L369D-TE, December 1989, Version 4.0), serves as a comprehensive description of the VAX Pascal programming language. It details the language's syntax and semantics, its adherence to various Pascal standards, and its extensions to those standards.

Intended Audience: The manual is designed for experienced applications programmers who already possess a basic understanding of the Pascal language; it is not a tutorial.

Key Contents:

1. Language Fundamentals: Covers lexical elements, Pascal language standards (Unextended and Extended Pascal), and comments.
2. Data Types and Values: Describes ordinal, real, pointer, structured (arrays, records, sets, files), schema, and string types, along with rules for type compatibility.
3. Declaration Sections: Explains the CONST, LABEL, TO BEGIN DO, TO END DO, TYPE, VALUE, and VAR sections for defining constants, labels, user-defined types, and variables.
4. Expressions and Operators: Details how to form expressions using arithmetic, relational, logical, string, and set operators, as well as type conversions and operator precedence.
5. Statements: Explains various executable statements including assignment, CASE, compound, empty, FOR, GOTO, IF, procedure call, REPEAT, WHILE, and WITH statements.
6. Procedures and Functions: Covers routine declarations, calls, and the different types of parameters (value, variable, routine, foreign, schema, conformant) and their passing mechanisms.
7. Program Structure and Scope: Discusses blocks, identifier scope, modules, programs, compilation units, and data sharing (including environment files).
8. Predeclared Routines: Provides an alphabetical reference for numerous built-in functions and procedures for tasks like mathematical computations, character-string manipulation, dynamic allocation, time/date operations, and low-level system interactions.
9. Input and Output Processing: Explains file organizations (sequential, relative, indexed), component formats, access modes, file locking, TEXT files, and a wide array of I/O routines.
10. Attributes: Describes how attributes can be applied to program elements to modify compiler behavior regarding alignment, allocation, error checking, data representation, visibility, and parameter passing.
11. Directives: Outlines compiler directives such as %INCLUDE, %DICTIONARY, %TITLE, and %SUBTITLE.

Appendices provide supplementary information, including the ASCII character set, a language syntax summary, compatibility details between VAX Pascal versions, a summary of VAX Pascal extensions, implementation-defined features, and error detection information.

New and Changed Features in Version 4.0 (since Version 3.5) highlighted in this manual include:

• Schema Types: User-defined templates for families of distinct data types.
• Structured Constructors & Access to Structured Function-Return Values: Enhanced capabilities for specifying structured type values and directly indexing/selecting fields from function results.
• New Logical Operators: AND_THEN and OR_ELSE for controlled evaluation order and short-circuiting.
• Standard Date/Time Routines: DATE, TIME, and GETTIMESTAMP.
• Enhanced String Comparison Functions: EQ, GE, GT, LE, LT, NE for comparisons without blank padding.
• FOR-IN Statement: For iterating through set elements.
• Extended-Digit Integer Notation: For specifying integer constants with various bases.
• VAX Internal Register Manipulation: MFPR and MTPR routines.
• Module Initialization/Finalization: TO BEGIN DO and TO END DO sections.
• STRING Predefined Schema: For variable-length character strings.
• WITH Statement Enhancement: Extended scope for schema discriminants and record fields.
• New Compiler Qualifiers and CHECK Attribute: /DESIGN, /STANDARD (with EXTENDED option), /NOOPTIMIZE qualifiers, and CHECK attribute for run-time validation.

The manual also notes that much of the system-specific and tutorial information has been relocated to the VAX Pascal Reference Supplement for VMS Systems and the VAX Pascal User Manual.