VAX FORTRAN Language Reference Manual (Ver 5.0)

This document is the VAX FORTRAN Language Reference Manual, dated June 1988, published by Digital Equipment Corporation. It serves as a comprehensive reference detailing the VAX FORTRAN programming language as implemented for VMS systems (Version 5.0 or higher), and supersedes the previous "Programming in VAX FORTRAN" manual.

Intended Audience: The manual is designed for programmers and students who possess a basic understanding of the FORTRAN language.

Content Overview: The manual is structured into ten chapters and four appendices, providing a thorough description of the language:

• Language Fundamentals: Covers the relationship to FORTRAN standards (ANSI FORTRAN-77, ISO 1539-1980 (E)), elements of a source program, character set, general coding rules, and compilation control statements.
• Data Handling: Details data types, data items, and expressions (arithmetic, character, relational, logical), and various assignment statements.
• Program Structure & Control: Describes specification statements for allocating and initializing data and defining symbolic names, along with control statements that govern program flow (e.g., DO loops, IF statements, CALL, RETURN, STOP, PAUSE).
• Subprograms: Explains user-written (statement functions, function subprograms, subroutine subprograms) and VAX FORTRAN-supplied intrinsic functions.
• Input/Output (I/O): Covers I/O statements for data transfer (READ, WRITE, REWRITE, ACCEPT, TYPE, PRINT), I/O formatting rules and descriptors, and auxiliary I/O statements for file management (OPEN, CLOSE, INQUIRE, REWIND, BACKSPACE, ENDFILE, DELETE, UNLOCK).
• Compiler Directives: Introduces directives for parallel processing (CPAR$) and general-purpose functions (CDEC$ IDENT, PSECT, TITLE, SUBTITLE).

Appendices provide supplementary information:

• Additional Language Features (Appendix A): Discusses compatibility features for older FORTRAN programs, such as ENCODE/DECODE, DEFINE FILE, FIND statements, alternative PARAMETER syntax, and the /NOF77 interpretation of EXTERNAL.
• Character Sets (Appendix B): Summarizes FORTRAN, ASCII, and Radix-50 character sets.
• FORTRAN Data Representation (Appendix C): Illustrates how VAX FORTRAN data types are stored in memory.
• Language Summary (Appendix D): Provides a concise summary of expression operators, statements, intrinsic functions, and system subroutines.

New and Expanded Features in Version 5.0:

• Parallel Processing: Introduction of CPARS$ compiler directives for directed decomposition of DO-loops and synchronization of critical regions.
• Enhanced Compiler Control: New CDEC$ general-purpose directives for object module identification, common block attribute modification, and listing headers.
• Improved I/O: Expanded support for descending Indexed Sequential Access Method (ISAM) keys, REWRITE operations for direct access files, and UNLOCK operations for sequential files.
• New Intrinsic Functions: Inclusion of SIZEOF (returns storage bytes) and NWORKERS (returns number of processes executing a routine).