Language Reference

How to Use This Book

This document is intended primarily as a reference tool, not as a Fortran or programming tutorial. Programmers using this document should have some knowledge of Fortran concepts and have previous experience in writing Fortran application programs.

• Highlighting Conventions
• How to Read Syntax Diagrams
• Notes on the Examples in This Book
• Related Documentation
• Standards Documents

The document is divided into three main parts:

• Concepts and Elements provides some general background on the items and constructs you can use to write XL Fortran programs.
• Statements and Directives provides an alphabetical reference of all XL Fortran statements. This section also provides reference information on both comment form and noncomment form directives, including the symmetric multiprocessing (SMP) directives.
  • Each statement description includes a brief explanation of purpose, a syntax diagram, a detailed discussion of rules concerning the statement, examples, and references to any related information. This section is particularly useful to programmers who know which statement they need, but want details on syntax or rules.
  • Directive descriptions are organized in a manner similar to the Statements section described above. It is important to gain an understanding of the directives contained in this section before programming using SMP.
• Intrinsic and Library Procedures provides an alphabetical reference to all XL Fortran:
  • Intrinsic procedures
  • Service and utility procedures
  • OpenMP execution environment and lock routines
  • Pthreads library module

Appendix A, Compatibility Across Standards discusses upwards and backwards compatibility across the FORTRAN 77, Fortran 90 and Fortran 95 standards. Appendix B, ASCII and EBCDIC Character Sets displays the ASCII and EBCDIC character sets. The Glossary provides an alphabetical reference to terms commonly used in this document.

See Highlighting Conventions for details on how IBM Extensions and Fortran 95 information are identified in this document.