A language standard specifies the form and establishes the interpretation of programs expressed in the language. Its primary purpose is to promote, among vendors and users, portability of programs across a variety of systems.
The vendor-user community has adopted four major Fortran language standards. ANSI (American National Standards Institute) and ISO (International Standards Organization) are the primary organizations that develop and publish the standards.
The major Fortran language standards are:
American National Standard Programming Language FORTRAN, ANSI X3.9-1966. This was the first attempt to standardize the languages called FORTRAN by many vendors.
American National Standard Programming Language FORTRAN, ANSI X3.9-1978. This standard added new features based on vendor extensions to FORTRAN IV and addressed problems associated with large-scale projects, such as improved control structures.
American National Standard Programming Language Fortran, ANSI X3.198-1992 and International Standards Organization, ISO/IEC 1539: 1991, Information technology -- Programming languages -- Fortran. This standard emphasizes modernization of the language by introducing new developments. For information about differences between Fortran 90 and FORTRAN 77, see Features of Fortran 90 or the printed Compaq Fortran Language Reference Manual.
American National Standard Programming Language Fortran and International Standards Organization, ISO/IEC 1539-1: 1997(E), Information technology -- Programming languages -- Fortran. This recent standard introduces certain language elements and corrections into Fortran 90. Fortran 95 includes Fortran 90 and most features of FORTRAN 77. For information about differences between Fortran 95 and Fortran 90, see Features of Fortran 95 or the printed Compaq Fortran Language Reference Manual.
Although a language standard seeks to define the form and the interpretation uniquely, a standard might not cover all areas of interpretation. It might also include some ambiguities. You need to carefully craft your program in these cases so that you get the answers that you want when producing a portable program.
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