ISO/IEC JTC 1/SC 22/WG 5 - Fortran

1. This document specifies the form and establishes the interpretation of programs expressed in the base Fortran language. The purpose of this document is to promote portability, reliability, maintainability, and efficient execution of Fortran programs for use on a variety of computing systems. 2. This document specifies — the forms that a program written in the Fortran language can take, — the rules for interpreting the meaning of a program and its data, — the form of the input data to be processed by such a program, and — the form of the output data resulting from the use of such a program. 3. Except where stated otherwise, requirements and prohibitions specified by this document apply to programs rather than processors. 4. This document does not specify — the mechanism by which programs are transformed for use on computing systems, — the operations required for setup and control of the use of programs on computing systems, — the method of transcription of programs or their input or output data to or from a storage medium, — the program and processor behavior when this document fails to establish an interpretation except for the processor detection and reporting requirements in items (2) to (10) of 4.2, — the maximum number of images, or the size or complexity of a program and its data that will exceed the capacity of any particular computing system or the capability of a particular processor, — the mechanism for determining the number of images of a program, — the physical properties of an image or the relationship between images and the computational elements of a computing system, — the physical properties of the representation of quantities and the method of rounding, approximating, or computing numeric values on a particular processor, except by reference to ISO/IEC/IEEE 60559:2011 under conditions specified in Clause 17, — the physical properties of input/output records, files, and units, or — the physical properties and implementation of storage.

This part of ISO/IEC 1539 defines facilities in Fortran for the manipulation of character strings of dynamically variable length. This part of ISO/IEC 1539 provides an auxiliary standard for the version of the Fortran language specified by ISO/IEC 1539-1: 1997 and informally known as Fortran 95. A program that conforms with 1539-2: 1994 also conforms with this standard. This part of ISO/IEC 1539 is an auxiliary standard to that defining Fortran 95 in that it defines additional facilities to those defined intrinsically in the primary language standard. A processor conforming to the Fortran 95 standard is not required also to conform to this part of ISO/IEC 1539. However, conformance to this part of ISO/IEC 1539 assumes conformance to the primary Fortran 95 standard. This part of ISO/IEC 1539 prescribes the name of a Fortran module, the name of a derived data type to be used to represent varying-length strings, the interfaces for the procedures and operators to be provided to manipulate objects of this type, and the semantics that are required for each of the entities made accessible by this module. This part of ISO/IEC 1539 does not prescribe the details of any implementation. Neither the method used to represent the data entities of the defined type nor the algorithms used to implement the procedures or operators whose interfaces are defined by this part of ISO/IEC 1539 are prescribed. A conformant implementation may use any representation and any algorithms, subject only to the requirement that the publicly accessible names and interfaces conform to this part of ISO/IEC 1539, and that the semantics are as required by this part of ISO/IEC 1539 and those of ISO/IEC 1539-1 : 1997. It should be noted that a processor is not required to implement this part of ISO/IEC 1539 in order to be a standard conforming Fortran processor, but if a processor implements facilities for manipulating varying length character strings, it is recommended that this be done in a manner that is conformant with this part of ISO/IEC 1539. A processor conforming to this part of ISO/IEC 1539 may extend the facilities provided for the manipulation of varying length character strings as long as such extensions do not conflict with this part of ISO/IEC 1539 or with ISO/IEC 1539-1 : 1997. A module, written in standard conforming Fortran, is referenced in Annex A. This module illustrates one way in which the facilities described in this part of ISO/IEC 1539 could be provided. This module is both conformant with the requirements of this part of ISO/IEC 1539 and, because it is written in standard conforming Fortran, it provides a portable implementation of the required facilities. This module is referenced for information only and is not intended to constrain implementations in any way. This module is a demonstration that at least one implementation, in standard conforming and hence portable Fortran, is possible. It should be noted that this part of ISO/IEC 1539 defines facilities for dynamically varying length strings of characters of default kind only. Throughout this part of ISO/IEC 1539 all references to intrinsic type CHARACTER should be read as meaning characters of default kind. Similar facilities could be defined for non-default kind characters by a separate, if similar, module for each such character kind. This part of ISO/IEC 1539 has been designed, as far as is reasonable, to provide for varying length character strings the facilities that are available for intrinsic fixed length character strings. All the intrinsic operations and functions that apply to fixed length character strings have extended meanings defined by this part of ISO/IEC 1539 for varying length character strings. Also a small number of additional facilities are defined that are appropriate because of the essential differences between the intrinsic type and the varying length derived data type.

ISO/IEC TS 18508:2015 specifies the form and establishes the interpretation of facilities that extend the For-tran language defined by ISO/IEC 1539-1:2010, ISO/IEC 1539-1:2010/Cor 1:2012, and ISO/IEC 1539-1:2010/Cor 2:2013. The purpose of this Technical Specification is to promote portability, reliability, maintainability, and ef-ficient execution of parallel programs written in Fortran, for use on a variety of computing systems. ISO/IEC TS 18508:2015 does not specify formal data consistency model. Developing the formal data consist-ency model is left until the integration of these facilities into ISO/IEC 1539-1.

ISO/IEC TS 29113:2012 specifies the form and establishes the interpretation of facilities that extend the Fortran language defined by ISO/IEC 15391:2010. The purpose of ISO/IEC TS 29113:2012 is to promote portability, reliability, maintainability and efficient execution of programs containing parts written in Fortran and parts written in C, for use on a variety of computing systems.

ISO/IEC 1539-1:2010 specifies the form and establishes the interpretation of programs expressed in the base Fortran language. Its purpose is to promote portability, reliability, maintainability, and efficient execution of Fortran programs for use on a variety of computing systems. ISO/IEC 1539-1:2010 specifies the forms that a program written in the Fortran language may take, the rules for interpreting the meaning of a program and its data, the form of the input data to be processed by such a program, and the form of the output data resulting from the use of such a program. Except where stated otherwise, requirements and prohibitions specified by ISO/IEC 1539-1:2010 apply to programs rather than processors.

ISO/IEC TR 19767:2004 specifies an extension to the module facilities and the syntax of definition of procedures in the programming language Fortran. The Fortran language is specified by ISO/IEC 1539-1:2004. The extension allows program authors to develop the implementation details of concepts in new program units, called "submodules," that cannot be accessed directly by use association, and to define the interface and implementation of procedures separately. The module facility and the syntax of definition of procedures in ISO/IEC 1539-1:2004 are changed by this Technical Report in such a way as to be upwardly compatible with ISO/IEC 1539-1:2004.

ISO/IEC 1539-1:2004 specifies the form and establishes the interpretation of programs expressed in the base Fortran language. Its purpose is to promote portability, reliability, maintainability and efficient execution of Fortran programs for use on a variety of computing systems.