ISO/IEC 1539的这一部分定义了Fortran中用于处理动态可变长度字符串的设施。ISO/IEC 1539的这一部分为ISO/IEC 1539-1:1997规定的Fortran语言版本提供了一个辅助标准，非正式名称为Fortran 95。 符合1539-2:1994的程序也符合本标准。 ISO/IEC 1539的这一部分是Fortran 95定义的辅助标准，因为它定义了基本语言标准中固有定义的附加设施。符合Fortran 95标准的处理器也不需要符合ISO/IEC 1539的本部分。然而，符合ISO/IEC 1539本部分的前提是符合主要Fortran 95标准。 ISO/IEC 1539的这一部分规定了Fortran模块的名称，即用于表示不同数据类型的派生数据类型的名称- 长度字符串、用于操作此类对象的过程和运算符的接口，以及该模块可访问的每个实体所需的语义。 ISO/IEC 1539的本部分未规定任何实施的细节。未规定用于表示定义类型的数据实体的方法，也未规定用于实现ISO/IEC 1539本部分定义的接口的程序或运算符的算法。一致性实现可以使用任何表示和任何算法，但前提是公开访问的名称和接口符合ISO/IEC 1539本部分的要求，并且语义符合ISO/IEC 1539本部分和ISO/IEC 1539-1:1997的要求。 需要注意的是，为了成为符合标准的Fortran处理器，处理器不需要实现ISO/IEC 1539的这一部分，但如果处理器实现了处理变长字符串的功能，建议以符合ISO/IEC 1539这一部分的方式来实现。 符合ISO/IEC 1539本部分要求的处理器可以扩展为处理变长字符串而提供的设施，只要这些扩展不与ISO/IEC 1539本部分或ISO/IEC 1539-1:1997相冲突。 附录A中引用了用符合标准的Fortran编写的模块。该模块说明了提供ISO/IEC 1539本部分所述设施的一种方式。该模块既符合ISO/IEC 1539本部分的要求，又因为它是用符合标准的Fortran编写的，所以它提供了所需设施的便携式实现。本模块仅供参考，无意以任何方式限制实施。本模块演示了至少一种符合标准的可移植Fortran实现。 应该注意的是，ISO/IEC 1539的这一部分定义了仅用于动态改变默认类型字符长度字符串的设施。 在ISO/IEC 1539的这一部分中，所有对固有类型字符的引用都应理解为默认类型的含义字符。对于非默认种类的字符，可以通过一个单独的模块（如果类似的话）为每种此类字符定义类似的功能。 ISO/IEC 1539的这一部分设计得尽可能合理，以便为变长字符串提供适用于固有固定长度字符串的设施。适用于固定长度字符串的所有内在操作和函数都具有ISO/IEC 1539本部分为可变长度字符串定义的扩展含义。此外，由于固有类型和可变长度派生数据类型之间的本质差异，还定义了少量适当的附加设施。

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.