Editing Fortran (section)

====Conditional compilation and varying length strings====
In addition to the mandatory "Base language" (defined in ISO/IEC 1539-1 : 1997), the Fortran 95 language also included two optional modules:
* Varying length character strings (ISO/IEC 1539-2 : 2000)
* Conditional compilation (ISO/IEC 1539-3 : 1998)
which, together, compose the multi-part International Standard (ISO/IEC 1539).

According to the standards developers, "the optional parts describe self-contained features which have been requested by a substantial body of users and/or implementors, but which are not deemed to be of sufficient generality for them to be required in all standard-conforming Fortran compilers." Nevertheless, if a standard-conforming Fortran does provide such options, then they "must be provided in accordance with the description of those facilities in the appropriate Part of the Standard".