# Is there a "standard" file suffix for modern Fortran code?

**URL:** <https://fortran-lang.discourse.group/t/is-there-a-standard-file-suffix-for-modern-fortran-code/3550>\
**Category:** Uncategorized\
**Created:** [May 25, 2022, 10:56am UTC](https://fortran-lang.discourse.group/t/is-there-a-standard-file-suffix-for-modern-fortran-code/3550 "2022-05-25T10:56:41Z")\
**Posts on this page:** 1\
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**Author:** ![Beliavsky](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@Beliavsky](https://fortran-lang.discourse.group/u/Beliavsky)\
**Post date:** [May 25, 2022, 11:33am UTC](https://fortran-lang.discourse.group/t/is-there-a-standard-file-suffix-for-modern-fortran-code/3550/2 "2022-05-25T11:33:33Z")

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The Fortran 90 standard introduced free source form, and all compilers assume that .f90 code is free source form, so use the .f90 suffix. Your own post explains why .f03 etc. is inadvisable. When I see a new Fortran project on GitHub that uses .f95 .f03 etc. I raise an issue with the form letter below. In most cases that authors have switched to .f90.

> Please consider changing the source file suffixes from .f95 to .f90.  
> The .f90 suffix means that the source code is free format, not that  
> the code conforms to the Fortran 90 standard. Code that uses the .f90  
> suffix can use features from any Fortran standard. All Fortran  
> compilers recognize .f90 as a suffix indicating free source form, but  
> some may not recognize a suffix such as .f95, .f03, .f08, or .f18.  
> Some users may have build tools that do not recognize suffixes other  
> than .f90. Most Fortran source code on GitHub that uses features from  
> a standard more recent than Fortran 90 still uses the .f90 suffix.

I think @certik has said that he would like to reclaim .f for free source form. Currently you need a compiler option to do this.

I have tweeted that

> Since Fortran source files usually have the .f90 or .f suffix, you can Google, for example, “finite element” filetype:f90 and “finite element” filetype:f to find finite element codes.

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