What makes code open

Central to Open Code is that the source code is openly accessible and published under an Open Source licence that allows others to use, modify and redistribute it. On platforms such as GitHub, GitLab and Zenodo, the licence is part of the metadata. It can also be stored in a file such as LICENSE.txt in the root directory of the code, or in a README file.

The programming language and software used should also be open so that others can reuse the code. This is the case with R, for example: the language itself is free and Open Source, including all its program libraries and the compiler. Stata and Excel, by contrast, are commercial and use proprietary file formats, which limits reusability.

What FAIR adds

The FAIR Principles for Research Software (FAIR4RS) apply the FAIR data principles to code. Open Code already meets many of them: an open licence is also a clear licence in the FAIR sense, and a public repository makes code accessible. However, FAIR goes further:

• Findable: The code has a persistent identifier such as a DOI and searchable metadata. A GitHub link alone is not enough.
• Accessible: The metadata remain available even if the code itself is no longer available.
• Interoperable: The code exchanges data using common standards and formats.
• Reusable: The code has understandable documentation and traceable information on authors, versions and dependencies.

Open versus FAIR

Conversely, FAIR does not require openness. “Accessible” means accessible under clearly defined conditions, for example only after logging in. FAIR requires a clear licence, but not necessarily an open one. Open describes whether you may use the code; FAIR describes whether you can use it meaningfully.

As with research data, the goal is therefore both: as open as possible and FAIR. Only then do data and code make research reproducible. You can find out how to achieve this in the Creating section.