16 Citation
Papers using secondary (i.e., from other sources) data, materials, or analysis code must cite those artifacts in the TOP statement. All citations should be to persistent/stable identifiers (DOIs) whenever possible. If creators of data, materials, or code have provided a preferred citation, that source should be cited, along with a way for readers to access the shared material (e.g., on a website or in a repository).
Note, secondary analysis code includes software packages (e.g., R packages), as well as custom analysis code (e.g., code that you, as authors, did not write, but that someone else prepared for a specific use). The majority of papers will have some research software to cite, and it is often overlooked or forgotten. Remember to include version numbers with any software packages. If the amount of information is extensive, a supplementary table can be included with the relevant version and citation information.
You might be tempted to provide citations in other parts of the Method or Results sections (e.g., Analysis Plan for secondary code or Materials for secondary materials), but for completeness, such information should be relocated to the TOP statement. Citations in the TOP statement should be, where possible, to the source of the material, data, software or code, rather than to papers that only describe the material, but do not provide access to it. Such descriptive citations can be included in the main text of the paper, if desired. When data, materials, or code are primary (i.e., created by your author team and published alongside your article), remember to openly license those artifacts and see the Open Data, Open Materials, and Open Code sections for more guidance. When data, materials, or code are secondary, make sure to cite those artifacts as described here, and avoid sharing copies those artifacts in full to avoid issues with copyright (unless they are permissively licensed to allow such sharing).