Use for full authors who have made substantial contributions to the package and should show up in the package citation.
Use for package maintainers that collected code (potentially in other languages) but did not make further substantial contributions to the package.
Use for authors who have been contracted to write (parts of) the package and hence do not own intellectual property.
Use for authors who have made smaller contributions (such as code patches etc.) but should not show up in the package citation.
Use for all copyright holders.
Use for the package maintainer.
Use for persons who contributed data sets for the package.
Use for persons or organizations that furnished financial support for the development of the package
Use for persons or organizations responsible for reviewing (parts of) the package.
If the package is part of a thesis, use for the thesis advisor.
If the R code is merely a translation from another language (typically S), use for the translator to R.