[Rd] legitimate use of :::

[Trevor Davis]

> This is a good solution. Do I need to specify the original License etc? And
> what about a helper function such as stats:::n.knots? This will not appear
> in the manual of my package. Is it sufficient in this case to document the
> authorship in the source (and perhaps a README as you suggested)?

If the license is the same as your projects you just need the proper
copyright notice.
As Hadley suggests it is a good idea to also document the appropriate authorship
in the Authors field in the DESCRIPTION as well.

If the license is different but permissive than then it typically doesn't need
go into DESCRIPTION or a separate LICENSE file but the permissive
license text does usually need to either go
into inst/COPYRIGHT or at the top of the relevant code file:

  https://www.softwarefreedom.org/resources/2007/gpl-non-gpl-collaboration.html
  https://www.softwarefreedom.org/resources/2012/ManagingCopyrightInformation.html

If the license is more restrictive
you must either convert your project or not use the code at all
although for very small code snippets you might have fair use rights
(at least in the United States).

- Trevor