Licence for datasets in a R-package

  Dear List,

    I am building a R package which collects ecological data about plant
species from both remote (web) databases and locally stored rda files
(datasets): these "local rda files" are derived from publicly available
databases for which no "official" licenses are provided; I was told by the
creators of these databases that users can use such data provided that the
correct bibliographic reference is always used (the package is already
reminding the users about the correct citation(s) to use). I thought a
CC-by licence would suit this need, thus I am posting here to ask if:

      1) It is possible to distribute these datasets as rda files within my
package (which will be released as GPL=>2, thus two different licences will
be needed for the package)
      2) If a CC-by licence for these datasets could be included in the
DESCRIPTION file, using something like "License: CC-by datasets.rda" for
each rda file (this is based on this stackoverflow thread
<http://stackoverflow.com/a/4317300>, but CC-by is not among the LICENSES
cited in http://www.r-project.org/Licenses/): I've already tried to do
this, but, as a consequence, the "R check" raises a warning.

    I am aware that this is more a licensing issue then a programming
problem, but I went through the R FAQ, "Writing R Extensions" and R-devel
but was not able to sort this problem out (so, please ignore this post if
you find it OT).
    I hope the question is not too messy (this is my first time on R-devel).
    Many thanks for any help you may provide,

If you are not distributing the package to anyone else, you can ignore the
warning about the bad license field.

If you plan to distribute it on a public repository, you should ask the
policies of the repository to find out what to do about this. CRAN policies
are listed at http://cran.r-project.org/web/packages/policies.html.  There's
a link from there to the list of acceptable licenses, and it includes some
CC licenses.

If some parts of the package are licensed one way and others are licensed in
another way, you'll probably need a COPYRIGHTS file to describe it.

Other repositories (e.g. Bioconductor, Github) presumably have their own
policies on this, but I don't know where to find those.

In practice, CRAN maintainers do not allow multiple licenses for parts
of the same package. At least they did not for my package a couple of
months ago.

On Mon, Jul 21, 2014 at 12:54 PM, G?bor Cs?rdi <csardi.gabor at gmail.com> wrote:

In practice, CRAN maintainers do not allow multiple licenses for parts
of the same package. At least they did not for my package a couple of
months ago.

If that is the case then you could put your data files in a separate
package from the code with one depending on the other.

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