Licensing of data supplements to journal articles

Question

I create networks by integrating many databases. Several of the source datasets for my current project are from publication supplements. The publications range from open source to subscription with journal specific licensing. 

Does the license of an article apply to its data supplements? Is data supplement licensing journal specific?

If an article's license applies to supplements and copyright was transferred to the journal, is distribution or reuse of the data supplement solely up to the journal? Do data consumers, such as myself, require the journal's permission rather than the authors' permission for reuse?

Answer 1

If the data was distributed together with the article, I would assume that the license for the article covers the supplement(s) as well – unless a specific license is specified for the supplement(s).

Complicating matters further, Creative Commons licenses earlier than version 4 possibly did not apply well to datasets, at least in certain jurisdictions. However, I am not a lawyer; far from it.