On Thu, Oct 1, 2015 at 12:22 PM, Federico Leva (Nemo) <nemowiki@gmail.com> wrote:
The main issue with this effort, on Wikimedia and elsewhere, will be that there is no guarantee we have any metadata about file attribution and copyright status. See also https://meta.wikimedia.org/wiki/File_metadata_cleanup_drive

As that page shows, we have machine-readable metadata for the license at least for 99% of Commons files and 99% of all files. The number probably gets much higher when weighted by number of views. I would certainly not consider missing metadata in 1% of our files the main issue.