“The Public Domain Certification should only be used to certify a work that is already in the public domain.”
Which would not apply to any original works or even re-typesets being submitted here, since not every legislative domain permits the relinquishing of copyright. However, CC advocate the use of the “
CC0” licence for those wanting a licence as close to the actual state of the public domain, and which does a similar job to allowing the submitter’s work to be “freely reproduced, distributed, transmitted, used, modified, built upon, or otherwise exploited by anyone for any purpose, commercial or non-commercial, and in any way, including by methods that have not yet been invented or conceived”.
The commercial use bit is one of the stumbling blocks – quite a number of works here represent considerable investment of time, effort and ingenuity on the submitters, and such licences allow anyone else to exploit their work commercially (like it being included in eBay sales). I wasn't aware that editing or composing music was so naturally lucrative in the global economy that would allow editors and composers to cavalierly give their work away for others to make money from!
Regards, Philip