adding public domain mark as example of open licenses

[philipashlock]

This should be the preferred "open license" as per existing law mentioned in the paragraph on this page

[konklone]

👍

I commented on this over at #5, but I'd like to make the point visible on this thread too - the Public Domain Mark is the appropriate accompanying language for government information, which is already public domain. So this should definitely be on the list.

I would go further, and separate the list of licenses into two lists: one for government-produced information that links to appropriate language indicating that the information is already in the public domain (such as the Public Domain Mark), and one for third-party information or information whose status is ambiguous that lists licenses appropriate for releasing this information (such as the ones currently listed).

As it stands, the licenses currently listed in the master branch (CC0, CC-BY, CC-BY-SA, and the GFDL) all only address information that is currently copyrighted and capable of being licensed - and government produced information doesn't meet this criteria.

[haleyvandyck]

Thanks @philipashlock and @konklone for the great additions here. It is our understanding that the public domain mark actually distinguishes information that is available under world-wide public domain. While we agree with the sprit of finding and adopting a tool to distinguish information with in the public domain, given that in this context we are discussing data in the US public domain specifically we think this might not be the correct tool to add.

Thanks for flagging this though-- we are in the process of developing further clarifications on this point specifically which we will be posting to project open data for additional feedback soon. Thanks!