http://u.qdnx.org/file/erkan-20150208T095733-8g3qjvz.html
@windigo also I think in #legal terms there's a problem now :-( this table (1) says: BY-NC-SA can only be adapted again as BY-NC-SA. Thus, you would actually have to ask all your users on that instance to agree to this licence change for those old posts. I changed my #CC licence in the wiki (2) also once, and have thus separated it by time. (1) https://wiki.creativecommons.org/Frequently_Asked_Questions#If_I_use_a_Creative_Commons-licensed_work_to_create_a_new_work_.28ie_a_derivative_work_or_adaptation.29.2C_which_Creative_Commons_license_can_I_use_for_my_new_work.3F (2) http://skilledtests.com/wiki/Copyright