Board Thread:Support Requests - Community Management/@comment-26364189-20151124214635/@comment--20151124221134

Global blocks are the same thing as a local block (cannot edit, comment nor create pages) except it's across the Wikia network. So if you're caught in a global block, that means you may not edit any Wiki until your block expires. Note, that some global blocks last for infinite and you cannot ever edit again under that account name.

Oh an you can tell when someone is globally blocked. It'll say on their profile header "BLOCKED" just like it does locally. When you go to their contributions page it will say "This user is currently blocked across the Wikia network" :)