How will the CivEditor work?

[Doze]

I am just wondering if the Editor will allow you to add a new civ to the list or if you can only edit the ones that are already made?

Example:
If I wanna make the Vikings will I just add it to the list or will my civ replace a civ on the list? This would be bad

 

[Black Fluffy Lion]

I think you can make new civs and change stuff about already existing civs.