Is there any way to actually turn off expansions?

[xplodr]

I am trying to lock out expansions to make my server vanilla only for now and later I want to be able to unlock kunark, vel, luclin, pop, god etc. over time. Is there an easy way to do this? Someone told me about the world:ExpansionSetting but I don't understand the value. The default is 16383. Does anyone know what that means? Can I change that to a different value to lock out all expansions and then to another for just vanilla and kunark, vanilla kunark and vel, van kun vel and luc, etc.?