I created a new creative world in my server and would like to make it superflat. Is that possible? If so, how? Thanks!

~Ala

You can't make existing worlds superflat because that would only affect newly generated chunks, the existing chunks wouldn't change and you would get ugly borders. Instead, you have to set the world type when you create the world, take a look at the help for /mv create to see how to do this.