I want to have wasteland spread limited to the biome in overworld.

However, in other myst ages, it would be local, or world-wide, depending on the age (perhaps a symbol in myst to control that?)

Equally, consider what happens if someone gets a wastelands block -- I'm assuming that endermen can pick them up, and silk touch can recover them. What happens if they are planted down in, say, Twilight Forest, or some other dimension?

I'd like to say that some dimensions, such as 1 (Overworld), 7 (TF), or some of the myst ages (symbol controlled, or perhaps an instability issue) can not have it spread far, but others (such as myst worlds with the right symbol, or the right amount of decay) will have it all over.

That is my understanding. A lot will depend on the depth of the Mystcraft API, which I have not reviewed...but XCompWiz is generally agreeable to such features if they do not currently exist.

So...essentially a compatibility setting for Mystcraft, which allows the "age instability" handler to override config settings for cracked sand in specific ages, utilizing the "universal spread" behaviour as a penalty setting?

Or, to be more in line with what we've discussed elsewhere, CS would normally use its default properties, adjusted by configuration, but Mystcraft could employ its "classic" behaviour (the way CS spreads when not limited by biome now) as an instability effect.

Is that right?

EDIT: Missed a point: Consider that "Block" is just one age, that happens to be the age/world that we are on. It just happens to be one that a traveler from D'nI came to, and left some information behind that has been passed on. It just happens to be where the star fissure drops you (just like in canon it goes to earth). It just happens to have a giant underground cave system (Nether) (just like in canon D'nI was a cave system under earth, that was destroyed ...)

... and NOW I find an "edit" button on these things. Who ever decided that hiding user actions/interface buttons was a good thing?

Alright, I think I know exactly what I want now.

By default, Cracked sand can only spread inside a wastelands biome. They won't appear in special worlds (Twilight forest, etc), they can be prevented (or not) on the Overworld.

But a special myst symbol can permit cracked sand to spread over the entire world; as such, it would only be found in Myst ages.

Consider a multiplayer server with PVP or factions. Since Cracked Sand is as easy to pick up as sandstone (not like grass or Mycelium), simply placing one block on the ground outside of enemy territory overnight can really mess up a group's landscape.

This will be part of #50.