Terrain chunks with less than 20 minutes (1 Minecraft day) of inhabited time will periodically be deleted.
This allows for nice things on a multiplayer server:
- many of the cities in the End will regenerate so elytra are more common
- new structures and biomes in new versions get to appear closer to spawn
- keeps the world size low
Chunks with more than 1 Minecraft day of inhabited time become permanent chunks and never get deleted.
The maps show which are which.
We use mcaselector and a inhabitedTime <= 20 minutes filter to accomplish this.