Region

Regions are features of open spaces, describing whether they are inside or outside of structures. This affects where Monsters may spawn, similar to Areas. The three possible regions are enclosed, exposed, and all.

Enclosed

An enclosed region is mostly or entirely surrounded by foreground blocks, and may have a solid wall of background blocks. Monsters that prefer caves or other shelter spawn here.

Exposed

An exposed region is mostly open to the atmosphere. Monsters that prefer open air to spawn here.

All

The all region covers both of the other two regions. Monsters that don't mind either region spawn here.