Factorio Prototype DocsVersion 1.1.107

A string specifying a collision mask layer.

In addition to the listed layers, there is "layer-13" through "layer-55". These layers are currently unused by the game but may change. If a mod is going to use one of the unused layers it's recommended to use the collision_mask_util.get_first_unused_layer() method from the vanilla library. When not using the library, mods should start at the higher layers because the base game will take from the lower ones.