Word for a relationship specifying that 2 objects don't affect each other (Disjoint?) Thread

I am aiming to create an Enum for a terrain_surface layer. The 3 types of terrain_surface layers I wish to implement are the following:

1. Single - only a single type of terrain_surface is placed on this layer
2. Mixer - when a terrain_surface is placed on this layer, terrain_surfaces that overlap this new terrain_surface have their effectiveness on the terrain reduced. The totality of effectiveness of the set of terrain_surfaces at a particular point on the terrain_layer is 1, eg the effectiveness is a sum of exclusive effectiveness of each terrain_surface.
3. Disjoint - any terrain_surface can be placed on this layer without any implicit constraints/validation on the terrain_surface being placed

How else would you describe a Disjoint relation of this type? This type of relationship between objects is not exclusive to this particular functionality and I am sure I will encounter it again.

Independent.