World Machine Texture Splatmap Question

So, I’ve used a basic coverage node in World Machine (it basically just puts colors on certain areas of the terrain), and applied the colors Red Green and Blue to be the height input for different materials on my landscape respectively. But if there’s only red green and blue channels to be used, does this mean that I can only have 3 textures on my landscape without painting manually?

I suppose you can have four, where the fourth would show through if there’s no red, green, or blue.