Landscape Material: What is Blend Modulation?

Hi Epic Games and Staff,

i have a little question about your LandscapeMountains Project.

I have found analysed a lot for understanding, but there is a little piece that i do not understand.

What is Blend Modulation? I know it is a generated Alpha Map from the Texture, but i do not know the usage.

I also saw that it is not used in the project, but it is there.

Here is a picture of the function:

Thanks in advance.

Sincerely yours

Blend modulation commonly refers to refining transition from texture to another by using a mask.