More detail about "Generate stubs for internal methods"?

I would like to have more details about the “Generate stubs for internal methods”, in .NET Micro Framework option pane of my project.

What does it do?
Why use it?

This is only needed for developers making their own devices. You will probably never need to use it.

From what i understand it is the hard way to do RLP. It creates stubs that you can use to add native, ie C++, code to a library. But you then need to use the porting kit to compile the lib…