So you can have separate settings if a material is in Cycles or Eevee...

If you want stuff to work in both Eevee and Cycles - most of the time it's not a problem, but occasionally you want a different version of a material for one of the render-engines - normally glass. This node would allow you to set a up a material that acts differently depending on what render engine you're in. This would allow for that - and allow you to set up materials that work differently for different render layers, etc.

Is Cycles Is in Scene: "____________" Is in Collection: "_____________" Is in Renderlayer "_____________"