How does a .net 3.5 dll loaded when reference by .net 4 App.

Hi,

    I was trying to understand how .net handles a particular scenario; Created an App in 4.0 .net framework and has a assembly reference to a library created in .net 3.5 framework. How does both the assemblies get loaded and interact. I am assuming that both 3.5 and 4.0 binaries are loaded into separate CLR. Few questions based on this assumption.

1. does both the CLR is loaded in to the app domain separately.

2. if both binaries are loaded into respective CLR how does the inter communication between the class happens, I assume they use LPC/ALPC. what are the policies used on these threads.

3. is it possible that both can run in 4.0 CLR, 3.5 being forced to run in 4.0?

Thanks