internal, sealed, extern?

what are these in vb.net? I'm just converting a c# code and I want to know what are the equivalent keywords for this in vb.net

Sealed = NotInheritable
Internal = Friend

I dont know if there is an equivalent for extern.

tnx :) what does extern mean in c# anyways

It tells the compiler to look for a function in an external file.

if I not mistaken extern means "Shared" in VB.net

tnx :)
I wish they would have picked one name for all these