Well, I assumed that this is about constraints on base class methods, like
here:

  class A {
    public virtual void Foo<T>() where T: ISomething {
    }
  }

  class B : A {
    public override void Foo<T>() {
    }
  }

This code compiles. What I thought the paragraph was about was that when I
decided to add constraints to the overridden method in B as well, that
these constraints couldn't be more restrictive than those on the
overridden method. But when I tried to test this by changing the method
signature of B.Foo to this:

  public override void Foo<T> where T: ISomething, new()

I found that this isn't allowed at all - the compiler just says
"Constraints for override and explicit interface implementation methods
are inherited from the base method so cannot be specified directly." So
now I have to admit I really have no idea from the top of my head what
this paragraph is talking about.

               Oliver Sturm