Thank you Agustin.
I thought I knew. I appreciate your answer.
Before I study those links, I'd like to know:
1) If that extension ultimately provides us with all the standard navigation, Forward, Backward, to a specific Uri wether it belongs to the same assembly or not, and to a different website...
2) I'm interested in Unity, does the navigation extension with Unity have all the benefits of it's counterpart Mef?
3) Is it the same navigation that allows us to navigate between regions?
Rafael