One more question on nav-app

Howdy Y'All (Texan for Hello! ;-)
 
One more question, I am having trouble understanding the app-nav (from the doco).
 
is this a sample to illustrate that I can define page navigation rules among various web clients (struts,jsf,ww)?
 
and, also to illustrate the creation of piece-parts of  a single UI page in different frameworks/tag libs?
 
if none of the above, is there a way in keel to have a shared navigation rules (shared controller) among web-ui-frameworks?
 
I know I need to get into the code examples, but I figured that it's not harm in asking; right ? ;-)
 
Thx