I was searching the web around for relevant information about this, but all I could find are incomplete or outdated information.
So consider this: You have your typical business website, but every link to static page point to just one iFrame. So there is no navigation outside of the main page. As far as I know, it is important to have good URL links with good keywords, but since everything is iFrame, there are no urls, outside of w-ww.something.com (no /our-producs or /about-us etc., just one parent page). So does that affect negatively the page ranking? I believe the iFrame content is not indexed at all, isn't it?