Hans Küng and Infallibility

Apparently, Hans Küng is beseeching Pope Francis to speak out and clarify Papal Infallibility.  That's an issue that Küng has challenged for quite some time.  I've found in my ten years of being Catholic, that Papal Infallibility is one of those things everyone must agree on, but nobody seems to know how. 

It's worth noting that, from the POV of some Orthodox Christians I've gotten to know, this is a major - and I mean major - sticking point with the non-Roman churches.  If hopes for eventual reconciliation on a full communal level, that is going to have to be dealt with, one way or another.  Anyway, and interesting story.