What's inside Cardinal Castrillón's briefcase?

Cardinal Castrillón Hoyos met Pope Francis in annouced private audience yesterday, the second such audience granted to him in this pontificate. The first was on May 20, and there have almost certainly been other unannounced informal meetings.

Why is this relevant? Because we know Cardinal Castrillón is the Pope's main contact for all Traditional Catholic matters. And how do we know that?