[Pyro7480]

How do you know when the Pope is teaching "authoritatively" and when he is not?

It is a matter of formulation. For example, the declaration during Pope John Paul II's papacy that stated that men can only become priests made it clear that this teaching was infallible. Other examples of the Pope using this authority was the declaration of Mary's Immaculate Conception in 1854, and the declaration of Mary's Assumption, body and soul, into heaven during Pope Pius XII's papacy.

[ksen]

Thanks for the info Pyro7480!

Is there a list somewhere of the actual documents that are authoritative? (And please don't say "Catechism" ;^) )

[Salvation]

Correct.