I was under the assumption that the Magisterium is the "teaching authority" of the Church. All those things contained in Scripture and tradition are the sacred Deposit of Faith - in which the Magisterium has divine authority to teach, guard, and defend.
As far as I know, the Popes don't refer to any "levels" of authority "within" the Magisterium (per Pax's sources).
This is the way I understand it:
The Magisterium is AUTHENTIC and it is UNIVERSAL
The Magisterium can be utilized in an EXTRAORDINARY manner or in an ORDINARY manner
The Magisterium is infallible and unable to be mistaken
That's all there is to it...per the Popes.
I can't really tell if we're in agreement or not...
I think we are mostly, perhaps fully in agreement. Dissect this please.....
I was trying to think of examples, and the best example I can think of is simply to take V1, which was headed by Pope Pius IX, and compare that with Tuas Libenter, which was authored by the same pope 7 years earlier. I noted the time span to show, that which the pope decreed at V1, is what the Church always believed. These quotes are in regards to all those things Catholics are bound to believe.......
Tuas Libenter:
"Even when it is only a question of the submission owed to divine faith, this cannot be limited merely to points defined by the express decrees of the Ecuмenical Councils, or of the Roman Pontiffs and of this Apostolic See; this submission must also be extended to
all that has been handed down as divinely revealed by the ordinary teaching authority of the entire Church spread over the whole world, and which, for this reason, Catholic theologians, with a universal and constant consent, regard as being of the faith".V1 tells us:
"Wherefore, by divine and catholic faith all those things are to be believed which are contained in the word of God as found in scripture and tradition, and which are proposed by the church as matters to be believed as divinely revealed, whether by her solemn judgment or in her ordinary and universal magisterium".The two teachings are both saying the exact same thing. V1 tells us we are to believe all those things contained in her magisterium, TL tells us we are to believe "all that has been handed down..." ergo, all those things in the magisterium = "all that has been handed down..." "All those things handed down" are all those things that the Church has always taught.
This agrees with your other quotes on the magisterium being always infallible and explains why. This also explains why saying "the magisterium has gone off the rails" is altogether wrong, perhaps blasphemous.
So when we say "the magisterium teaches X", or "X is a teaching of the magisterium", what we are talking about, are teachings that the Church has always taught, i.e. "all that has been handed down..."