Also, there are significant differences between “the Latin Mass” and the Mass of Blessed Pope John XXIII (often called “the Tridentine Mass”). Let us discuss some semantics.
Using the term “the Latin Mass” to refer to the Mass of Blessed Pope John XXIII is wrong because this incorrectly implies that the current Mass — the Missa Normativa or the Mass of Pope Paul VI — cannot be in Latin; this is wrong because any priest in any parish may (at least according to the original rules laid out by Pope Paul VI) offer the Mass in Latin. In fact, offerring the Mass in a language other than Latin is a matter of local episcopal and Vatican approval (the language and the texts used must be approved). Indeed, it was assumed that the Mass would continue to be offerred in Latin; that this was and is not the case (very few places offer the Mass of Pope Paul VI in Latin: the Mass is usually offerred in a vernacular) is an issue pertaining to the priests, laity, and episcopal conferences.
Using “the Tridentine Mass” to refer to what is properly “the Mass of Blessed Pope John XXIII” is not entirely accurate. One reason is because the Mass incorporates elements before the Council of Trent; another reason is because versions of the Mass existed prior to what Blessed Pope John XXIII promulgated. Just as Pope Paul VI abolished all missals other than what he promulgated, Blessed Pope John XXIII likewise abolished all previous versions of the Mass; and there is a long time indeed between the Council of Trent and 1962 (when Blessed Pope John XXIII issued the new liturgy). So the Mass of Blessed Pope John XXIII was/is not the Mass of the Council of Trent.
I find it interesting that Blessed Pope John XXIII issued a new liturgy, and so did Pope Paul VI after him (replacing what Blessed Pope John XXIII issued). Servant of God Pope John Paul II did not issue a new liturgy, and so far Pope Benedict XVI approved an old order of liturgy as an extraordinary celebration of the liturgy: he has yet to replace anything. I think the last major revision of the liturgy before Blessed Pope John XXIII (who reigned from 1958 to 1963) was by Saint Pope Pius X (who reigned from 1903 to 1914). After Saint Pope Pius X was Pope Benedict XV, then Pope Pius XI, then Venerable Pope Pius XII, and then Blessed Pope John XXIII. For frame of reference, the Council of Trent (“(Sacrosanctum) Concilium Tridentinum”) was from 1545 to 1563.