Latin Mass

There are several approaches to the Latin Mass.

The first is the Tridentine Mass, which actually is the Mass as said back to the time of Saint Gregory the Great.  This has two basic calendars:

The pre-1955 calendar, which is accepted by most of the Sedevacantists who judge that the 1955 Holy Week is illegitimate.

The 1955 calendar, which is accepted by the CMRI, which is actually the proper position for a Sedevacantist, as it is totally obedient to the last person they consider Pope.

The John XXIII Mass, which uses the calendar promulgated by Rubricarum Instructum, which is based in part on Modernist principles.  This Mass also has a change to the Canon,which has not been touched since the time of Saint Gregory the Great, who inserted one phrase.  Saint Joseph has been inserted to this Canon, which makes it no longer the Tridentine Mass.  In addition to being used by the Society of Saint Pius X and the Resistance, it is also used for the Extraordinary Form of the Conciliar Church.