Tridentine Rite as extraordinary form: was never juridically abrogated

I posted this at Wikipedia:

Through his motu proprio Summorum Pontificum of 7 July 2007, Benedict XVI has enabled the use of the Tridentine Rite as extraordinary form of the liturgical celebration, as "a matter of a twofold use of one and the same [Roman] rite." He stressed that this Mass "was never juridically abrogated and, consequently, in principle, was always permitted."