From Church Militant:
In a Papal Rescript granted on June 5, 2017 ex Audientia Sanctissimi to the Cardinal Secretary of State Pietro Parolin, and just now released by the Vatican in the Acta Apostolicae Sedis, the Holy Father has raised to the level of "authentic Magisterium" both the private letter he wrote on September 5, 2016 to Bp. Sergio Alfredo Fenoy, the Delegate of the Buenos Aires Pastoral Region of the Bishops’ Conference of Argentina, and the Criterios Basicos para la aplicación del capitulo VIII de Amoris laetitia ("Basic Criteria for the Application of Chapter VIII of Amoris Laetitia"), issued on the same day by the bishops of the Buenos Aires Pastoral Region.
The Supreme Pontiff decrees that the two Documents that precede [this Rescript] are to be made known by publication on the Vatican website and in the Acta Apostolicae Sedis, as authentic Magisterium. From the Vatican Palace, on the 5th day of June in the year 2017. (emphasis added)Pietro Cardinal Parolin
Secretary of State