On 28 February 1476, Pope Sixtus IV, authorized those dioceses that wished to introduce the feast to do so, and introduced it to his own diocese of Rome in 1477, with a specially composed Mass and Office of the feast. With his bull Cum praeexcelsa of 28 February 1477, in which he referred to the feast as that of the Conception of Mary, without using the word "Immaculate", he granted indulgences to those who would participate in the specially composed Mass or Office on the feast itself or during its octave, and he used the word "immaculate" of Mary, but applied instead the adjective "miraculous" to her conception.
What document made the authorization official ?
with a specially composed Mass and Office of the feast. With his bull Cum praeexcelsa of 28 February 1477