The first had to written by a Prophet, Apostle or someone under the authority of an Apostle, like Mark and Luke, who themselves were not Apostles. It had to be written in Koine Greek and Hebrew and be inspired by God, which is to say that the writings were either prophetic or refers to a prophesy in context without contradiction.
During the counsel of Trent, which was held between 1545 and 1563 in Trento (Trent) and Bologna, northern Italy, and was one of the Roman Catholic Church's most important ecumenical councils and prompted by the Protestant Reformation, including scripture, the Biblical canons, sacred tradition, what constitutes original sin, justification, salvation, the sacraments, the Mass and the veneration of saints the whole bit.