§1. The proper law of each society determines the admission, probation, incorporation, and formation of members.
§2. In what pertains to admission into a society, the conditions established in the cann. 642- 645 are to be observed.
§3. Proper law must determine the manner of probation and formation, especially doctrinal, spiritual, and apostolic, adapted to the purpose and character of the society, in such a way that the members, recognizing their divine vocation, are suitably prepared for the mission and life of the society.
Source: Code of Canon Law (Vatican.va)