The Council of Sardica (343) mentions the lectorate alone as obligatory before ordination to the diaconate. The obligation to receive all four minor orders appears to date only from a time when they ceased to indicate exercise of an actual function. Even in the early years of the 20th century, no minimum age, other than that of the "age of reason", was laid down for receiving minor orders. However, the 1917 Code of Canon Law laid down that nobody was to be given clerical tonsure, which had to be received before minor orders, before beginning the regular course of theological studies. Before the entry into force of that Code, it was an almost universal custom to confer all four minor orders at one time, since the bishop was authorized to dispense from the rule that each order had to be exercised for some time before reception of the next highest order. Today, as indicated in the 1983 Code of Canon Law, anyone who is to be ordained to the diaconate must already have received the ministries of lector and acolyte and exercised them for a suitable period, with an interval of at least six months between becoming an acolyte and becoming a deacon.