2. There are three kinds of apostolical rescripts, the brief, the signature, and the bull, which last is most commonly used in legal matters. Bulls may be compared to the edicts and letters-patent of secular princes: when the bull grants a favor, the seal is attached by means of silken strings; and when to direct execution to be performed, with flax cords. Bulls are written in Latin, in a round and Gothic hand. Ayl. Par. 132; Ayl. Pand. 21; Mer. Rep. h. t.