 For Papal Bulls, legal instruments almost entirely for important matters, the seal was stamped in wax or lead, seldom in gold, enclosed in a case, and fastened to the document by a cord.For Briefs, instruments used as a rule in matters of less importance, the seal was stamped upon the document in wax.Curial letters ("litterae curiales" or "litterae de curia") denoted particularly letters of the popes in political affairs.