Bull, Single (Or Semi)
Between the time of the pope’s election and coronation. the bulla or seal attached to a document issued by him has an impression on one side onlv- viz., the effigies of Sts. Peter and Paul, the reverse being without any stamp. This is called a single or semi bull. After consecration the name of the pope and the date of his reign are stamped on the reverse; this makes the double bulla.