Altar cards were not used before the sixteenth century, and even today they are not used when a Bishop celebrates the traditional Mass, because he reads the entire Mass from the Pontifical Canon. When Pope St. Pius V restored the Missal, only the card at the middle of the altar was used, and it was called the "Tabella Secretarum". The left card was added first, and then the right one was added for the sake of symmetry.