Study of armorial bearings applied to seals and coats-of-arms of religious corporations and to emblems attributed to particular saints. The earliest of such ecclesiastical seals bore the device of a bishop or abbot, and by the fourteenth century English religious houses were ordered to have a common seal. It developed later into an impersonal coat-of-arms for each community. The miter, the crosier, and hat appeared as emblems in the fourteenth century, and by the seventeenth century the cardinal's hat was almost universal. The rank of the prelate was shown by the number of tassels. The heraldic miter is now placed above the other symbols by those entitled to wear it. Another external ornament to the shield is the crosier, a sign of episcopal dignity. also used armorially is the cross: two-barred for the primate, and treble traverse on the papal cross. The bourdon, or knobbed staff, often appeared behind the shield or a prior or prioress. The Armenians are the only non-Catholic Eastern ecclesiastics who use heraldic devices. The arms of Vatican City are a tiara above two crossed keys, gold on red.