Thereafter follow those honoured with different grades of the order, divided into five levels: the highest two conferring accolades of knighthood and all having post-nominal letters and, lastly, the holders of the Royal Victorian Medal in either gold, silver or bronze. Foreigners may be admitted as honorary members, there are no limits to the number of any grade, and promotion is possible. The styles of knighthood are not used by princes, princesses, or peers in the uppermost ranks of the society, save for when their names are written in their fullest forms for the most official occasions. Retiring Deans of the Royal Peculiars of St George's Chapel at Windsor Castle and Westminster Abbey are customarily inducted as Knights Commander; clergymen appointed to the higher levels of the Royal Victorian Order do not use the associated styles, however, and honorary members are not permitted to hold them at all.