The churches are divided into two parts. The forward part is for the congregants and the rear part is for the clergy. The division between them is an icon screen, called an "iconostasis", with a double-door entrance. The number of tiers of icons and the level of ornateness varies, of course, from church to church. As a general rule, these icons strictly followed models and formulas defined by Byzantine art, when the Greek Orthodox church dominated (before the Russian Orthodox church split off), and are mostly painted on wood with gold leaf decoration.