Altarpiece two, three, and multiple panels respectively. In the thirteenth century each panel was usually surmounted with a pinnacle, but during the Renaissance, single panel, or "pala", altarpieces became the norm. In both cases the supporting plinth, or "predella" often featured supplementary and related paintings. If the altar stands free in the choir, both sides of the altarpiece can be covered with painting. The screen, retable or reredos are commonly decorated. Groups of statuary can also be placed "on" an altar. A single church can furthermore house several altarpieces on side-altars in chapels. Sometimes the altarpiece is set on the altar
Early Netherlandish painting time. That hinged works could be opened and closed served a practical purpose; on religious holidays the more prosaic and everyday outer panels were replaced by the lush interior panels. The "Ghent Altarpiece", completed in 1432, had different configurations for weekdays, Sundays and church holidays. The first generation of Netherlandish masters borrowed many customs from 13th- and 14th-century Italian altarpieces. The conventions for Italian triptychs before 1400 were quite rigid. In central panels the mid-ground was populated by members of the Holy Family; early works, especially from the Sienese or Florentine traditions, were overwhelmingly characterised by images of the enthroned