a unit of <#stamp=stamps> cut from a full <#sheet>, either for assembly into <#booklet=booklets>, or for individual sale at post offices. Sheets intended to be cut into <#pane=panes> for assembly into booklets will each produce a large number of relatively small panes, typically 30, 40, or 60. Sheets intended for division into panes to be sold individually are divided into fewer but larger panes. Many early sheets consisted of only two panes. Most twentieth century sheets consisted of four panes. Modern sheets consist of six or more panes. Panes are commonly, but inaccurately, referred to by the public as sheets.