A ‘diurnal chart’ is one where the Sun is located in the diurnal hemisphere: being above the horizon it denotes someone born in the day time and therefore belonging to the diurnal sect. A ‘nocturnal chart’ is one where the Sun is located in the nocturnal hemisphere: being beneath the horizon it denotes someone born at night and therefore belonging to the nocturnal sect. Many traditional techniques (parts, firdar, triplicites, etc.) require knowledge of whether the chart is diurnal or nocturnal to establish correct formulas and dignity rulerships.