For point features, the centre of the circle shall be the centre of the symbol.
For line and area features, the centre of the circle shows the precise position of the control marker. Controls shall only be placed on points that are clearly identifiable on the map.
Sections of the circle should be omitted to leave important detail showing.
Footprint: 75 m in diameter.
Colour: purple (lower purple).
The definition of this map symbol was updated on 20.01.2020: Precise definition of colour: upper and lower purple.