Currently series are limited to the Phanerozoic .
The ICS has stated its intention of subdividing the three systems of the Neoproterozoic ( Ediacaran , Cryogenian and Tonian ) into stages too .
Currently series are limited to the Phanerozoic , but the ICS has stated its intention of subdividing the three systems of the Neoproterozoic ( Ediacaran , Cryogenian and Tonian ) into stages too .