01. Parikamma-nimitta.
The preparatory sign, this is the perception of an object at the beginning of concentration.
02. Uggaha-nimitta.
The acquired sign, in which the mind reaches a mild degree of concentration with an unsteady or unclear image.
03. Patibhaga-nimitta.
The counter-sign, where a clear and static image is a sign of pure concentration.
