In this scheme (called asynchronous time scheme), there is no relationship between the simulation step and incrementing time.
Several steps can be performed at the same time without advancing the time and time may be advanced without any steps occurring.
Therefore, the Simulation Tool differentiates between the role of step and time during the simulation. In the normal flow of simulation, time is advanced when the system is in a stable status.
In the step-independent time scheme, time is advanced after each superstep and not after each step as in the step-dependent scheme.