A time step consists of granularity and the number of steps. For instance, you can specify yearly steps by settings the granularity to Years and the number of steps to 1. Half-yearly steps can be specified by setting the granularity to Months and the number of steps to 6.
Years
Months
granularity
TimeGranularity
months
step
integer
The granularity of the time steps can take one of the following values.
millis
seconds
minutes
hours
days
years
{ "granularity": "months", "step": 1 }