timestep parameters -- repeat this line for each time group
example:

(a)    (b)  (c)
50.0   1.0  0.5

(a) use present time step size until this time is reached
(b) implicit/explicit parameter; 0<alpha<1; usually set to 1.0
(c) time step size

(a) and (c) are in the natural time units of the problem, and (b) is dimensionless.