How to use variables in a paramset?

Hi,

I am trying to use a paramset in order to change the timestep during simulation. I am trying something like this:-

tran tran stop=trantime errpreset=conservative write="spectre.ic" writefinal="spectre.fc" annotate=status maxiters=5 paramset=pset1

pset1 paramset {

time                                     maxstep

0                                          1e-6

pldo_ready_time                  200e-12

}

Where pldo_ready_time is a variable that is dependent on the corner I am simulating. How do I incorporate a variable as a time parameter in the paramset. Spectre errors out and doesnt allow me to use a variable pldo_ready_time.

Thanks,

Sunny