Determining prepfold P and Pdot step sizes

[k-perez]

I'd like to understand the exact range over which prepfold conducts a search on. When running prepfold, a grid search is generated across DMs, periods, and p-dots (Example from output file: > Searching 385 DMs, 257 periods, and 257 p-dots...)

I understand the step size and factor for each (DM, P, and P-dot) varies depending on what flag is being used (-coarse, -fine, or none). The DM step size is simple. But what exactly does a step size of 1,2,3, etc. mean for P and P-dot? In the example above, say, for a period of 10 seconds, and a pdot of 3e-11, what would the range of the 257 periods and p-dots be? What are the units of the step sizes? Thank-you.