Pspice maximum step size question

Hi there,

I am doing traisent analysis in ORCAD Pspice 16.3. Two questions:

1. In "Simulation Setting" dialog box, the "Maximum step size" is usually defualt to be blank ,then what is the default step value set by cadence?

2. In some other prject, I've seen step size set as {SCHEDULE(0,1000ns,2.5m,25ns,6m,15ns)}, what soes this "schedule" function means?

Thanks a lot !