Assume that the current model has four parameters:
XSPEC> steppar 3 1.5 2.5 ! Step parameter 3 from 1.5 to 2.5 in
steps of .1.
XSPEC> steppar log ! Repeat the above, only use
multiplicative steps of 1.0524.
XSPEC> step nolog 2 -.2 .2 20 ! Step parameter 2 linearly from -.2
to .2 in steps of 0.02.