* nested .dc: Id vs Vgs for a family of Vds
.model NM NMOS(level=1 kp=200u vto=0.5)
Vd d 0 DC 1
Vg g 0 DC 0
M1 d g 0 0 NM w=10u l=1u
.dc Vg 0 2 0.5 Vd 1 2 1
.control
  run
  let id = i(vd)
  print id[3]        $ Vgs=1.5 on the first Vds curve
.endc
.end