This parameter is used to specify the method used to sample all steady-state
  norms associated with this option. See 
  Steady-state detection
  for more information regarding steady-state norm definitions.
Set SAMPLING=PLANE BY PLANE to calculate the steady-state norms as each plane of elements
  crosses the exit plane. This method should be used only for non-Eulerian
  analyses with uniform planes of elements sequentially passing the exit plane. 
Set SAMPLING=UNIFORM to calculate the steady-state norms at an interval defined by
  the time required for material to flow through an element of average length.
  This interval is determined at the beginning of the step and remains constant
  throughout the step. This method should be used only for analyses with material
  flowing in and out of Eulerian boundary regions in the primary direction.