W	Pit width
L	Pit length
d	Topography offset distance
hs	Slider height
hp	Pit height
Sa	Arithmetical mean height
Sq	Root mean square height
Sz	Largest height
Sp	Largest peak height
Sv	Largest pit height
Ssk	Skewness
Sku	Kurtosis
Sxp	Difference in height between the 2.5% and 50% material ratio