ACF autocorrelation function	Sa arithmetic mean height Sa, µm
ACF-CSM Autocorrelation Function Centre-Shape Method	Sal auto-correlation length, mm
F-operator removes F-surface from measured data	Sbi surface bearing index
F-surface form surface	Sci core fluid retention index
FFTF Fast Fourier Transform Filter	Sdq root mean square gradient
FOD free of dimple detail	Sdr developed interfacial areal ratio, %
GF Gaussian filter	Sk core roughness depth, µm
HFNS high-frequency noise surface	Sku kurtosis
MF median filter	Sp maximum peak height, µm
PSD power spectral density	Spc arithmetic mean peak curvature, 1/mm
PSM Profile Spline Method	Spd peak density, 1/mm2
RGF robust Gaussian filter	Spk reduced summit height, µm
S–F surface a surface after S- and F- filtering	Sq root mean square height, µm
S-operator removes S-surface from measured data	Ssk skewness
S-surface short-wavelength noise surface	Std texture direction, °
SF spline filter	Str texture parameter
TTP treatment trace profile technique	Sv maximum valley depth, µm
VEM valley excluding method	Svi valley fluid retention index
	Svk reduced valley depth, µm
	Sz the maximum height of surface, µm