ECD	Effective case depth
GF	Grinding fluid
HPGQ	High-pressure gas quenching
HV	Hardness in the Vickers scale
LPC	Low pressure carburising
MQL	Minimum quantity lubrication
PSD	Power spectral density
TCT	Thermochemical treatment
WET	Flood method using water emulsion as coolant
ae	Working engagement (depth of cut), mm
ad	Dressing allowance, mm
id	Number of dressing passes
l	Evaluation width, mm
lt	Tracing length, mm
ln	Evaluation length, mm
lr	Sampling length, mm
ns	Grinding wheel rotational speed, rpm
P	Supply air pressure (MQL method), MPa
rtip	Stylus tip radius, μm
Rp	Value of the highest peak of the profile, μm
Rv	Value of depth of the lowest valley of the profile, μm
Rz	Maximum height of the roughness profile, μm
Sk	Core roughness depth, μm
Spk	Reduced peak height, μm
Ssk	Skewness, μm
Str	Texture direction
Sz	Maximum height of surface, μm
Qd	Dresser weight, kt
QMQL	MQL flow rate, mL/h
QWET	Conventional GF flow rate, L/min
vfd	Axial table feed speed during dressing, mm/min
vs	Grinding wheel peripheral speed, m/s
vsd	Grinding wheel peripheral speed during dressing, m/s
vt	Tracing speed, mm/s
vw	Workpiece peripheral speed, m/min
λc	Long-wave profile filter, mm