Description: height of the centre of the inlet pressure gauge; Name: height of inlet pressure gauge 
Description: Height of the zero or centre position of the inlet manometer, or other point as defined by the manometer calibration ; Name: Height of the inlet manometer
Description: ten times the logarithm to the base 10 of the ratio of the sound power of a source, p, to a reference value, p0, expressed in decibels; Name: sound output level