Parameters (R? / P?)
Press the settings button to enter the settings menu
Press the down arrow button to scroll down to the Parameter setting 
line. Press the        to toggle between the two ISO 4287 parameter 
options available to display – Roughness (R) or Primary (P). Press the 
tick button to accept the setting and exit the settings menu. Either 
selection will display all the parameters available for that particular 
option on the results screen.
ISO 4287 
Roughness 
parameters (R)
ISO 4287 
Primary 
parameters (P)