The message {TAIL ~ “CAL}” appears in the display 26, prompting {HEAD ~ the user} to calibrate 
The message { TAIL ~ “ CAL } ” appears in the display 26 , prompting { HEAD ~ the user } to calibrate
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH