A counter counts {HEAD ~ a first time duration} commencing from the last transition to {TAIL ~ inspiration} and whereby if the first time duration elapses before a transition to expiration is detected, the controller initiates the supply of a given expiratory pressure 
commencing to
A counter counts { HEAD ~ a first time duration } commencing from the last transition to { TAIL ~ inspiration } and whereby if the first time duration elapses before a transition to expiration is detected , the controller initiates the supply of a given expiratory pressure
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH