threshold determining means for determining {TAIL ~ a velocity threshold value} functionally related to {HEAD ~ said crash displacement value}; and 
threshold determining means for determining { TAIL ~ a velocity threshold value } functionally related to { HEAD ~ said crash displacement value } ; and
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH