A skip down shift from {HEAD ~ a first shift position} to a second shift position is effected by way of a third shift position which is not used in {TAIL ~ a normal shifting} 
A skip down shift from { HEAD ~ a first shift position } to a second shift position is effected by way of a third shift position which is not used in { TAIL ~ a normal shifting }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL