generating, in the computing device, an identifier that is associated with {HEAD ~ the lock} on {TAIL ~ the first feature instance} and returning the identifier to the client 
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generating , in the computing device , an identifier that is associated with { HEAD ~ the lock } on { TAIL ~ the first feature instance } and returning the identifier to the client
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH