If there is no existing lock on F2, a lock on the additional feature instance F2 is set 608 as requested, and the identifier {HEAD ~ TID1} owned by the session S1 is associated with the lock L1 and {TAIL ~ L2} on feature instances F1 and F2, respectively 
is associated with
If there is no existing lock on F2 , a lock on the additional feature instance F2 is set 608 as requested , and the identifier { HEAD ~ TID1 } owned by the session S1 is associated with the lock L1 and { TAIL ~ L2 } on feature instances F1 and F2 , respectively
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 HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH