said {HEAD ~ sub step} in step further comprises determining {TAIL ~ survivability characteristics} of the current network topology 
comprises determining
said { HEAD ~ sub step } in step further comprises determining { TAIL ~ survivability characteristics } of the current network topology
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH