Alternatively, {HEAD ~ scenarios} may be provided by {TAIL ~ a user} or obtained from another source 
provided by
Alternatively , { HEAD ~ scenarios } may be provided by { TAIL ~ a user } or obtained from another source
OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH