{TAIL ~ The flow surface} includes {HEAD ~ a first portion} and a second portion extending downstream from the first portion 
{ TAIL ~ The flow surface } includes { HEAD ~ a first portion } and a second portion extending downstream from the first portion
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH