In {HEAD ~ effect}, the flap and {TAIL ~ base member} define a receptacle within which the instrument can be retained 
In { HEAD ~ effect } , the flap and { TAIL ~ base member } define a receptacle within which the instrument can be retained
OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH