{TAIL ~ This source} may include an airstream entrained with {HEAD ~ particles} which is discharged into the space through an orifice; the airstream diverging as it enters the space 
{ TAIL ~ This source } may include an airstream entrained with { HEAD ~ particles } which is discharged into the space through an orifice ; the airstream diverging as it enters the space
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH