By using this method, a user can not only interact with the external program from within the editor environment, but can also create {HEAD ~ an editor file} that stores {TAIL ~ a listing} of the input and output provided to the external program 
stores
By using this method , a user can not only interact with the external program from within the editor environment , but can also create { HEAD ~ an editor file } that stores { TAIL ~ a listing } of the input and output provided to the external program
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH