{HEAD ~ A gap} is defined between {TAIL ~ the counter tool} 14 and the sonotrode 20 for passage of the material web 12 
{ HEAD ~ A gap } is defined between { TAIL ~ the counter tool } 14 and the sonotrode 20 for passage of the material web 12
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH