{HEAD ~ A camera mountable arm} includes {TAIL ~ a first segment}, a second segment, and a third segment 
includes
{ HEAD ~ A camera mountable arm } includes { TAIL ~ a first segment } , a second segment , and a third segment
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH