For example, a keyboard 34 may be used for {HEAD ~ interaction} with {TAIL ~ the user}, as may a mouse 36 
with
For example , a keyboard 34 may be used for { HEAD ~ interaction } with { TAIL ~ the user } , as may a mouse 36
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH