When open, {HEAD ~ a keyboard} having {TAIL ~ keys} that are apportioned between the housing and the base is accessible 
having
When open , { HEAD ~ a keyboard } having { TAIL ~ keys } that are apportioned between the housing and the base is accessible
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH