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