An umbrella structure according to the invention comprises a cover, {TAIL ~ a shaft}, a notch, a runner, {HEAD ~ main ribs} and stretchers 
An umbrella structure according to the invention comprises a cover , { TAIL ~ a shaft } , a notch , a runner , { HEAD ~ main ribs } and stretchers
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH