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