At least a portion of {TAIL ~ the catch} is positionable around {HEAD ~ at least a portion} of the tab 
At least a portion of { TAIL ~ the catch } is positionable around { HEAD ~ at least a portion } of the tab
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH