{HEAD ~ The flexible sheets} are attached to {TAIL ~ structural members}, that is, to purlins beneath the roof panels 
are attached to
{ HEAD ~ The flexible sheets } are attached to { TAIL ~ structural members } , that is , to purlins beneath the roof panels
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH