{HEAD ~ The overhead traveling vehicles} travel along a travel rail provided near {TAIL ~ a ceiling}, and the number of the overhead traveling vehicles is, e.g., more than one hundred 
{ HEAD ~ The overhead traveling vehicles } travel along a travel rail provided near { TAIL ~ a ceiling } , and the number of the overhead traveling vehicles is , e.g. , more than one hundred
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH