wherein {HEAD ~ a nearest distance} between the first dummy metal and {TAIL ~ the second dummy metal} is more than a nearest distance between the third dummy metal and the fourth dummy metal, and 
between
wherein { HEAD ~ a nearest distance } between the first dummy metal and { TAIL ~ the second dummy metal } is more than a nearest distance between the third dummy metal and the fourth dummy metal , and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH