Maximum M5 area of merged low density windows must follow item (1) and (2).
The definition of low density window: window size 10um*10um, step size: 5um, density <1%
(1) Maximum area of merged low density window <= 6500um2, except merged low density windows width <= 30um.
(2) Maximum area of merged low density window <= 18500um2.
DRC only check the region with width of (checking window NOT above excluding region) >= 5um
DRC doesn't check INDMY region.