海龟通道线

AA:HHV(H,N1),COLORRED;

BB:LLV(L,N2),COLORRED;

AA1:=CROSS(C,REF(AA,1));

AA2:=FILTER(AA1,3);

BB1:=CROSS(REF(BB,1),C);

BB2:=FILTER(BB1,3);

DD:(AA+BB)/2;

DRAWICON(AA2,L,4);

DRAWICON(BB2,H,5);