strict digraph ductNet {
        graph [nodesep=0.6, ranksep=1.0];
        node [shape=box, style=filled, fillcolor=lightblue];
        edge [color=red, penwidth=2];
        rankdir=TB;
        { rank=min; MB01; }
	MB01 -> MB02;
	MB02 -> MB03;
	MB02 -> MB04;
	MB04 -> MB05;
	MB04 -> MB06;
	MB06 -> MB07;
	MB06 -> MB08;
	MB08 -> MB09;
	MB08 -> MB10;
	MB10 -> MB11;
	MB10 -> MB12;
	MB12 -> A101;
	A101 -> A102;
	A101 -> A103;
	A103 -> A104;
	A103 -> A105;
	A105 -> A106;
	A105 -> A107;
	MB12 -> MB13;
	MB13 -> MB14;
	MB13 -> MB15;
	MB15 -> MB16;
	MB15 -> MB17;
	MB17 -> A201;
	A201 -> A202;
	A201 -> A203;
	A203 -> A204;
	A203 -> A205;
	A205 -> A206;
	A205 -> A207;
	MB17 -> MB18;
	MB18 -> MB19;
	MB18 -> MB20;
}