In the links you posted (2 comments up) there is a PID controller. Out of the difference block the signal splits 3 ways. In Simulink that junction would just be a round dot where the lines meet. In most diagram editors that junction would probably have 5 lines connected to it. In my scheme there would be one horizontal line right through it and one vertical line. There would also be 2 short horizontal lines connecting the vertical line to the P and D blocks. In my scheme you could drag the D block up to the top above the P (D,P,I) and the junctions would change (because they're locations are computed) even though the topology has not. I never did a full implementation. email me at gmail if you want a better explanation or a quick drawing.