[rules-users] Rete diagram legend - what do all the colors mean?...

Hi, I was trying to make some sense out of Rete Diagram for my rules (DROOLS 3.1M), and one of the questions I have is what all these colors mean? There are red, blue, yellow, green, orange, white, cyan and black circles.... I might be wrong, but I think this should mean something! Also, I noticed that by default the diagram is displayed in 'layers' of dots. In my case I have 7 layers, the top one being the 'root' I assume (single white circle). The 'widest' layer is the middle one - the forth layer. So, generally the diagram has a diamond shape. I wonder if one can use this kind of visual information to make a rough estimation/assumption on how efficient his rules/constraints are, some hints into optimization, etc.... Thanks, Vlad