In Altium Designer we can specify the electrical clearance between all sort of objects, esepcially between nets and between net and other objects.
Often we have to specify rules that specify minimum distance between one net and another as a function of the net width. This has confused me a bit. If two nets have different widths, and we have specified clearance based on net width (e.g clearance value is twice the net width), which of the two will take precedance?
There is a bigger issue. The track width of impedance controlled tracks is determined automatically by the Altium designer through input from the impedance profile. When such a track moves from one layer to another, the width of the track will change, due to law of physics, in order to ensure the same characteristic impedance. Now the question arises here, how does one automatically specify to Altium designer, to use the dynamic width of the track that depends on which layer it is on as it travels from sourch to destination, for the clearance rule? In other words, since the width changes as the signal travels from one layer to another, if the clearance is specified as twice the track width, Altium will need to re-evaluate the value of clearance since the clearance is a function of the PCB track width.
I hope my question is clear. I am not sure how Altium deals with this. I think that for things like DDR tracks, there must be some sort of special mechanism to assign rules that make the whole task easier. The design rules concept in Altium Designer is neat but I fear that for complex designs, it might become a big mess (containing query langauge instructions) that is difficult to navigate for normal humans.