Comment 12 for bug 1787275

I'm not asking for area-based clearance or anything complex. I'm asking for a very simple conditional when doing clearance checks on a track:

1) Minimum clearance from a DP leg to a *track* for the other DP leg is the netclass DP spacing
2) Minimum clearance from a DP leg to a *pad* for the other DP leg is the netclass track clearance
3) Minimum clearance from a DP leg to *any track or pad not part of the DP* is the netclass track clearance

Is this difficult to implement? Do you believe any of these rules are incorrect behavior? (And if so, how much high-speed digital layout experience do you have to based your claim on?)

For example, in my example board the DP legs should be kept 250 um apart from each other, however it should be legal for one leg to get within 125 um of a connector pad for the other DP leg, or 125 um of any other track. Later on we can add more advanced design rules to limit this incidental contact to prevent excessive coupling to non-DP tracks, but for the moment I believe it's important for the router to err on the side of being permissive rather than prohibitive.

It's a lot easier to manually re-route a few tracks to ensure sufficient clearance for EMC reasons, than to change design rules or do other awkward things because KiCAD refuses to let you escape a BGA, connector, etc.