gEDA-user: 3 questions on a 4 layer board

[DJ Delorie]

> Turns out that for the purpose of impedance a power plane is exactly
> the same as a ground plane.

That's true unless you have a split power plane.

The whole field of high speed PCB layout is much more complex than is
warranted on this list, which is why I made a sweeping generalization.
I think for people who don't know better (and don't need to know
better), keeping ground near most of the signals is a simple rule that
will cover most of the problems.