MOTM

The "inner layers" are for a split ground plane (analog and digital ground, 
connected at
only 1 point via ferrite bead) and a *mostly* dedicated power distribution 
plane. There are
4 power signals: +5 digital (noisy), +5 analog (clean, from super whiz-bang 
Linear Tech regulator),
and the standard +-15V for the op amps. This is also my 'lifeline' routing layer 
if the top and
bottom are congested.

In most power cases, a 'trace' is not used but more of a "polygon" area. My CAD 
software
allows something called a "free-form copper pour" which means I define an 
outside boundary
and the CAD fills the interior with solid copper. In SMT ICs, the power is 
routed by a via dropped
into the power plane area.

I will have PDF of this next week. I'm still fitting all the parts in, just had 
an "Oh S*IT!" moment
on a connector orientation and have to re-place the analog section.

Paul S.