Tonepad PCB layout color guide

[studiostud]

So here's a quick question... Tonepad's layouts are fantastic and one reason I love them is because the different circuit paths are color coordinated.  I just had a quick question.  I understand that the blue path is the audio signal path, the red path is the +9V power path and the green path is the ground path.  But what is the orange path?  And what does it mean when you see solder points that are gray?

[John Lyons]

I'd have to look but possibly voltage reference and or bias for the op amp.

john