Stage Center Reverb... why 2 grounds?

[Triffid]

Hello, i recently breadboarded the state center reverb from ggg with much success.  I really like the sound, especially after implemented many of Mark Hammers tweaks found in these threads.  

When i build it though I just used 1 ground for everything.  I noticed that in the schematic at ggg there is a chasis ground and a curcuit board ground.  What is the reason for this?  As far as i can tell mine is functioning fine.

Thanks in advance

[Triffid]

So is this just for ease of wiring purpose so you don't have to bring everything back to the curcuit board?

[Mike Burgundy]

It's common practice to have all grounds meet at 1 point where the chassis is also earthed. I usually use the input jack's ground terminal for this. Power, circuit and chassis are grounded here.
If you consistently do this, it's a good way to avoid groundloops and other ground-related noise issues.

[Triffid]

So, really the 2 grounds are connected?