Battery Snap?

[playpunk]

Does the battery snap in the standard wiring diagram just function as an isolated ground?

Please advise.

[nzCdog]

Sorry playpunk, but I don't really understand your question? 
The battery snap is the part which the 9V battery connects to, both + and - terminals

[rullywowr]

The ground on battery (and snap) is connected to the common ground on the pedal.  The positive lead gets switched out for the adapter lead when an adapter is plugged in.

[jimilee]

The ground on battery (and snap) is connected to the common ground on the pedal.  The positive lead gets switched out for the adapter lead when an adapter is plugged in.

if I'm not mistaken,  its not the common ground, its a third tab on a stereo jack, and plugging it in completes the circuit. If you use a common ground and not a stereo jack, it will run your battery down regardless of if you're using it out not. Correct me if I'm wrong.