How to read TC slip?

[dieselfreek26]

Every so often I switch my gauges on my DD to monitor different aspects of my engine to keep an eye on as much as possible... I uploaded to the 300 EL tune now that its getting warmer out, and Im just curious what I should see on the read-out for TC Slip. I know when your stopped and in Park, the rpms on the screen should match your tach.