Panasonic KX-TD500 System Reference Manual page 1373

A. Preparation
1.00 Outline of Local Mode
Attendant Console Local Mode is used to test the
console by itself.
Attendant Console becomes off-line and Local
Mode when the Local Switch on the right side of
the Console is turned on.
The operator at Attendant Console can utilize the
Local Diagnosis mode on local mode.
14-A-1