On the left side of the bike, near the side stand is a 3wire loom with a plug. That goes to the side stand position switch. If the bike has a "Sidestand not up" indication, the engine will cut out when put into gear. Police bikes use this function (via a switch) to allow the bike to be left running with all the lights on if needed. It prevents a "Wally" jumping on the bike and riding off.
I made up my own to immobilise the bike..