My chinese alarm says red to + black to - blue to head lock where is the head lock & how do i connect it?

i have a cyclone 9966 motorcycle alarm to install to my motorbike it says red to (+) positive terminal (no probs) Black (thick) to -m neative (no probs) and blue to HEAD LOCK where is the head lock & how do i connect it. please help it will be much appriciated