RobotStudio event

IRC5 contactors K1 & K2

I am a newbie studying ABB robots.  I know K42 and K43 are motor on contactors.  What are K1 & K2?  I am quoting the following directly from a ABB manual.    "The motor contactors K1K42and K2K43 in the controllerdrive module can operate with external equipment if external relays are used."     Thank you.