According to the manual, KI stands for KILL, that is a command that everyone uses sooner or later when programming. I use it to reset the program stack so I can download the same program.
KILL
Function
Initializes the stack of the robot program.
Explanation
If the program is stopped by PAUSE instruction, ABORT command, or an error, the program
stack is kept at the current status. The KILL command is used to initialize the stack. Once the
KILL command is used, the CONTINUE command is ineffective, since there is no program on
the stack.