You are about to create a new control.  Enter the code of the control and click OK.   The code can be from 1 to 3 digits or letters. 

Even if this "control" is really a start point or a finish point, you need to assign it a code.

Use codes from the predefined set of punch patterns on this PC

If you check this box, Condes will try to find an unused control code from among the set of punch patterns stored on this PC. You can configure the set of codes by using the Predefined Controls' Punches page in the Standard Settings for this PC pages

For more on this topic, consult "How to use the same punch patterns for more events".