After all the elements of a stimulus are defined, select the comments field. The “>” arrow now appears because all of the necessary fields are assigned. When the corresponding “Fire” button in the first column is clicked, the T1CK pin will toggle its state, pin INT0 will become high regardless of what it was previously, and pin RA6 will pulse low for 2 cycles then go back to high. If pin RA6 was already low, then nothing will happen.