Prerequisite:

A prerequisite is a more defined set of conditions for the event to be triggered. Only when the Event properties and prerequisites are met that the action can be triggered. The prerequisite consists of...

To reveal an event prerequisite content click on the (-) and (+) box on the left of blue 'Prerequisite' word in the event to reveal a drop down list.

To create a new prerequisite click on the red 'Click here to add a new prerequisite...' sentence under the blue 'Prerequisite' in the selected event and a create 'New Prerequisite Wizard' will appear guide you through the steps. Click on the 'Next' button to set the prerequisite type.