Hi @at9191, if the form start event is designed to trigger when the page loaded, you can add those relevant evar/event to the page view tracking rule, which you should have the page view tracking anyway, right? You can think like the page view tracking rule is the base, and you just adding more data.
You may use the customLink tracking action, s.tl, if the form start event happened after the page view event, such as trigger only if the user started filling the form with some onFocus event or onChange event on the form. In this case, you will use the s.tl as there is no page view tracking for you to ride on.