Fn

Key Fn in Scheduled Number Is Inside refers to the base predicate function ƒ₁ mentioned in Scheduled Number Is Inside
Expects an object of type Number Is Inside
This function applies on the first date d'₁ of the dates d'₁ , d'₂ , ... implied by the entry in key Step Up Schedule
On later dates, the applicable function may be different if so instructed by the optional entries in keys Left Step Up and Right Step Up