What is the ruling if the indeterminacy of the dowry exceeds that of the customary equivalent dowry (mahr al-mithl)?

Primary text

If the indeterminacy of the dowry is greater than the indeterminacy of the customary equivalent dowry—such as specifying a garment, an animal, or an attribute of the item, or something contingent on a future acquisition (like what is earned in the year)—the specification is invalid. This is because there is no means to determine the median value, rendering its fulfillment impossible.