Involves the question of "how much" each of two or more policies
covering a risk, which sustained a loss, will contribute to that loss. In
workers compensation insurance, it is the division of liability for an
occupational illness among various entities. Usually this means dividing it
among a group of employers in whose employment the employee was exposed to the
conditions that contributed to the illness. It can also mean division of
liability between an employer and a fund, such as a second injury fund, that
pays for the portion of a claim attributable to preexisting conditions.