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.