What is a 'cause of loss' form in commercial property insurance?

Commercial property insurance uses 'Cause of Loss' forms attached to the basic property policy to specify what causes of loss are covered. Three standard ISO forms: (1) Basic Form (CP 10 10) — limited named perils including fire, lightning, explosion, windstorm, hail, smoke, aircraft/vehicles, riot, vandalism, sprinkler leakage, sinkhole collapse, volcanic action; (2) Broad Form (CP 10 20) — Basic perils plus falling objects, weight of ice/snow/sleet, water damage from plumbing, certain collapse situations; (3) Special Form (CP 10 30) — open perils (all causes of loss except those specifically excluded). The Special Form provides the broadest coverage at the highest premium. Choice of form depends on the business's exposure to losses, budget, and the underwriter's willingness. The cause of loss form is one of several form 'modules' that make up a commercial property policy.