They are sometimes included in insurance policies covering exposures that may occur over long periods, triggering coverage under multiple policies. They stipulate that, in such an event, only one policy limit or one deductible (rather than the limit or deductible under each policy) applies to the occurrence. Anti-stacking provisions (or stacking provisions) may be addressed in a state's motor vehicle insurance statutes with respect to uninsured motorists (UM)/underinsured motorists (UIM) coverage. These provisions vary widely from one state to another; and where a state's legislators or court system has addressed the issue, the UM/UIM endorsements in the state are often modified to reflect the state's stance on the issue.