A quick definition of claimant:

A claimant is someone who says they have a right to something, like land or things. They might say it officially. An occupying claimant is someone who says they have the right to land because they have made improvements to it. This can happen if the land doesn't actually belong to them.

An occurrence is something that happens, like an accident or event. If it causes someone to get hurt or damages their things, it might be covered by insurance. An occurrence policy is a type of insurance that covers these kinds of things. The occurrence rule says that if someone does something wrong, like breaking a contract, the time limit for suing them starts when they did the wrong thing, not when the person who was hurt finds out about it.