The insured sum (also: insured capital) is the maximum amount which covers the policyholder in case of claim.
Limited insured sum: An insurance at most covers the agreed insured sum in case of claim.
If the amount of loss exceeds the insured sum, the policyholder has to pay the difference. This is called underinsurance.
Unlimited insured sum: In the case of an unlimited insured sum the amount of loss is irrelevant.
