System to fix premiums for fire insurance risks. The insured pays in proportion to: (a) the value at risk; (b) the degree of hazard present. The premium is the rate per cent multiplied by the sum insured. The rate reflects: (i) the trade classification, groupings of trades or sections of trades, broadly similar in experience in terms of the incidence and severity of fires; (ii) discrimination, i.e. differentiation of individual risks within a specified class due to particular features present in any individual risk; (iii) experience, meaning the relationship of losses to premiums in a given class over a period of years.