The scope of class registration in these cases depends on the characteristics of each individual offshore unit. For an FPSO for example, the hull and mooring systems are generally registered in accordance with classification society rules, while for the topside facili-ties, classification is used only to certify the minimum safety standards for key equipment. Although class registration is not required for many offshore facilities, classification societies are often re-quested to examine designs in accordance with other safety standards such as specific industry standards and oil company specifications which differ from standard classification requirements.