Without a defined standard of service (SoS) there is no means of knowing what service level customers can expect, and no effective control on the whole-life cost. With a clearly defined SoS, the asset manager is clear about how success or failure will be measured, and the customer understands what to expect in return for the expenditure on the asset system. There are two parts of a well-defined Standard of Service: the minimum condition grade (CG) and a specified performance standard. By managing against a defined SoS, which couples the performance specification with the condition grade as a measure of reliability, Asset Managers avoid the considerable complication of trying to optimize maintenance over short timeframes, or the need to determine the outcome or benefit associated with each individual intervention. Asset Management takes a whole-life cost approach to decisions regarding operation, maintenance, refurbishment and replacement of assets.