經濟壽命
economic life
或者：一項資產預計將通過一個或多個用戶使用的經濟週期; O（b）對預期由一個或多個用戶可以從資產獲得的生產或類似的單位數。
Either:the period over which an asset is expected to be economically usable by one or more users; o(b) the number of production or similar units expected to be obtained from the asset by one or more users.