Useful life 1 : May be expressed as either: (a) The period over which a depreciable asset is expected to be used; or (b) The number of production or similar units (i.e. intervals, cycles) that is expected to be obtained from the asset
Ministry of Business, Innovation and Employment, Glossary of terms and acronyms, Wellington, New Zealand 2010. http://wwwsosh.govt.nz/resources/glossary-u.shtml, (Occupn Hlth and Sfty - Brit) {530}