Function or combination of functions of an item that is considered necessary to provide a given service.
Source: API STD 689, Collection and Exchange of Reliability and Maintenance Data for Equipment, First Edition, July 2007. Global Standards
Function, or combination of functions, of an item that is considered necessary to provide a given service.
Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global Standards