The categorisation “mission critical” is used by Government in relation to departmental projects. The definition of mission critical programmes or projects is published in the NAO report ‘Delivering Successful IT enabled Business Change’ (November 2006) and is used to define those that are (A) essential to the successful delivery of a major legislative requirement, a PSA target, or a major policy initiative announced and owned by the Prime Minister or a Cabinet Minister; or (B) if the programme or project is not successful there are catastrophic implications for the delivery of a key public service, national security or the internal operation of a public sector operation.