Valid certificate means certificate issued by an independent party (including any member of the classification society) for a fixed time period.
Source: Guidance Notes on Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, Oil Industry Safety Directorate (India), 2012. Regulatory Guidance
A certificate that has been issued directly by a Party to a relevant convention or on its behalf by a recognized organization and contains accurate and effective dates meets the provisions of the relevant convention and to which the particulars of the ship, its crew and its equipment correspond.
Source: IMO resolution A.1052(27), Procedures for Port State Control, 2011, 201 December 2011, International Maritime Organization. Regulatory Guidance