Barrier whose proper deployment has been substantiated through a postinstallation assessment or through observations recorded during its installation. NOTE A tested barrier has the greatest level of assurance. EXAMPLE Observations that can be recorded during a cement displacement operation to support the evaluation of the cement as a barrier include a mud displacement volume equal to the calculated capacity of the casing string, and observed lift pressure matching the calculated lift pressure.
Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards