This International Standard provides a framework for assessment, verification and validation of all types of calculation methods used as tools for fire safety engineering. It does not address specific fire models, but is intended to be applicable to both analytical models and complex numerical models that are addressed as calculation methods in the context of this International Standard. It is not a step-by-step procedure, but does describe techniques for detecting errors and finding limitations in a calculation method. This International Standard includes - a process to ensure that the equations and calculation methods are implemented correctly (verification) and that the calculation method being considered is solving the appropriate problem (validation), - requirements for documentation to demonstrate the adequacy of the scientific and technical basis of a calculation method, - requirements for data against which a calculation method's predicted results shall be checked, - guidance on use of this International Standard by developers and/or users of calculation methods, and by those assessing the results obtained by using calculation methods.