This term is defined in ECSS-E-ST-40C as
process to confirm that adequate specifications and inputs exist for any activity, and that the outputs of the activities are correct and consistent with the specifications and input

This term is defined in ECSS-S-ST-00-01C as
process which demonstrates through the provision of objective evidence that the product is designed and produced according to its specifications and the agreed deviations and waivers, and is free of defects