ECSS-E-40 PART 1B, SPACE ENGINEERING SOFTWARE - PART 1: PRINCIPLES AND REQUIREMENTS (23 NOV 2003)., This software engineering Standard concerns the “product software”, i.e. software that is part of a space system product tree and developed as part of a space project. This Standard is applicable, to the extent defined by the tailoring process, to all the elements of a space system, including the space segment, the launch service segment and the ground segment. This Standard covers all aspects of space software engineering including requirements definition, design, production, verification and validation, transfer, operations and maintenance.