This International Standard addresses the issues concerning software aspects of dependability and gives guidance on achievement of dependability in software performance influenced by management disciplines, design processes and application environments. It establishes a generic framework on software dependability requirements, provides a software dependability process for system life cycle applications, presents assurance criteria and methodology for software dependability design and implementation and provides practical approaches for performance evaluation and measurement of dependability characteristics in software systems. This standard is applicable for guidance to software system developers and suppliers, system integrators, operators and maintainers and users of software systems who are concerned with practical approaches and application engineering to achieve dependability of software products and systems.