(sec_sys_handbook)= # Part 6 - System This part provides an overview of existing methods for system applications, followed by the consideration of specific aspects relevant to space applications, including: * Reliability assessment of phased missions, * The use of importance measures for system optimization, * Assessment of degraded system modes, * Modelling of common cause failures and system level considerations for {term}`degradation failures `. A dedicated section, on non-part related {term}`systematic failures ` includes a satellite level anomaly occurrence model derived from in-orbit return, as well as a specific discussion on the consideration of software-related failures, in the context of reliability prediction for space applications. This part contains the following sections: ```{tableofcontents} ```