Reliability Systems, applications or services are deemed reliable if they comply with relevant requirements (e.g. quality of service requirements) and if they function in a way that does not differ to an unacceptable degree from users' expectations. In this context, the term ‘reliability’ is used as an umbrella term, including (at least) the following concepts: • availability (i.e. permanent usability) • robustness (i.e. functional stability) • safety (i.e. possibility to operate and apply such systems or products without being harmed or without harming the environment) • confidentiality (i.e. no unauthorized disclosure of information) • integrity (i.e. no unauthorized modification or destruction of data) • maintainability (i.e. possibility to maintain/ restore operation by repair works; possibility to upgrade the system) Page 20