
Architecture and Quality 375
Reliability requirement. N While in [state | mode] X, the system shall [provide service |
perform function] Y with a mean time between failure of at least Z [years | days | hours |
minutes | seconds | milliseconds] of continuous operation.
Condition = “While in [state | mode] X”
Quality criterion = “the system shall [provide service | perform function] Y”
reshold = “with a mean time between failure of at least Z [years | days | hours | minutes
| seconds | milliseconds] of continuous operation”
Safety requirement (accident prevention attributes). N While in [state | mode] X, the sys-
tem shall prevent ...