This document discusses specifying critical systems. It notes that functional requirements should define error checking, recovery from failures, and protections against system failures. Non-functional requirements should specify the required reliability and availability of the system. The document also mentions that reliability specifications should consider the probability of hardware components failing and how long repairs take, as well as the likelihood of software components containing defects and how long it takes to fix them.

1. Critical Systems Specification
Nitin V Pujari B.E – CS - Software Engineering – Critical Systems Specification Slide 1

2. Functional and non-functional requirements
System functional requirements may be
generated to define error checking and recovery
facilities and features that provide protection
against system failures.
Non-functional requirements may be generated
to specify the required reliability and availability
of the system.
Nitin V Pujari B.E – CS - Software Engineering – Critical Systems Specification Slide 2