A special situation exists when a system and its software are both being deÞned concurrently. Then the functionality,
interfaces, performance, and other attributes and constraints of the software are not predeÞned, but
rather are jointly deÞned and subject to negotiation and change. This makes it more difÞcult, but no less
important, to meet the characteristics stated in 4.3. In particular, an SRS that does not comply with the
requirements of its parent system speciÞcation is incorrect.