Business analysis - Record
Functional specification
A detailed description of how a system is expected to behave
What's it for?
Describes expected system behaviour in enough detail for people to build and test it consistently.
For example…
The spec defines how discounts stack, who can override them, and what error appears when stock is insufficient
A functional specification explains exactly what happens when an invoice is rejected, including status changes, notifications and allowed next actions
Think of it like…
Detailed recipe with temperatures and timings—not just 'make a cake'