Begin with a responsibility the team needs to fulfil: reviewing requests, coordinating internal work, maintaining records or preparing an agreed report. Follow an ordinary case from the first entry to the person who uses the result. That discussion establishes the information, decisions and exceptions the application must support. A screen list becomes useful after those responsibilities are understood.
The service can cover a new application or an improvement to an existing arrangement. We compare an appropriate product configuration, a supported connection and a custom build before choosing the route. A first release can be bounded without leaving its main task unfinished. The scope names what users can complete, what remains a human decision and how the team will operate the result.