4.1 Possible sources.
Problem reports.
Helpdesk and support team.
Trainers and consultants.
Customer suggestions and complaints.
Improvements made by users.
Unintended uses.
Comparable products.
Old designs and specifications.
Badly written contracts.
4.2 Getting requirement for mass-market products.
The vital role of the marketing department.
Turning market reports into requirements.
4.3 User requirements in subsystem projects.
Subsystems inherit requirements,
adding a few of their own.