What is the difference between primary and secondary users? The text gives an example of a ticket agent being a primary user of a reservation system and the ticket buyer being the secondary user. Name four examples of systems that have primary and secondary users.

What will be an ideal response?

Here are a few:
System Primary user Secondary user
Cash registers Clerk Shopper Library checkout Librarian Patron Directory Assistance Operator Caller Stock trading Stock broker Stock owner Hospital admission Admissions staff Patient Insurance companies Insurance agent Insured UPS delivery system UPS staff Recipients NASA Mission Control Mission control staff Astronauts Air traffic control Air traffic controllers Pilots, passengers