Ticket issing system for rail travel: Omissions, ambiguities, problems
Requirements aren't always complete no matter who specs them out. As an exercise, take a look at the following description of a ticket issuing system for rail travel.
The ticket issuing system is intended to automate the sale of rail tickets. Users will be able to select their destination, and input a credit card and a personal identification number. The rail ticket is then issued and their credit card account charged with its cost. When the user presses the start button, a menu display of potential destinations is activated along with a message to the user to select a destination. Once a destination has been selected, users are requested to input their credit card. Its validity is checked and the user is then requested to input a personal identification number. When the credit transaction has been validated, the ticket is issued.
In order to proceed with developing this system, it's necessary to analyze the above description. There are a number of ambiguities and omissions in the above description.
Find one of more omissions/ambiguities and describe what is problematic with each and how you would improve the description.