Specifies design principles for card based services which apply to any sector, including mass transport, telecommunications, parking, banking, logical and physical access control. Recommends operational procedures to be followed when a user interacts with a card operated device so as to enter, use or leave a system. Facilitates user interactions with card operated systems by standardizing key components of the user interface. All devices should be accessible to users, as well as those with special needs. To help user interaction with the system, promote efficient use and user confidence, enable people with different abilities/ comprehension levels to use systems and improve learnability through consistency.