A system for generating, on a user terminal, a user interface having at least two interface items, where the system is configured to store at least two sets of data each corresponding to the interface items. A first set of data includes data for generating and controlling the performance of an operation associated with a first of interface items, and a second said set of data includes data for generating and controlling the performance of an operation associated with a second of the interface items. When a user interacts with the first interface item, the system is configured to perform the action associated with the first interface item, independent of the second interface item and without performing any other action corresponding to the user interface.