We will implement a web panel with a grid with attributes and variables, and see the system’s Start, Refresh and Load events, as well as user events, particularly the Click associated with an attribute or variable in the grid. We will call the Attraction transaction modified by the pattern, in Update mode. We will see the system’s &Mode variable in transactions, and the values it takes. We will see that the attributes correspond to the output and the variables to the input. We will see how to make a variable Readonly.