The Presentation Controller can work in two modes: using menus and dialogue windows (menu mode), or using command line mode (command mode).
In command mode the commands/values are automatically validated during introduction. The selection of an option is done by writing its name, a value being assigned to an argument by writing the name of the variable and the value.
In menu mode only valid commands and arguments are available for selection/value assignment.
At the semantic level the Presentation Controller has the task of validating the values by checking the related data types invariants.