A device is provided having a touchscreen, a storage device and a processor connected to the touchscreen and the storage device. The touchscreen is arranged to display a keyboard defined by a keyboard layout and to receive an input on the keyboard. The storage device is arranged to store a specification for a restricted language, and the specification includes a grammar and vocabulary for the restricted language and includes annotations defining additional keyboard components in relation to specific elements within the grammar. The processor is arranged to define the keyboard layout, determine a specific element within the grammar referred to by a received input, and redefine the keyboard layout to include the additional keyboard components defined in the annotation for the determined specific element within the grammar.