Thus their meaning according to the context changes and their labels are refreshed on the screen. Soft Keys are problematic for visually handicapped users using speech adaptation, as they can not rely on a stable layout of the keys and would therefore easily perform wrong operations. Nevertheless, all these components are quite traditional and non visual equivalents have been developed for the need of the visually handicapped users, in the context of MS-DOS or Windows, based on speech, Braille or magnified presentation of data. The presentation of data on a Braille display, or using a speech synthesiser, or magnifying the data on the screen, has to put the components in a sequence. The order of the components in the sequence will be chosen according to the context of the application and can be different for users who do not have the global view of the screen.
Some extra guidance has to be provided to compensate the absence of a global view of the screen.
This guidance can be given using textual comments just before an Interaction Component or just after. Non verbal feedback Non verbal feedback is extremely useful in non visual interfaces in order to convey feedback rapidly. Using beeps is a simple and low cost method to achieve this. This is particularly useful to solve the Soft Key problem. Pressing a Soft Key once gives information on the associated command while pressing it twice would activates the command.