ntirely removed, its absence may itself convey information about the status. The most obvious example of this is where a message is displayed that the system is "busy" or "waiting". For a sighted user, when this text disappears, it is normally an indication that the state is now available. However non-sighted users would be unaware of this change, unless the end of the waiting state results in a change of context for the user. Where updating the visible message (e.g., to "system available") is not feasible,