Control panel metaphor. Typing effort is minimal User errors are trapped by the interface Context-dependent help can be provided. If there are many choices, some menu structuring facility must be used Experienced users find menus slower than command language Menu structuring Scrolling menus When a choice is not displayed, the menu can be scrolled to reveal more choices. The menus are organized in a hierarchy. Command interfaces User types commands to give instructions to the system e.g. UNIX May be implemented using cheap terminals.
Users have to learn and remember a command language.
Command interfaces are therefore unsuitable for occasional users Users make errors in command. The help and message system may be integrated Help and message system Error message design Error message design is critically important. The dynamic characteristics of the display can improve information presentation. People are not so good at reading screen as they are text. Help system use Multiple entry points should be provided so that the user can get into the help system from different places.