2.2.1-1 Layered Command Language

A command language should be designed so that its functions are organized in groups (or "layers") for ease in learning and use.

Additional Information:
A user should be able to display the next of a set of received messages with some simple command such as READ NEXT, although a complete command to retrieve any message might include potential specification of which message, from which message list, in which format, to which output device. The fundamental layer of the language should be the easiest, allowing use of the system by people with little training and/or limited needs. Successive layers of the command language can then increase in complexity for users with greater skills. In effect, simple versions of commands can be recognized by defaulting all of the optional parameters. Control forms might be used to display default options for complicated commands.