Commands consist of single letters. On some computers they may be realized as special function keys or as choices from a menu. Commands are not echoed on the screen, and are obeyed immediately, without waiting for a <RET> key to be pressed. This contributes to the interactive feeling of the Elan Programming Environment.
To an unknown or unacceptable command the Elan Programming Environment reacts by showing for about one second a menu of all acceptable commands (we use the negative menu technique: a menu is displayed only when an unacceptable command is given). In all moods except edit-mood and execute-mood the letter h (help-command) can be used to provoke such a menu.