The CLI supports both command abbreviation and command completion. If the keystrokes entered are enough to match a valid command, the CLI displays the remainder of the command syntax when the Tab key or space bar is pressed. When typing a command, the Tab key or space bar invokes auto-completion. If the keystrokes entered are definite, auto-completion will complete the command. If the letters are not sufficient to identify a specific command, pressing the Tab key or space bar will display commands matching the letters entered. System commands are available in all CLI context levels.