And it is processed not by Vim itself, but by the terminal emulator that sends Esc character to Vim. So the shortcut Ctrl+[ was not invented by vi author, but i

And it is processed not by Vim itself, but by the terminal emulator that sends Esc character to Vim. So the shortcut Ctrl+[ was not invented by vi author, but is a consequence of using Esc to exit from the edit mode.