editors usually have to reserve all keys with letters and symbols for the printing of characters, any special commands for actions other than adding text to the buffer must be assigned to keys that do not produce characters, such as function keys, or combinations of modifier keys such as , and with regular keys. Vi has the property that most ordinary keys are connected to some kind of command for positioning, altering text, searching and so forth, either singly or in key combinations. Many commands can be touch typed without the use of or . Other types of editors generally require the user to move their hands from the home row when touch typing: To use a mouse to select text, commands, or menu items in a GUI editor. To the arrow keys or editing functions (Home / End or Function Keys). To invoke commands using modifier keys in conjunction with the standard typewriter keys. For instance, in vi, replacing a word is replacement text, which is a combination of two independent commands (change and word-motion) together with a transition into and out of insert mode. Text between the cursor position and the end of the word is overwritten by the replacement text. The operation can be repeated at some other location by typing , the effect being that the word starting at that location will be replaced with the same replacement text. A human–computer interaction textbook notes on its first page that "One of the classic UI foibles—told and re-told by HCI educators around the world—is the vi editor's lack of feedback when switching between modes. Many a user made the mistake of providing input while in command mode or entering a command while in input mode." Contemporary derivatives and clones Vim "Vi IMproved" has many additional features compared to vi, including (scriptable) syntax highlighting, mouse support, graphical versions, visual mode, many new editing commands and a large amount of extension in the area of ex commands. Vim is included with almost every Linux distribution (and is also shipped with every copy of Apple macOS). Vim also has a vi compatibility mode, in which Vim is more compatible with vi than it would be otherwise, although some vi features, such as open mode, are missing in Vim, even in compatibility mode. This mode is controlled by the option. It is automatically turned on by Vim when it is started