[option] is used to denote optional parts of a command. Many vi commands have an optional count. [cnt] means that an optional number may precede the command to multiply or iterate the command. {variable item} is used to denote parts of the command which must appear, but can take a number of different values. <character [-character]> means that the character or one of the characters in the range described between the two angle brackets is to be typed. For example <esc> means the escape key is to be typed. <a-z> means that a lower case letter is to be typed. ^<character> means that the character is to be typed as a control character, that is, with the <cntl> key held down while simultaneously typing the specified character. In this document control characters will be denoted using the upper case character, but ^<uppercase chr> and ^<lowercase chr> are equivalent. That is, for example, <^D> is equal to <^d>. The most common character abbreviations used in this list are as follows: