Keywords are used in searching and recognizing with many commands: "w", "", "[i", etc. It is also used for "\k" in a |pattern|. See 'isfname' for a description of the format of this option. For '@' characters above 255 check the "word" character class (any character that is not white space or punctuation). For C programs you could use "a-z,A-Z,48-57,_,.,-,>". For a help file it is set to all non-blank printable characters except '', '"' and '|' (so that CTRL-] on a command finds the help for that command). When the 'lisp' option is on the '-' character is always included. This option also influences syntax highlighting, unless the syntax uses |:syn-iskeyword|. NOTE: This option is set to the Vi default value when 'compatible' is set and to the Vim default value when 'compatible' is reset.