The key is always an alpha-numeric name that is case insensitive. If the value of an option does not contain whitespace, it may appear directly after the equals sign, otherwise, the value must be quoted. Values are composed of a sequence of text and, if allowed, variable substitutions. In the syntax diagrams, the possible values for various options are specified without quotes. However, quotes are always acceptable around an option value.
Many options have a more restricted set of possible values than represented by the above syntax.
See the individual options for details.