window.  Possible values:
	|fold-manual|	manual	    Folds are created manually.
	|fold-indent|	indent	    Lines with equal indent form a fold.
	|fold-expr|	expr	    'foldexpr' gives the fold level of a line.
	|fold-marker|	marker	    Markers are used to specify folds.
	|fold-syntax|	syntax	    Syntax highlighting items specify folds.
	|fold-diff|	diff	    Fold text that is not changed.

						*'foldminlines'* *'fml'*
'foldminlines' 'fml'	number	(default 1)
			local to window
	Sets the number of screen lines above which a fold can be displayed
	closed.  Also for manually closed folds.  With the default value of
	one a fold can only be closed if it takes up two or more screen lines.
	Set to zero to be able to close folds of just one screen line.
	Note that this only has an effect on what is displayed.  After using
	"zc" to close a fold, which is displayed open because it's smaller
	than 'foldminlines', a following "zc" may close a containing fold.

						*'foldnestmax'* *'fdn'*
'foldnestmax' 'fdn'	number	(default 20)
			local to window
	Sets the maximum nesting of folds for the "indent" and "syntax"
	methods.  This avoids that too many folds will be created.  Using more
	than 20 doesn't work, because the internal limit is 20.

						*'foldopen'* *'fdo'*
'foldopen' 'fdo'	string	(default "block,hor,mark,percent,quickfix,search,tag,undo")
			global
	Specifies for which type of commands folds will be opened, if the
	command moves the cursor into a closed fold.  It is a comma-separated
	list of items.
	NOTE: When the command is part of a mapping this option is not used.
	Add the |zv| command to the mapping to get the same effect.
	(rationale: the mapping may want to control opening folds itself)

		item		commands ~
		all		any
		block		(, {, [[, [{, etc.
		hor		horizontal movements: "l", "w", "fx", etc.
		insert		any command in Insert mode
		jump		far jumps: "G", "gg", etc.
		mark		jumping to a mark: "'m", CTRL-O, etc.
		percent		"%"
		quickfix	":cn", ":crew", ":make", etc.
		search		search for a pattern: "/", "n", "*", "gd", etc.
				(not for a search pattern in a ":" command)
				Also for |[s| and |]s|.
		tag		jumping to a tag: ":ta", CTRL-T, etc.
		undo		undo or redo: "u" and CTRL-R
	When a movement command is used for an operator (e.g., "dl" or "y%")
	this option is not used.  This means the operator will include the
	whole closed fold.
	Note that vertical movements are not here, because it would make it
	very difficult to move onto a closed fold.
	In insert mode the folds containing the cursor will always be open
	when text is inserted.
	To close folds you can re-apply 'foldlevel' with the |zx| command or
	set the 'foldclose' option to "all".

						*'foldtext'* *'fdt'*
'foldtext' 'fdt'	string	(default "foldtext()")
			local to window
	An expression which is used to specify the text displayed for a closed
	fold.  The context is set to the script where 'foldexpr' was set,
	script-local items can be accessed.  See |fold-foldtext| for the
	usage.

	The expression will be evaluated in the |sandbox| if set from a
	modeline, see |sandbox-option|.
	This option cannot be set in a modeline when 'modelineexpr' is off.

	It is not allowed to change text or jump to another window while
	evaluating 'foldtext' |textlock|.

	When set to an empty string, foldtext is disabled, and the line
	is displayed normally with highlighting and no line wrapping.

						*'formatexpr'* *'fex'*
'formatexpr' 'fex'	string	(default "")
			local to buffer
	Expression which is evaluated to format a range of lines for the |gq|
	operator or automatic formatting (see 'formatoptions').  When this
	option is empty 'formatprg' is used.

	The |v:lnum|  variable holds the first line to be formatted.
	The |v:count| variable holds the number of lines to be formatted.
	The |v:char|  variable holds the character that is going to be
		      inserted if the expression is being evaluated due to
		      automatic formatting.  This can be empty.  Don't insert
		      it yet!

	Example: