('wrapscan' is ignored)
	w	scan buffers from other windows
	b	scan other loaded buffers that are in the buffer list
	u	scan the unloaded buffers that are in the buffer list
	U	scan the buffers that are not in the buffer list
	k	scan the files given with the 'dictionary' option
	kspell  use the currently active spell checking |spell|
	k{dict}	scan the file {dict}.  Several "k" flags can be given,
		patterns are valid too.  For example: >vim
			set cpt=k/usr/dict/*,k~/spanish
<	s	scan the files given with the 'thesaurus' option
	s{tsr}	scan the file {tsr}.  Several "s" flags can be given, patterns
		are valid too.
	i	scan current and included files
	d	scan current and included files for defined name or macro
		|i_CTRL-X_CTRL-D|
	]	tag completion
	t	same as "]"
	f	scan the buffer names (as opposed to buffer contents)
	F{func}	call the function {func}.  Multiple "F" flags may be specified.
		Refer to |complete-functions| for details on how the function
		is invoked and what it should return.  The value can be the
		name of a function or a |Funcref|.  For |Funcref| values,
		spaces must be escaped with a backslash ('\'), and commas with
		double backslashes ('\\') (see |option-backslash|).
		If the Dict returned by the {func} includes {"refresh": "always"},
		the function will be invoked again whenever the leading text
		changes.
		Completion matches are always inserted at the keyword
		boundary, regardless of the column returned by {func} when
		a:findstart is 1.  This ensures compatibility with other
		completion sources.
		To make further modifications to the inserted text, {func}
		can make use of |CompleteDonePre|.
		If generating matches is potentially slow, |complete_check()|
		should be used to avoid blocking and preserve editor
		responsiveness.
	F	equivalent to using "F{func}", where the function is taken from
		the 'completefunc' option.
	o	equivalent to using "F{func}", where the function is taken from
		the 'omnifunc' option.

	Unloaded buffers are not loaded, thus their autocmds |:autocmd| are
	not executed, this may lead to unexpected completions from some files
	(gzipped files for example).  Unloaded buffers are not scanned for
	whole-line completion.

	As you can see, CTRL-N and CTRL-P can be used to do any 'iskeyword'-
	based expansion (e.g., dictionary |i_CTRL-X_CTRL-K|, included patterns
	|i_CTRL-X_CTRL-I|, tags |i_CTRL-X_CTRL-]| and normal expansions).

	An optional match limit can be specified for a completion source by
	appending a caret ("^") followed by a {count} to the source flag.
	For example: ".^9,w,u,t^5" limits matches from the current buffer
	to 9 and from tags to 5.  Other sources remain unlimited.
	Note: The match limit takes effect only during forward completion
	(CTRL-N) and is ignored during backward completion (CTRL-P).

						*'completefunc'* *'cfu'*
'completefunc' 'cfu'	string	(default "")
			local to buffer
	This option specifies a function to be used for Insert mode completion
	with CTRL-X CTRL-U. |i_CTRL-X_CTRL-U|
	See |complete-functions| for an explanation of how the function is
	invoked and what it should return.  The value can be the name of a
	function, a |lambda| or a |Funcref|. See |option-value-function| for
	more information.
	This option cannot be set from a |modeline| or in the |sandbox|, for
	security reasons.

					*'completefuzzycollect'* *'cfc'*
'completefuzzycollect' 'cfc'	string	(default "")
			global
	A comma-separated list of strings to enable fuzzy collection for
	specific |ins-completion| modes, affecting how matches are gathered
	during completion.  For specified modes, fuzzy matching is used to
	find completion candidates instead of the standard prefix-based
	matching.  This option can contain the following values:

	keyword		keywords in the current file	|i_CTRL-X_CTRL-N|
			keywords with flags ".", "w",	|i_CTRL-N| |i_CTRL-P|
			"b", "u", "U" and "k{dict}" in 'complete'
			keywords in 'dictionary'	|i_CTRL-X_CTRL-K|

	files		file names			|i_CTRL-X_CTRL-F|

	whole_line