'x', 'y' or 'z'
	[a-zA-Z]$	any alphabetic character at the end of a line
	\c[a-z]$	same
	[А-яЁё]		Russian alphabet (with utf-8 and cp1251)

								*/[\n]*
	With "\_" prepended the collection also includes the end-of-line.
	The same can be done by including "\n" in the collection.  The
	end-of-line is also matched when the collection starts with "^"!  Thus
	"\_[^ab]" matches the end-of-line and any character but "a" and "b".
	This makes it Vi compatible: Without the "\_" or "\n" the collection
	does not match an end-of-line.
								*E769*
	When the ']' is not there Vim will not give an error message but
	assume no collection is used.  Useful to search for '['.  However, you
	do get E769 for internal searching.  And be aware that in a
	`:substitute` command the whole command becomes the pattern.  E.g.
	":s/[/x/" searches for "[/x" and replaces it with nothing.  It does
	not search for "[" and replaces it with "x"!

								*E944* *E945*
	If the sequence begins with "^", it matches any single character NOT
	in the collection: "[^xyz]" matches anything but 'x', 'y' and 'z'.
	- If two characters in the sequence are separated by '-', this is
	  shorthand for the full list of ASCII characters between them.  E.g.,
	  "[0-9]" matches any decimal digit.  If the starting character exceeds
	  the ending character, e.g. [c-a], E944 occurs.  Non-ASCII characters
	  can be used, but the character values must not be more than 256 apart
	  in the old regexp engine.  For example, searching by [\u3000-\u4000]
	  after setting re=1 emits a E945 error.  Prepending \%#=2 will fix it.
	- A character class expression is evaluated to the set of characters
	  belonging to that character class.  The following character classes
	  are supported:
		  Name	      Func	Contents ~
*[:alnum:]*	  [:alnum:]   isalnum	ASCII letters and digits
*[:alpha:]*	  [:alpha:]   isalpha	ASCII letters
*[:blank:]*	  [:blank:]		space and tab
*[:cntrl:]*	  [:cntrl:]   iscntrl	ASCII control characters
*[:digit:]*	  [:digit:]		decimal digits '0' to '9'
*[:graph:]*	  [:graph:]   isgraph	ASCII printable characters excluding
					space
*[:lower:]*	  [:lower:]   (1)	lowercase letters (all letters when
					'ignorecase' is used)
*[:print:]*	  [:print:]   (2)	printable characters including space
*[:punct:]*	  [:punct:]   ispunct	ASCII punctuation characters
*[:space:]*	  [:space:]		whitespace characters: space, tab, CR,
					NL, vertical tab, form feed
*[:upper:]*	  [:upper:]   (3)	uppercase letters (all letters when
					'ignorecase' is used)
*[:xdigit:]*	  [:xdigit:]		hexadecimal digits: 0-9, a-f, A-F
*[:return:]*	  [:return:]		the <CR> character
*[:tab:]*	  [:tab:]		the <Tab> character
*[:escape:]*	  [:escape:]		the <Esc> character
*[:backspace:]*	  [:backspace:]		the <BS> character
*[:ident:]*	  [:ident:]		identifier character (same as "\i")
*[:keyword:]*	  [:keyword:]		keyword character (same as "\k")
*[:fname:]*	  [:fname:]		file name character (same as "\f")
	  The square brackets in character class expressions are additional to
	  the square brackets delimiting a collection.  For example, the
	  following is a plausible pattern for a UNIX filename:
	  "[-./[:alnum:]_~]\+".  That is, a list of at least one character,
	  each of which is either '-', '.', '/', alphabetic, numeric, '_' or
	  '~'.
	  These items only work for 8-bit characters, except [:lower:] and
	  [:upper:] also work for multibyte characters when using the new
	  regexp engine.  See |two-engines|.  In the future these items may
	  work for multibyte characters.  For now, to get all "alpha"
	  characters you can use: [[:lower:][:upper:]].

	  The "Func" column shows what library function is used.  The
	  implementation depends on the system.  Otherwise:
	  (1) Uses islower() for ASCII and Vim builtin rules for other
	  characters.
	  (2) Uses Vim builtin rules
	  (3) As with (1) but using isupper()
							*/[[=* *[==]*
	- An equivalence class.  This means that characters are matched that
	  have almost the same