register
			{reg-name}.  {reg-name} must be a single letter, and
			must be the name of a writable register (see
			|registers|).  "@@" can be used for the unnamed
			register, "@/" for the search pattern.
			If the result of {expr1} ends in a <CR> or <NL>, the
			register will be linewise, otherwise it will be set to
			charwise.
			This can be used to clear the last search pattern: >
				:let @/ = ""
<			This is different from searching for an empty string,
			that would match everywhere.

:let @{reg-name} .= {expr1}
			Append {expr1} to register {reg-name}.  If the
			register was empty it's like setting it to {expr1}.

:let &{option-name} = {expr1}			*:let-option* *:let-&*
			Set option {option-name} to the result of the
			expression {expr1}.  A String or Number value is
			always converted to the type of the option.
			For an option local to a window or buffer the effect
			is just like using the |:set| command: both the local
			value and the global value are changed.
			Example: >
				:let &path = &path .. ',/usr/local/include'

:let &{option-name} .= {expr1}
			For a string option: Append {expr1} to the value.
			Does not insert a comma like |:set+=|.

:let &{option-name} += {expr1}
:let &{option-name} -= {expr1}
			For a number or boolean option: Add or subtract
			{expr1}.

:let &l:{option-name} = {expr1}
:let &l:{option-name} .= {expr1}
:let &l:{option-name} += {expr1}
:let &l:{option-name} -= {expr1}
			Like above, but only set the local value of an option
			(if there is one).  Works like |:setlocal|.

:let &g:{option-name} = {expr1}
:let &g:{option-name} .= {expr1}
:let &g:{option-name} += {expr1}
:let &g:{option-name} -= {expr1}
			Like above, but only set the global value of an option
			(if there is one).  Works like |:setglobal|.

:let [{name1}, {name2}, ...] = {expr1}		*:let-unpack* *E687* *E688*
			{expr1} must evaluate to a |List|.  The first item in
			the list is assigned to {name1}, the second item to
			{name2}, etc.
			The number of names must match the number of items in
			the |List|.
			Each name can be one of the items of the ":let"
			command as mentioned above.
			Example: >
				:let [s, item] = GetItem(s)
<			Detail: {expr1} is evaluated first, then the
			assignments are done in sequence.  This matters if
			{name2} depends on {name1}.  Example: >
				:let x = [0, 1]
				:let i = 0
				:let [i, x[i]] = [1, 2]
				:echo x
<			The result is [0, 2].

:let [{name1}, {name2}, ...] .= {expr1}
:let [{name1}, {name2}, ...] += {expr1}
:let [{name1}, {name2}, ...] -= {expr1}
			Like above, but append/add/subtract the value for each
			|List| item.

:let [{name}, ..., ; {lastname}] = {expr1}				*E452*
			Like |:let-unpack| above, but the |List| may have more
			items than there are names.  A list of the remaining
			items is assigned to {lastname}.  If there are no
			remaining items {lastname} is set to an empty list.
			Example: >
				:let [a, b; rest] = ["aval", "bval", 3, 4]
<
:let [{name}, ..., ; {lastname}] .= {expr1}
:let [{name}, ..., ; {lastname}] += {expr1}
:let [{name}, ..., ; {lastname}] -= {expr1}
			Like above, but append/add/subtract the value for each
			|List| item.

						*:let=<<* *:let-heredoc*
					*E990* *E991* *E172* *E221* *E1145*
:let {var-name} =<< [trim] [eval] {endmarker}
text...
text...
{endmarker}
			Set internal variable {var-name} to a |List|
			containing the lines of text bounded by the string
			{endmarker}.

			If "eval" is not specified, then each line of text is
			used as a |literal-string|, except that single quotes
			does not need to be doubled.
			If "eval" is specified, then any Vim expression in the
			form {expr} is evaluated and the result replaces the
			expression, like with |interpolated-string|.
			Example where $HOME is expanded: >
				let lines =<< trim eval END
				  some text
				  See the file {$HOME}/.vimrc
				  more text
				END
<			There can be multiple Vim expressions in a single line
			but an expression cannot span multiple lines.  If any