/Header\r"<CR>
Note that the effect of a command might also be silenced, e.g., when the
mapping selects another entry for command line completion it won't be
displayed.
Prompts will still be given, e.g., for inputdialog().
Using "<silent>" for an abbreviation is possible, but will cause redrawing of
the command line to fail.

						*:map-<script>* *:map-script*
If the first argument to one of these commands is "<script>" and it is used to
define a new mapping or abbreviation, the mapping will only remap characters
in the {rhs} using mappings that were defined local to a script, starting with
"<SID>".  This can be used to avoid that mappings from outside a script
interfere (e.g., when CTRL-V is remapped in mswin.vim), but do use other
mappings defined in the script.
Note: ":map <script>" and ":noremap <script>" do the same thing.  The
"<script>" overrules the command name.  Using ":noremap <script>" is
preferred, because it's clearer that remapping is (mostly) disabled.

				*:map-<unique>* *:map-unique* *E226* *E227*
If the first argument to one of these commands is "<unique>" and it is used to
define a new mapping or abbreviation, the command will fail if the mapping or
abbreviation already exists.  Example: >
	:map <unique> ,w  /[#&!]<CR>
When defining a local mapping, there will also be a check if a global map
already exists which is equal.
Example of what will fail: >
	:map ,w  /[#&!]<CR>
	:map <buffer> <unique> ,w  /[.,;]<CR>
If you want to map a key and then have it do what it was originally mapped to,
have a look at |maparg()|.

						*:map-<expr>* *:map-expression*
If the first argument to one of these commands is "<expr>" and it is used to
define a new mapping or abbreviation, the argument is an expression.  The
expression is evaluated to obtain the {rhs} that is used.  Example: >
	:inoremap <expr> . <SID>InsertDot()
The result of the s:InsertDot() function will be inserted.  It could check the
text before the cursor and start omni completion when some condition is met.
Using a script-local function is preferred, to avoid polluting the global
namespace.  Use <SID> in the RHS so that the script that the mapping was
defined in can be found.

For abbreviations |v:char| is set to the character that was typed to trigger
the abbreviation.  You can use this to decide how to expand the {lhs}.  You
should not either insert or change the v:char.

In case you want the mapping to not do anything, you can have the expression
evaluate to an empty string.  If something changed that requires Vim to
go through the main loop (e.g. to update the display), return "\<Ignore>".
This is similar to "nothing" but makes Vim return from the loop that waits for
input.

Keep in mind that the expression may be evaluated when looking for
typeahead, before the previous command has been executed.  For example: >
	func StoreColumn()
	  let g:column = col('.')
	  return 'x'
	endfunc
	nnoremap <expr> x StoreColumn()
	nmap ! f!x
You will notice that g:column has the value from before executing "f!",
because "x" is evaluated before "f!" is executed.
This can be solved by inserting <Ignore> before the character that is
expression-mapped: >
	nmap ! f!<Ignore>x

Be very careful about side effects!  The expression is evaluated while
obtaining characters, you may very well make the command dysfunctional.
Therefore the following is blocked for <expr> mappings:
- Changing the buffer text |textlock|.
- Editing another buffer.
- The |:normal| command.
- Moving the cursor is allowed, but it is restored afterwards.
- If the cmdline is changed, the old text and cursor position are restored.
If you want the mapping to do any of these let the returned characters do
that, or use a |<Cmd>| mapping instead.

You can use getchar(), it consumes typeahead if there is any. E.g., if you
have these mappings: >
  inoremap <expr> <C-L> nr2char(getchar())
  inoremap <expr> <C-L>x "foo"
If you now type CTRL-L nothing happens yet, Vim needs the next character to
decide what mapping