diff --git a/doc/vital/Data/String.txt b/doc/vital/Data/String.txt
index d3b3bd31b..d411067b9 100644
--- a/doc/vital/Data/String.txt
+++ b/doc/vital/Data/String.txt
@@ -139,6 +139,10 @@ dstring({expr})				*Vital.Data.String.dstring()*
 lines({str})				*Vital.Data.String.lines()*
 	Splits into list of strings of each lines of {str}.
 
+strchars({str})				*Vital.Data.String.strchars()*
+	Returns the number of characters in String {str}.
+	This is a polyfill of |strchars()| when it was not provided.
+
 contains_multibyte({str})	*Vital.Data.String.contains_multibyte()*
 	Return Number 1 if String {str} contains a multi-byte character,
 	otherwise zero.
diff --git a/doc/vital/Mapping.txt b/doc/vital/Mapping.txt
index d451350f3..dcc6d780c 100644
--- a/doc/vital/Mapping.txt
+++ b/doc/vital/Mapping.txt
@@ -1,4 +1,4 @@
-*vital/Mapping.txt*		Utilities for mapping.
+*vital/Mapping.txt*		Utilities for mapping / abbreviation.
 
 Maintainer: tyru    <tyru.exe@gmail.com>
 
@@ -12,14 +12,129 @@ INTERFACE			|Vital.Mapping-interface|
 ==============================================================================
 INTRODUCTION				*Vital.Mapping-introduction*
 
-*Vital.Mapping* is TODO
+*Vital.Mapping* is a utility functions related to |:map|, |:unmap|,
+|:abbreviate|, |:unabbreviate| commands.
 
 ==============================================================================
 INTERFACE				*Vital.Mapping-interface*
 ------------------------------------------------------------------------------
 FUNCTIONS				*Vital.Mapping-functions*
 
-TODO
+				*Vital.Mapping.execute_abbr_command()*
+execute_abbr_command({mode}, {dict}, {lhs}, {rhs})
+	Execute `get_abbr_command(mode, dict, lhs, rhs)` result.
+	See |Mapping.get_abbr_command()|.
+
+				*Vital.Mapping.execute_map_command()*
+execute_map_command({mode}, {dict}, {lhs}, {rhs})
+	Execute `get_map_command(mode, dict, lhs, rhs)` result.
+	See |Mapping.get_map_command()|.
+
+				*Vital.Mapping.execute_unmap_command()*
+execute_unmap_command({mode}, {dict}, {lhs})
+	Execute `get_unmap_command(mode, dict, lhs)` result.
+	See |Mapping.get_unmap_command()|.
+
+				*Vital.Mapping.get_all_modes()*
+get_all_modes()
+	Returns string which represents all mode characters ("noiclxs").
+	NOTE: "v" is not contained. Because "x" and "s" already mean "v".
+
+				*Vital.Mapping.get_all_modes_list()*
+get_all_modes_list()
+	Returns |List| which represents all mode characters.
+	Same as `split(get_all_modes(), '\zs')` .
+	See |Mapping.get_all_modes()|.
+
+				*Vital.Mapping.get_abbr_command()*
+get_abbr_command({mode}, {dict}, {lhs}, {rhs})
+	Constructs |:abbreviate| command string.
+	{mode} is a character of mode.
+	{dict} is a |Dictionary| of options.
+	{lhs} and {rhs} are strings of lhs/rhs of |:map| command.
+	The options can be created by |Mapping.options_chars2dict()| or
+	|maparg()|'s return value when {dict} is non-zero.
+
+				*Vital.Mapping.get_map_command()*
+get_map_command({mode}, {dict}, {lhs}, {rhs})
+	Constructs |:map| command string.
+	{mode} is a character of mode.
+	{dict} is a |Dictionary| of options.
+	{lhs} and {rhs} are strings of lhs/rhs of |:map| command.
+	The options can be created by |Mapping.options_chars2dict()| or
+	|maparg()|'s return value when {dict} is non-zero.
+
+				*Vital.Mapping.get_unabbr_command()*
+get_unabbr_command({mode}, {dict}, {lhs})
+	Constructs |:unabbreviate| command string.
+	{mode} is a character of mode.
+	{dict} is a |Dictionary| of options.
+	{lhs} is a string of lhs of |:map| command.
+	The options can be created by |Mapping.options_chars2dict()| or
+	|maparg()|'s return value when {dict} is non-zero.
+
+				*Vital.Mapping.get_unmap_command()*
+get_unmap_command({mode}, {dict}, {lhs})
+	Constructs |:unabbreviate| command string.
+	{mode} is a character of mode.
+	{dict} is a |Dictionary| of options.
+	{lhs} is a string of lhs of |:map| command.
+	The options can be created by |Mapping.options_chars2dict()| or
+	|maparg()|'s return value when {dict} is non-zero.
+
+				*Vital.Mapping.options_chars2dict()*
+options_chars2dict({chars})
+	{chars} is a string which represents characters of options.
+	The return value is a |Dictionary| which is same as |maparg()|'s
+	return value when {dict} is non-zero.
+
+	chars	key ~
+	"e"	expr
+	"b"	buffer
+	"s"	silent
+	"S"	script
+	"u"	unique
+	"r"	noremap (inverse)
+	"n"	nowait
+
+	Example: >
+	options_chars2dict("bs") = {
+	  "expr": 0,
+	  "buffer": 1,
+	  "silent": 1,
+	  "script": 0,
+	  "unique": 0,
+	  "noremap": 1,
+	  "nowait": 0,
+	}
+<
+				*Vital.Mapping.options_chars2raw()*
+options_chars2raw({chars})
+	Same as `options_dict2raw(options_chars2dict(chars))` .
+	See |Mapping.options_dict2raw()| and |Mapping.options_chars2dict()|.
+
+	Example: >
+	options_dict2chars('eb') = '<expr><buffer>'
+<
+				*Vital.Mapping.options_dict2chars()*
+options_dict2chars({dict})
+	Converts {dict} to characters of options.
+
+	Example: >
+	options_dict2chars({'expr': 1, 'buffer': 1}) = 'eb'
+<
+				*Vital.Mapping.options_dict2raw()*
+options_dict2raw({dict})
+	{dict} is a |Dictionary| which represents options.
+	See |Mapping.options_chars2dict()| for the options.
+
+	Example: >
+	options_dict2raw({'expr': 1, 'buffer': 1}) = '<expr><buffer>'
+<
+				*Vital.Mapping.is_mode_char()*
+is_mode_char({char})
+	Returns non-zero if {char} is a character one of
+	"v", "n", "o", "i", "c", "l", "x", "s".
 
 ==============================================================================
 vim:tw=78:fo=tcq2mM:ts=8:ft=help:norl
diff --git a/doc/vital/Web/URI.txt b/doc/vital/Web/URI.txt
index 538693a5f..7b018c4f9 100644
--- a/doc/vital/Web/URI.txt
+++ b/doc/vital/Web/URI.txt
@@ -68,7 +68,11 @@ like_uri({str})				*Vital.Web.URI.like_uri()*
 
 					*Vital.Web.URI.new_default_pattern_set()*
 new_default_pattern_set()
-	Returns |Vital.Web.URI-PatternSet|.
+	Creates a new |Vital.Web.URI-PatternSet| object.
+
+					*Vital.Web.URI.clone_pattern_set()*
+clone_pattern_set({patternset})
+	Clones a |Vital.Web.URI-PatternSet| object.
 
 encode({str} [, {char-enc}])		*Vital.Web.URI.encode()*
 	Encodes {str} to Percent-encoding string.
@@ -144,70 +148,70 @@ is_path({str})
 is_query({str})
 is_fragment({str})
 
-    Returns non-zero value if {str} has right syntax
-    for each component. Returns zero otherwise.
+	Returns non-zero value if {str} has right syntax
+	for each component. Returns zero otherwise.
 
 *Vital.Web.URI-URI.clone()*
 clone()
 
-    This method clones a URI object itself. >
-    let s:URI = vital#{plugin-name}#new().import('Web.URI')
-    let uri = s:URI.new('http://example.com/')
-    let copyuri = uri.clone().relative('/a/b/c')
-    echo uri.to_string()
-    " => 'http://example.com/'
-    echo copyuri.to_string()
-    " => 'http://example.com/a/b/c'
+	This method clones a URI object itself. >
+	let s:URI = vital#{plugin-name}#new().import('Web.URI')
+	let uri = s:URI.new('http://example.com/')
+	let copyuri = uri.clone().relative('/a/b/c')
+	echo uri.to_string()
+	" => 'http://example.com/'
+	echo copyuri.to_string()
+	" => 'http://example.com/a/b/c'
 <
 *Vital.Web.URI-URI.relative()*
 relative({reluri})
 
-    This method ...
-    * Calculates a URI from
-    base URI and relative URI({reluri}).
-    * Changes the URI object itself (destructive).
-    * Returns the URI object itself.
-    * Calls |Vital.Web.URI-URI.relative()| implicitly.
-
-    Example: >
-    let s:URI = vital#{plugin-name}#new().import('Web.URI')
-    let BASE_URI = 'http://example.com/foo/bar'
-    let RELATIVE_URI = '../baz'
-    echo s:URI.new(BASE_URI).relative(RELATIVE_URI).to_string()
-    " => 'http://example.com/baz'
-
-    let BASE_URI = 'http://example.com/foo/bar/'
-    let RELATIVE_URI = '../baz'
-    echo s:URI.new(BASE_URI).relative(RELATIVE_URI).to_string()
-    " => 'http://example.com/foo/baz'
+	This method ...
+	* Calculates a URI from
+	base URI and relative URI({reluri}).
+	* Changes the URI object itself (destructive).
+	* Returns the URI object itself.
+	* Calls |Vital.Web.URI-URI.relative()| implicitly.
+
+	Example: >
+	let s:URI = vital#{plugin-name}#new().import('Web.URI')
+	let BASE_URI = 'http://example.com/foo/bar'
+	let RELATIVE_URI = '../baz'
+	echo s:URI.new(BASE_URI).relative(RELATIVE_URI).to_string()
+	" => 'http://example.com/baz'
+
+	let BASE_URI = 'http://example.com/foo/bar/'
+	let RELATIVE_URI = '../baz'
+	echo s:URI.new(BASE_URI).relative(RELATIVE_URI).to_string()
+	" => 'http://example.com/foo/baz'
 <
 *Vital.Web.URI-URI.canonicalize()*
 canonicalize()
 
-    This method ...
-    * Canonicalizes the URI.
-    * Changes the URI object itself (destructive).
-    * Returns the URI object itself.
-
-    See Web.URI.* modules for supported schemes.
-    For example, the following four URIs
-    becomes equivalent URI (http://example.com/).
-    * http://example.com
-    * http://example.com/
-    * http://example.com:/
-    * http://example.com:80/
-
-    Example: >
-    let s:URI = vital#{plugin-name}#new().import('Web.URI')
-    echo s:URI.new('http://example.com:80/').to_string()
-    " => 'http://example.com/'
+	This method ...
+	* Canonicalizes the URI.
+	* Changes the URI object itself (destructive).
+	* Returns the URI object itself.
+
+	See Web.URI.* modules for supported schemes.
+	For example, the following four URIs
+	becomes equivalent URI (http://example.com/).
+	* http://example.com
+	* http://example.com/
+	* http://example.com:/
+	* http://example.com:80/
+
+	Example: >
+	let s:URI = vital#{plugin-name}#new().import('Web.URI')
+	echo s:URI.new('http://example.com:80/').to_string()
+	" => 'http://example.com/'
 <
 *Vital.Web.URI-URI.default_port()*
 default_port()
 
-    This method returns the default port for current scheme.
-    (e.g.: 80 for "http" scheme)
-    See Web.URI.* modules for supported schemes.
+	This method returns the default port for current scheme.
+	(e.g.: 80 for "http" scheme)
+	See Web.URI.* modules for supported schemes.
 
 ------------------------------------------------------------------------------
 PATTERNSET OBJECT				*Vital.Web.URI-PatternSet*
@@ -232,28 +236,28 @@ According to RFC3986, URI allows
 but these characters often appears in ordinary text.
 This code lets the parser ignore these characters. >
 
-    let s:LoosePatternSet = s:URI.new_default_pattern_set()
+	let s:LoosePatternSet = s:URI.new_default_pattern_set()
 
-    " Remove "'", "(", ")" from default sub_delims().
-    function! s:LoosePatternSet.sub_delims() abort
-        return '[!$&*+,;=]'
-    endfunction
+	" Remove "'", "(", ")" from default sub_delims().
+	function! s:LoosePatternSet.sub_delims() abort
+	    return '[!$&*+,;=]'
+	endfunction
 
-    " Ignore trailing string after URI.
-    let NONE = []
-    let ret = URI.new_from_seq_string(
-    \               'http://example.com)', NONE, s:LoosePatternSet)
-    if ret isnot NONE
-        ...
-    endif
+	" Ignore trailing string after URI.
+	let NONE = []
+	let ret = URI.new_from_seq_string(
+	\               'http://example.com)', NONE, s:LoosePatternSet)
+	if ret isnot NONE
+	    ...
+	endif
 <
 
 get({component})			*Vital.Web.URI-PatternSet.get()*
 
-    Returns each component definition.
+	Returns each component definition.
 >
-    let s:PatternSet = s:URI.new_default_pattern_set()
-    echo s:PatternSet.get('scheme')
+	let s:PatternSet = s:URI.new_default_pattern_set()
+	echo s:PatternSet.get('scheme')
 <
 Listing all customizable components here (alphabetic order).
 NOTE: DON'T call these methods directly.
diff --git a/doc/vital/Web/URI/HTTP.txt b/doc/vital/Web/URI/HTTP.txt
new file mode 100644
index 000000000..a9ed0b51e
--- /dev/null
+++ b/doc/vital/Web/URI/HTTP.txt
@@ -0,0 +1,43 @@
+*vital/Web/URI/HTTP.txt*		http scheme handler for Web.URI
+
+Maintainer: tyru <tyru.exe@gmail.com>
+
+==============================================================================
+CONTENTS				*Vital.Web.URI.HTTP-contents*
+
+INTRODUCTION			|Vital.Web.URI.HTTP-introduction|
+INTERFACE			|Vital.Web.URI.HTTP-interface|
+  Functions			|Vital.Web.URI.HTTP-functions|
+
+==============================================================================
+INTRODUCTION				*Vital.Web.URI.HTTP-introduction*
+
+*Vital.Web.URI.HTTP* is a http scheme handler for |Vital.Web.URI|.
+
+==============================================================================
+INTERFACE				*Vital.Web.URI.HTTP-interface*
+------------------------------------------------------------------------------
+FUNCTIONS				*Vital.Web.URI.HTTP-functions*
+
+canonicalize({uri})		*Vital.Web.URI.HTTP.canonicalize()*
+	Canonicalizes {uri}. {uri} is a |Vital.Web.URI-URI| object.
+
+	* Set '/' to its path if its path is empty
+	* If its port is the same as a default port of http scheme (80),
+	  make the URI's port empty
+
+	For example, the following four URIs are equivalent:
+	* http://example.com
+	* http://example.com/
+	* http://example.com:/
+	* http://example.com:80/
+	This function canonicalizes them to http://example.com/ .
+
+	ref. https://tools.ietf.org/html/rfc3986#section-6.2.3
+
+default_port()
+					*Vital.Web.URI.HTTP.default_port()*
+	Returns a string of a default port of http scheme ("80").
+
+==============================================================================
+vim:tw=78:fo=tcq2mM:ts=8:ft=help:norl
diff --git a/doc/vital/Web/URI/HTTPS.txt b/doc/vital/Web/URI/HTTPS.txt
new file mode 100644
index 000000000..83b4b1b49
--- /dev/null
+++ b/doc/vital/Web/URI/HTTPS.txt
@@ -0,0 +1,31 @@
+*vital/Web/URI/HTTPS.txt*		https scheme handler for Web.URI
+
+Maintainer: tyru <tyru.exe@gmail.com>
+
+==============================================================================
+CONTENTS				*Vital.Web.URI.HTTPS-contents*
+
+INTRODUCTION			|Vital.Web.URI.HTTPS-introduction|
+INTERFACE			|Vital.Web.URI.HTTPS-interface|
+  Functions			|Vital.Web.URI.HTTPS-functions|
+
+==============================================================================
+INTRODUCTION				*Vital.Web.URI.HTTPS-introduction*
+
+*Vital.Web.URI.HTTPS* is a https scheme handler for |Vital.Web.URI|.
+
+==============================================================================
+INTERFACE				*Vital.Web.URI.HTTPS-interface*
+------------------------------------------------------------------------------
+FUNCTIONS				*Vital.Web.URI.HTTPS-functions*
+
+canonicalize({uri})		*Vital.Web.URI.HTTPS.canonicalize()*
+	This simply invokes |Vital.Web.URI.HTTP.canonicalize()| with a {uri}
+	argument.
+
+default_port()
+					*Vital.Web.URI.HTTPS.default_port()*
+	Returns a string of a default port of https scheme ("443").
+
+==============================================================================
+vim:tw=78:fo=tcq2mM:ts=8:ft=help:norl