[1] 
>    A [DFN@en[number value]] is a [[member]] of the [[type]] [CODE(JS)@en[[[Number]]]]
and is a direct representation of a [[number]].

;; [CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) <http://bclary.com/2004/11/07/#a-4.3.19>

[2]
>    The [[type]] [DFN[[CODE(JS)@en[[[Number]]]]]] is a [[set]] of [[values]] representing [[numbers]].
In [[ECMAScript]], the [[set]] of [[values]] represents the [[double-precision 64-bit format IEEE 754 values]]
including the special “[[Not-a-Number]]” ([[NaN]]) [[values]], [[positive infinity]], and [[negative infinity]].

;;[CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) <http://bclary.com/2004/11/07/#a-4.3.20>

[3]
>    A [DFN[[CODE(JS)@en[Number]] object]] is a [[member]] of the [[type]] [CODE(JS)@en[[[Object]]]] and is an [[instance]]
of the [[built-in]] [CODE(JS)@en[[[Number]]]] [[object]]. That is, a [[[CODE(JS)@en[Number]] object]] is created by using
the [CODE(JS)@en[[[Number]]]] [[constructor]] in a [CODE(JS)@en[[[new]]]] [[expression]], supplying a [[number]] as an
[[argument]]. The resulting [[object]] has an implicit (unnamed) [[property]] that is the [[number]]. 
A [[[CODE(JS)@en[Number]] object]] can be coerced to a [[number]] [[value]] by calling the 
[CODE(JS)@en[[[Number]]]] [[constructor]] as a [[function]] (15.7.1).

;;[CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) <http://bclary.com/2004/11/07/#a-4.3.21>


[FIG(quote)[
[FIGCAPTION[
[5] [CITE@en[Safari 9.0]]
([TIME[2015-11-04 23:30:59 +09:00]] 版)
<https://developer.apple.com/library/safari/releasenotes/General/WhatsNewInSafari/Articles/Safari_9.html#//apple_ref/doc/uid/TP40014305-CH9-SW27>
]FIGCAPTION]

> The following ECMAScript 6 content is now supported by Safari:
> Number Object

]FIG]


[6] [CITE@en[Write structured clone algorithm in terms of ECMAScript · whatwg/html@bfb960c]]
([TIME[2016-03-02 16:44:42 +09:00]] 版)
<https://github.com/whatwg/html/commit/bfb960c938580c95e77365e614218b952f96375b>

[7] [CITE@en[Breaking: refactor structured clone into serialize/deserialize]]
([[domenic]]著, [TIME[2017-03-21 06:09:33 +09:00]])
<https://github.com/whatwg/html/commit/97d644c97335956610a31e8ad98d1a388c063e84>

[4] [CITE@en[Editorial: improve language used around real numeric values. (#388)]]
([[tobie]]著, [TIME[2017-07-29 07:26:33 +09:00]])
<https://github.com/heycam/webidl/commit/79cfa440c3e1e77349640667efdda4feaea637c2>

[8] [CITE@en[22888 – 4.2.{14,15}: "has the same numeric value"]]
([TIME[2017-07-29 13:30:39 +09:00]])
<https://www.w3.org/Bugs/Public/show_bug.cgi?id=22888>

[9] [CITE@en[Editorial: improve language used around real numeric values. by tobie · Pull Request #388 · heycam/webidl]]
([TIME[2017-07-29 13:30:45 +09:00]])
<https://github.com/heycam/webidl/pull/388>