[1]
[CITE[formタグ内のinput type=imageのdisabledを有効化したい]] 
<http://chaichan.web.infoseek.co.jp/qanda/qa6413.htm>

[CODE(DOM)@en[[VAR(DOMi)[[[HTMLFormElement]]]].[CODE(DOMa)[elements]]]]
に [CODE(HTMLa)@en[[[type]]]] [CODE(HTML)@en[[[image]]]]
の [CODE(HTMLe)@en[[[input]]]] 要素が含まれない。

[2]
[CITE@en[Web Forms 2.0]] 
<http://www.whatwg.org/specs/web-forms/current-work/#elements>

仕様も >>1 を反映している。が、その一方で [CODE(HTMLe)@en[[[output]]]]
とか追加しちゃっていいのか?

[4] >>2 [CODE(HTMLe)@en[[[output]]]] は新規に追加されたものだから、互換性に影響しないからいいのでしょう。
[CODE(HTML)@en[[[<input type=image>]]]] は今まで含まれていなかったので、
急に含まれるようになっては困る。

[3] [CITE@en[Web Applications 1.0 r8446     Turns out browsers reset the form owner not just when a node is taken from a document, but also when it's taken from a subtree. which makes sense.]]
( ([TIME[2014-01-31 06:51:00 +09:00]] 版))
<http://html5.org/tools/web-apps-tracker?from=8445&to=8446>


[5] [CITE[IRC logs: freenode / #whatwg / 20140222]]
( ([TIME[2014-02-23 13:12:52 +09:00]] 版))
<http://krijnhoetmer.nl/irc-logs/whatwg/20140222>

[6] [[IE]]11 は [CODE(HTMLe)@en[[[output]]]] [[要素]]を含めないようです。
[TIME[2015-09-29T09:24:57.900Z]]

[7] [CITE@en-GB-x-Hixie[Web Forms 2.0]]
([TIME[2009-01-05 20:07:15 +09:00]] 版)
<http://www.whatwg.org/specs/web-forms/current-work/#elements0>

[8] [CITE@en[Remove legacycaller from two collections · whatwg/html@834a858]] ([TIME[2015-09-30 23:00:16 +09:00]] 版) <https://github.com/whatwg/html/commit/834a8589d2df1977ee8cb1e8b277fa87d5a69a0b>

[9] [CITE@en[Fix #200: make <fieldset>.elements return a HTMLCollection · whatwg/html@934887d]]
([TIME[2016-01-09 11:39:42 +09:00]] 版)
<https://github.com/whatwg/html/commit/934887d313305448b7ba6dd3af6f7434e1b600c8>

[10] [CITE@en[Fix #200: make <fieldset>.elements return a HTMLCollection · whatwg/html@934887d]]
([TIME[2016-01-09 11:39:51 +09:00]] 版)
<https://github.com/whatwg/html/commit/934887d313305448b7ba6dd3af6f7434e1b600c8>

[11] [CITE@en[Remove inaccurate fieldset ref in HTMLFormControlsCollection · whatwg/html@b88afb6]]
([TIME[2016-01-12 11:32:28 +09:00]] 版)
<https://github.com/whatwg/html/commit/b88afb63ad1d4b0def27c4561e267f15017bdc8a>

[12] [CITE@en[Editorial: synchronize with the DOM Standard · whatwg/html@21c6ec7]]
([TIME[2016-03-20 18:10:53 +09:00]] 版)
<https://github.com/whatwg/html/commit/21c6ec77594eb89b836d4872222f5916910967fd>

[13] [CITE@en[Remove <label form> and redefine label.form IDL attribute]]
( ([[zcorpan]]著, [TIME[2016-04-28 22:48:52 +09:00]]))
<https://github.com/whatwg/html/commit/99f0f1ae017523276ea4dd5784ec63a23a23834d>

[14] [CITE@en[Remove <keygen>]]
([[domenic]]著, [TIME[2017-01-14 07:03:02 +09:00]])
<https://github.com/whatwg/html/commit/5baa38720f6e83c94a50018c4565808ad548d69c>

[15] [CITE@en[Make form.elements rooted at the document, not the form]]
([[hzr]]著, [TIME[2017-06-16 05:28:09 +09:00]])
<https://github.com/whatwg/html/commit/821229b6ec15503b4d692728752390e4c18a6777>

[16] [CITE@en[Shadow: fix definition of form.elements]]
([[hzr]]著, [TIME[2017-08-16 18:34:30 +09:00]])
<https://github.com/whatwg/html/commit/f04efab424301b3c6b074ca1ca7e99160346af2b>

[17] [CITE@en[form.elements and shadow trees · Issue #2795 · whatwg/html]]
([TIME[2017-08-17 13:24:43 +09:00]])
<https://github.com/whatwg/html/issues/2795>

[18] [CITE@en[Fix definition of form.elements by hzr · Pull Request #2825 · whatwg/html]]
([TIME[2017-08-17 13:24:56 +09:00]])
<https://github.com/whatwg/html/pull/2825>

[19] [[Edge]] では [CODE[elements]] に [CODE[form=""]] によって関連付けられた[[フォームコントロール]]が含まれるにも関わらず、
[[named index]] でアクセスできないようです。
[TIME[2018-12-19T04:58:13.200Z]]