[2] >>1 では Document
, Element
, DocumentFragment
の子孫の直列化が規定されています。
[3] XSLT and XQuery Serialization 3.1 () <https://www.w3.org/TR/2017/REC-xslt-xquery-serialization-31-20170321/#html-output>
[4] Update customized built-in elements is="" interaction (domenic著, ) <https://github.com/whatwg/html/commit/e5dc6bf18f356225d90decc47ac6ed3be94728a7>
[5] Update customized built-in elements is="" interaction by domenic · Pull Request #3444 · whatwg/html () <https://github.com/whatwg/html/pull/3444>