Just to note the reasoning why they've promised that because I thought it was kinda interesting: https://html.spec.whatwg.org/multipage/custom-elements.html#va

Just to note the reasoning why they've promised that because I thought it was kinda interesting: https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name https://html.spec.whatwg.org/multipage/custom-elements.html#... Tag names with at least one hypen and two words either side are reserved for custom element use... with a few exceptions that I assume were part of the HTML/svg/mathml spec before the custom element registry. - annotation-xml - color-profile - font-face - font-face-src - font-face-uri - font-face-format - font-face-name - missing-glyph