Authors are free to either create any data-* attributes they wish for any purpose, so long as the custom attributes are prefixed with "data-".
Authors are also free to create any (valid) HTML custom element, and to invent custom attributes for those elements.
But this appears to require authors to write invalid HTML.
It'll kind of solve the previous commenter concerns about with writing invalid html. While namespaces are more a xml thing, there are probably many benefits to this approach like querying all attributes from the namespace at once too.
I'll keep this in mind for future iterations!
Here's what the HTML spec[1] says about data-* attributes:
Custom data attributes are intended to store custom data, state, annotations, and similar, private to the page or application, for which there are no more appropriate attributes or elements.
1: https://html.spec.whatwg.org/multipage/dom.html#embedding-cu...