Is MDN wrong about the html main tag in their documentation?

Question

I was stumbling about the MDN documents and saw that they said it was ok to use the main tag in article elements, while W3 says it should not be a decedent at all within the article element.

MDN:

You can use multiple <main> elements within the same page when it makes sense to do so. For instance, if you have a page presenting multiple articles (each inside an <article> element,

W3:

Note: There must not be more than one <main> element in a document. The <main> element must NOT be a descendant of an <article>, <aside>, <footer>, <header>, or <nav> element.

I want others to help me confirm if this is right and if so how can I contact MDN about this? I looked at their github and there is no place to report issues, or the contact us page is just about firefox, legalities of using the logo, or donating. Which is the right channel for the documentation support?

Answer 1

In the top infobox on the MDN page:

Permitted parents: Any element that accepts flow content (WHATWG). However, the W3C specification doesn't allow <main> to be used as a descendent of <article>, <aside>, <footer>, <header>, or <nav>.

Basically, the W3C and WHATWG specifications disagree. Typically, the WHATWG spec is what browsers follow, though there isn't much reason to place a <main> as a descendent of one of the others listed.