[Proposal] (DRAFT) for new outline algorithm

• <main> is the “main” sectioning root. It would be good for visually designing main contents (for instance, using css grid).
• <header>, <aside>, <footer>, and <nav> are the other sectioning roots. These can have sectioning content.
• Other flow elements can’t have <h#> because it is useless or already have one comparable to that (ex. <legend>, <caption> etc.).
• <section>, and <article> remain sectioning content.
• One sectioning [root, content], one child heading. (1)
• Remove <hgroup>.
• Optional: define role="subheading" and reconsider <h>.

(1)

<!-- this make sense -->
<section>
    <h1></h1>
    <section>
        <h1></h1>
    </section>
    .........
</section>

<!-- this is nonsense -->
<section>
    <h1></h1>
    <h1></h1>(x)
    .........
</section>

Why am I banned about editting?