Ah, I just checked, and no you can't. So I guess that's a third difference. Than...

spiralx · on May 31, 2019

And thinking about it weren't value-less attributes also illegal? I remember doing a lot of

    <button disabled="disabled">...</button>

in XHTML, instead of

    <button disabled>...</button>

in HTML.

Even SGML has problems with expressing an attribute like that from what I remember reading of someone's attempt to specify HTML 5 using an SGML DTD.