Ask HN: What's a minimal subset of HTML that works everywhere?

Please post a set of tags that is guaranteed to work on +everything from the early days of the web, with some justification if it's a contentious case. Imagine no CSS, and no JavaScript. It's okay if it looks like a BBS (or prior), that's the point.

Your subset must likely work on differently-smart phones, and affordable smartphones popular in super-growth economic regions. You may also find it easier to post tags that can't be supported, rather than those that can, and assume that deprecated tags (like 'blink') are excluded by default. This is also ok. If something can be left out (its markup quality can be reproduced by another tag or combination) then it works to leave it out. This is the minimum viable subset of HTML that works everywhere. You might call it HTML 0, or HTMML (min) but maybe it's closer to HTML 1.618 -- an elegantly proportioned HTML with not an inch extra anywhere.

Finally, it's less important that it be "standards based" than that it works on the majority of devices. Remember when an Apple ][ rendered HN? That should be achievable with your subset. And remember "works" doesn't here mean pretty. It just means : displays information in a comprehensible way with the minimum amount of tags. All serious submissions appreciated -- it's not longer April 1 in my tz. :)

+feel free to specify your everything. It's probably okay as long as it's reasonably inclusive.