The NEXTID Tag

A head element whose only job was to tell your HTML editor what to name the next anchor.

In 2026: Dead, and almost nobody ever saw it alive. NEXTID carried a counter for the editor that wrote the page, so the next generated anchor got a fresh name; browsers were told to ignore it, and they all do, so the tag below renders nothing. It was in the first HTML document ever specified and survived, deprecated, into HTML 2.0. HTML 3.2 dropped it.

Where it came from: HTML Tags, Tim Berners-Lee, 1991. Still in HTML 2.0 (RFC 1866), 1995, as an editor-only relic. Gone from HTML 3.2.
HTML Tags, 1991 ↗RFC 1866 ↗

<!-- The whole feature: -->
<nextid n="z20">

<p style="font:13px Verdana">Nothing renders above, and nothing ever did: NEXTID
spoke to your HTML editor, not to you. The editor read it, named its next
generated anchor z20, and wrote the counter back as z21.</p>