The Zone Rail

A drawing frame is divided into zones — letters down one edge, numbers along the other — so that two people on a phone call can agree on where they are looking. “The bracket in C4.” It is a coordinate system for a conversation.

What it does here

This theme keeps the letters and gives them a job: one zone per top-level heading, in document order, each one a link. The rail you can see down the left edge of this page has three letters because this post has three ## headings. Scroll, and the current one is marked.

That makes the rail a table of contents that costs no vertical space — it lives in the frame margin, which was otherwise empty ruling.

When it does not render

This is the part worth stating plainly, because it is where the metaphor could have gone wrong: a page with nothing to index gets no rail at all.

• A profile or landing page has no ## headings, so no rail.
• A short note written as one continuous argument has none either — and that is a legitimate way to write, not a defect to route around.

Lettering an empty field would be a drawing that claims a structure it does not have. An empty zone rail is worse than no zone rail.

Headings and anchors

Every heading gets an anchor link, revealed on hover and on keyboard focus:

## When it does not render

The render hook that adds it lives in layouts/_markup/render-heading.html. Because it is a render hook rather than JavaScript, the anchors exist in the HTML as shipped — they work with scripting off, and they survive being saved to a file.