Template placeholders

Overview

A placeholder is written as {{NAME}} and is replaced during HTML rendering.

This allows one Mechdown source document to be rendered into different layouts by swapping shims while keeping content semantics the same.

Core placeholders

• {{STYLESHEET}} — Injected CSS content.

• {{TITLE}} — Document title text.

• {{AUTHOR}} — Inline author paragraph from title front matter.

• {{DATE}} — Inline date paragraph from title front matter.

• {{KICKER}} — Inline kicker paragraph from title front matter.

• {{NEXT}} — Inline next-link paragraph from title front matter.

• {{PREVIOUS}} — Inline previous-link paragraph from title front matter.

• {{HERO}} — Hero media/content from the title block.

• {{SUMMARY}} — Synopsis content from the title block.

• {{TOC}} — Generated table of contents.

• {{ABSTRACT}} — Content from %% abstract blocks.

• {{INTRO}} — Unsectioned intro content before the first numbered section.

• {{CONTENTS}} — Sectioned document body contents.

• {{CONTENT}} — Alias for {{CONTENTS}}.

• {{CITED}} — Works Cited markup (when citations are present).

• {{SECTION#}} — Specific numbered section slot ({{SECTION1}}, {{SECTION2}}, ...).

Interactive placeholders

These placeholders support browser-side Mech runtime integration.

• {{CODE}} — Base64+compressed serialized program payload (when built with serde support). This is used by web runtime bootstrap code to reconstruct and run the page program.

• {{REPL}} — Default REPL mount markup:

<div class="console-scroll mech-repl hidden" id="mech-output"></div>

The web runtime expects a mount with id mech-output when calling attach_repl.

### Reactive variable placeholders

You can embed live interpreter variables directly in a template placeholder:

• {{VAR:x}} — Reads variable x from the default interpreter.

• {{VAR:x@foo}} — Reads variable x from interpreter foo.

These bindings are reactive. If x changes in Mech, the rendered value in the

document updates automatically.