Addenda

A small WordPress plugin that brings four iA Writer authoring conventions to the front end: ==highlights==, {{TOC}}, H2–H3 anchors, and [^inline footnotes].

Features

Highlights

Wrap text in ==double equals== to render it as <mark>.

This is ==highlighted== text.

Works inside paragraphs, list items, blockquotes, and headings. Skipped inside <code> and <pre> blocks.

Also runs on excerpts and text widgets via the the_excerpt and widget_text filters.

Table of Contents

Place {{TOC}} on its own line anywhere in a post to insert a linked, nested <nav> block built from all H2 and H3 headings in the content.

{{TOC}}

## Introduction

## Installation

### Requirements

## Usage

• Nesting mirrors heading level (H2 = top level, H3 = indented under its parent H2)
• Heading slugs are computed from heading text via sanitize_title(); duplicate headings get a -2, -3 suffix
• Stripped from RSS feeds automatically
• Skipped when {{TOC}} appears inside a code span or block

H2–H3 Anchors

Not specifically iA Writer but pairs with Table fo Contents: All H2 and H3 headings get an id attribute automatically so they can be linked to directly. No markup required.

To set a custom anchor instead of the auto-generated slug, add {#your-id} at the end of the heading in your editor:

## Installation {#install}

That heading renders as <h2 id="install">Installation</h2>. Headings that already have an id are left untouched.

Inline Footnotes

Write footnote text directly in the flow of prose using [^...] — no separate reference block needed.

This claim needs a source.[^The source is a 2019 paper by Smith et al.]

Renders as a numbered superscript linked to a footnote list appended at the end of the post. Back-links (↩) are included on screen and omitted from RSS feeds.

Multiple footnotes in one post are numbered in document order.

Installation

1. Copy addenda.php into wp-content/plugins/addenda/
2. Activate the plugin from the WordPress admin

No other configuration needed.

Styling

The plugin outputs semantic HTML. Add CSS to your theme to style it.

<mark> is a standard HTML element — style it with mark { ... }.

Notes

• All four features are skipped inside <code> and <pre> blocks, so you can document the syntax itself without it expanding.
• The plugin hooks into the_content at priority 20, after most other content filters run.
• Only H2 and H3 headings are anchored and included in the TOC. H1, H4, and below are untouched.