Modes

Processor Modes

Apex supports multiple processor modes, each optimized for compatibility with different Markdown flavors.

Overview

Mode	Description	Default ID Format
unified	All features enabled	GFM
quarto	Pandoc/Quarto markdown	GFM
gfm	GitHub Flavored Markdown	GFM
mmd	MultiMarkdown compatibility	MultiMarkdown
kramdown	Kramdown compatibility	Kramdown
commonmark	Pure CommonMark spec	GFM

Unified Mode (Default)

Command: apex document.md or apex --mode unified document.md

Unified mode enables all features from all other modes. This is the default mode.

Enabled Features

• ✅ Tables (GFM style)
• ✅ Strikethrough (~~text~~)
• ✅ Task lists (- [ ] and - [x])
• ✅ Autolinks (URLs and emails)
• ✅ Footnotes (reference and inline styles)
• ✅ Definition lists
• ✅ Smart typography
• ✅ Math support ($inline$ and $$display$$)
• ✅ Superscript and subscript (x^2^, H~2~O)
• ✅ Wiki links ([[Page]]) - Requires --wikilinks flag (disabled by default)
• ✅ Critic Markup
• ✅ Callouts
• ✅ File includes
• ✅ Metadata blocks (YAML, MMD, Pandoc)
• ✅ Metadata variables ([%key]) - See Metadata Transforms for transform syntax
• ✅ Abbreviations
• ✅ Inline Attribute Lists (IAL), including fenced divs and bracketed spans
• ✅ Relaxed tables (default)
• ✅ Grid tables (Pandoc +---+ syntax) - --grid-tables to enable, --no-grid-tables to disable (off by default)
• ✅ GitHub Emoji / emoji autocorrect (:emoji_name:)
• ✅ Image captions from Markdown image syntax (wrap images with title/alt in <figure>/<figcaption>)

ID Format

• Default: GFM format
• Can be overridden with --id-format

Quarto Mode

Command: apex --mode quarto document.qmd

Pandoc/Quarto markdown compatibility for HTML-oriented documents. See Quarto Mode for syntax, metadata toggles, and limitations.

Enabled Features

• ✅ Quarto callouts (::: {.callout-note})
• ✅ Fenced divs and bracketed spans
• ✅ Raw content ({=html}, {=latex}, etc.)
• ✅ Example lists (@), roman lists, line blocks
• ✅ Code fence attributes, diagram fences ({mermaid}, {dot})
• ✅ Shortcode shim ({{< pagebreak >}}, {{< kbd >}}, {{< include >}})
• ✅ fig-alt, semantic span CSS in standalone output

Disabled vs Unified

• ❌ Marked extensions (page break markers, etc.)
• ❌ Wiki links (unless explicitly enabled)
• ❌ Index syntax (mmark, TextIndex, Leanpub)

GFM Mode

Command: apex --mode gfm document.md

GitHub Flavored Markdown compatibility mode.

Enabled Features

• ✅ Tables
• ✅ Strikethrough
• ✅ Task lists
• ✅ Autolinks
• ✅ Hard line breaks (newlines become <br>)

Disabled Features

• ❌ Footnotes
• ❌ Definition lists
• ❌ Smart typography
• ❌ Math
• ❌ Wiki links
• ❌ Critic Markup
• ❌ Callouts
• ❌ File includes
• ❌ Metadata
• ❌ Abbreviations
• ❌ IAL
• ❌ Relaxed tables

ID Format

• GFM format (cannot be changed)

MultiMarkdown Mode

Command: apex --mode mmd document.md or apex --mode multimarkdown document.md

MultiMarkdown compatibility mode.

Enabled Features

• ✅ Tables
• ✅ Footnotes (reference style)
• ✅ Definition lists
• ✅ Smart typography
• ✅ Math support
• ✅ Metadata blocks (YAML, MMD, Pandoc)
• ✅ Metadata variables ([%key]) - See Metadata Transforms for transform syntax
• ✅ Abbreviations
• ✅ File includes
• ✅ Image captions from Markdown image syntax (wrap images with title/alt in <figure>/<figcaption>)

Disabled Features

• ❌ Strikethrough
• ❌ Task lists
• ❌ Wiki links
• ❌ Critic Markup
• ❌ Callouts
• ❌ IAL
• ❌ Relaxed tables

ID Format

• MultiMarkdown format (cannot be changed)

Kramdown Mode

Command: apex --mode kramdown document.md

Kramdown compatibility mode.

Enabled Features

• ✅ Tables
• ✅ Footnotes (reference and inline styles)
• ✅ Definition lists
• ✅ Smart typography
• ✅ Math support
• ✅ Inline Attribute Lists (IAL)
• ✅ Abbreviations
• ✅ Relaxed tables (default)

Disabled Features

• ❌ Strikethrough
• ❌ Task lists
• ❌ Wiki links
• ❌ Critic Markup
• ❌ Callouts
• ❌ File includes
• ❌ Metadata
• ❌ Autolinks

ID Format

• Kramdown format (cannot be changed)

CommonMark Mode

Command: apex --mode commonmark document.md

Pure CommonMark specification compliance. No extensions.

Enabled Features

• ✅ Basic Markdown only (headers, lists, emphasis, links, code, blockquotes, etc.)

Disabled Features

• ❌ All extensions (tables, footnotes, etc.)

ID Format

• GFM format (for consistency)

Feature Comparison Table

Feature	Unified	GFM	MMD	Kramdown	CommonMark
Tables	✅	✅	✅	✅	❌
Strikethrough	✅	✅	❌	❌	❌
Task Lists	✅	✅	❌	❌	❌
Footnotes	✅	❌	✅	✅	❌
Definition Lists	✅	❌	✅	✅	❌
Smart Typography	✅	❌	✅	✅	❌
Math	✅	❌	✅	✅	❌
Wiki Links	✅*	❌	❌	❌	❌
Critic Markup	✅	❌	❌	❌	❌
Callouts	✅	❌	❌	❌	❌
File Includes	✅	❌	✅	❌	❌
Metadata	✅	❌	✅	❌	❌
Abbreviations	✅	❌	✅	✅	❌
IAL	✅	❌	❌	✅	❌
Relaxed Tables	✅	❌	❌	✅	❌
Image Captions	✅	❌	✅	❌	❌

* Wiki links are available in unified mode but disabled by default. Use --wikilinks to enable.

Choosing a Mode

• Quarto - Use for Pandoc/Quarto .qmd documents and HTML-oriented Quarto markdown
• Unified - Use when you want all features or need compatibility with multiple Markdown flavors
• GFM - Use for GitHub compatibility or when publishing to GitHub
• MMD - Use for MultiMarkdown compatibility or when you need metadata
• Kramdown - Use for Kramdown compatibility or when you need IAL attributes
• CommonMark - Use for strict CommonMark compliance or minimal output

Overriding Mode Defaults

In unified mode, you can enable or disable specific features:

# Unified mode but disable footnotes
apex --mode unified --no-footnotes document.md

# Unified mode but disable math
apex --mode unified --no-math document.md

# Enable wiki links (disabled by default)
apex --mode unified --wikilinks document.md

Related

• Header IDs - How ID formats differ by mode
• Syntax - Syntax available in each mode
• Command Line Options - Mode selection and feature flags