# Special content blocks#

A common use of directives and roles is to designate “special blocks” of your content. This allows you to include more complex information such as warnings and notes, citations, and figures. This section covers a few common ones.

Upgrading from sphinx-panels

Previous versions of Jupyter Book used sphinx-panels to define major UI elements. These now use Sphinx Design instead. Documentation for these UI elements is now in Components and UI elements. See the migration guide and this migration discussion issue for more information.

## MyST syntax extensions#

MyST Markdown has a base syntax that it supports, and additional syntax can be enabled to add extra functionality. By default, Jupyter Book enables a few extra syntax pieces for MyST in order to more closely resemble the Markdown experience in Jupyter Notebooks and interfaces. These extensions are:

dollarmath

To support  and \$ syntax for math blocks. See Math and equations.

linkify

substitution

To allow you to define markdown “variables” and substitute text in using them. See Substitutions and variables in markdown.

colon_fence

To allow you to use ::: fences for admonitions, in order to make them easier to render in interfaces that do not support MyST. See Markdown-friendly directives with :::.

To enable your own syntax extensions, use the following configuration pattern:

parse:
myst_enable_extensions:
- extension-1
- extension-2


Note that this will override the default Jupyter Book extension list. You should include all of the extensions that you want to be enabled.

For a list of syntax extensions in MyST, see the MyST documentation.

## Notes, warnings, and other admonitions#

Let’s say you wish to highlight a particular block of text that exists slightly apart from the narrative of your page. You can use the {note} directive for this.

For example:

{note}
Here is a note!



Note

Here is a note!

There are a number of similarly-styled blocks of text. For example, here is a {warning} block:

Warning

Here’s a warning! It was created with:

{warning}



You can also create dropdown admonitions by adding a dropdown class to an admonition. For example:

For a complete list of options, see the sphinx-book-theme documentation.

### Blocks of text with custom titles#

You can also choose the title of your message box by using the {admonition} directive. For example:

{admonition} Here's your admonition



If you’d like to style these blocks, then use the :class: option. For example:

{admonition} This admonition was styled...
:class: tip
With a tip class!



With a tip class!

### Markdown-friendly directives with :::#

The admonition syntax above utilises the general directives syntax. However, if you’re using an interface that does not support MyST Markdown, it will render as a raw literal block. Many directives contain markdown inside, and if you’d like this markdown to render “normally”, you may also use ::: fences rather than  fences to define the directive. As a result, the contents of the directive will be rendered as markdown.

For example:

:::{note}
This text is **standard** _Markdown_
:::


Note

This text is standard Markdown

Similar to normal directives, these admonitions can also be nested:

::::{important}
:::{note}
This text is **standard** _Markdown_
:::
::::


Important

Note

This text is standard Markdown

Note

You can use this syntax for any kind of directive, though it is generally recommended to use only with directives that contain pure markdown in their content.

### Insert code cell outputs into admonitions#

If you’d like to insert the outputs of running code inside admonition blocks, we recommend using glue functionality. For example, we’ll insert one of the outputs that was glued into the book from the code outputs page.

For example:

{note}
Here's my figure:

{glue:figure} sorted_means_fig



Note

Here’s my figure:

See Store code outputs and insert into content for more information on how to use glue to insert your outputs directly into your content.

Tip

To hide code input and output that generated the variable you are inserting, use the remove_cell tag. See Hide or remove content for more information and other tag options.

A drawback of admonition syntax is that it will not render in interfaces that do not support this syntax (e.g., GitHub). If you’d like to use admonitions that are defined purely with HTML, MyST can parse them via the html_admonitions extension. To use it, first enable it with the following configuration:

parse:
myst_enable_extensions:
# don't forget to list any other extensions you want enabled,
# including those that are enabled by default!


html
<p class="title">This is the **title**</p>
This is the *content*
</div>


<div class="admonition note" name="html-admonition" style="background: lightgreen; padding: 10px">
<p class="title">This is the **title**</p>
This is the *content*
</div>


You should not embed headings (lines starting with #) inside of admonitions, dropdowns, or other content blocks such as this. Sphinx (and thus Jupyter Book) uses headings to define the major top-level sections of a document. For this reason, nesting a heading within a block will cause unpredictable breakage of the document structure.

Do not do this

For example, do not do this:

{note}
## This heading is inside an admonition, and will mess things up!

Don't do this!



To achieve a similar effect, write some bold text instead of using a markdown header.

## Definition lists#

Definition lists are enabled by defining the following setting in your _config.yml:

parse:
myst_enable_extensions:
# don't forget to list any other extensions you want enabled,
# including those that are enabled by default!
- deflist


Definition lists utilise the markdown-it-py deflist plugin, which itself is based on the Pandoc definition list specification.

Here’s an example:

Term 1
: Definition

Term 2
: Definition

Term 1

Definition

Term 2

Definition

From the Pandoc documentation:

Each term must fit on one line, which may optionally be followed by a blank line, and must be followed by one or more definitions. A definition begins with a colon or tilde, which may be indented one or two spaces.

A term may have multiple definitions, and each definition may consist of one or more block elements (paragraphs, code blocks, lists, etc.)

Here is a more complex example, demonstrating some of these features:

Term *with Markdown*
: Definition [with reference](content/definition-lists)

A second paragraph
: A second definition

Term 2
~ Definition 2a
~ Definition 2b

Term 3
:     A code block
: > A quote
: A final definition, that can even include images:

<img src="../images/fun-fish.png" alt="fishy" width="200px">

Term with Markdown

Definition with reference

A second paragraph

A second definition

Term 2

Definition 2a

Definition 2b

Term 3
A code block


A quote

A final definition, that can even include images:

## Quotations and epigraphs#

Quotations and epigraphs provide ways to highlight information given by others.

### Quotations#

Regular quotations are controlled with standard Markdown syntax, i.e., by inserting a caret (>) symbol in front of one or more lines of text. For example:

> Here is a cool quotation.
>
> From me, Jo the Jovyan


Here is a cool quotation.

From me, Jo the Jovyan

### Epigraphs#

Epigraphs draw more attention to a quote and highlight its author. You should keep these relatively short so that they don’t take up too much vertical space. Here’s how an epigraph looks:

{epigraph}
Here is a cool quotation.

From me, Jo the Jovyan



Here is a cool quotation.

From me, Jo the Jovyan

You can provide an attribution to an epigraph by adding -- to the final line, followed by the quote author. For example:

{epigraph}
Here is a cool quotation.

-- Jo the Jovyan



Here is a cool quotation.

—Jo the Jovyan

## Glossaries#

Glossaries allow you to define terms in a glossary so you can then link back to it throughout your content. You can create a glossary with the following syntax:

{glossary}
Term one
An indented explanation of term 1

A second term
An indented explanation of term2


Term one#

An indented explanation of term 1

A second term#

An indented explanation of term2

To reference terms in your glossary, use the {term} role. For example, {term}Term one becomes Term one and {term}A second term becomes A second term.

Note

## Indexes#

Indexes allow you to define index items (terms, phrases, keywords, etc) that are collected in a single page, with links back to their location in your content. This is called the General Index.

When you build your book, a general index page will automatically be generated.

To create a reference / link to your general index, use the genindex keyword. For example:

### The {index} directive#

You can add items to your general index with the {index} directive. It has the following syntax:

{index} Entry name



This will not insert anything into your final page’s content, but will add a link to this section in your general index. For example”

{index} index directive



You can find this term in the index.

#### Add a label to your {index} directive#

You can customize the name for an index entry by setting the :name: parameter. For example:

{index} Index names
:name: index-names



You can then reference this index in your book. For example:

#### Create more complex index entries#

The Sphinx Index-generating markup page describes the full range of indexing possibilites. This includes the ability to construct nested headings using the ; separator to represent a change in index level:

{index} single: Jupyter Book ; installation



Multiple index entry terms can be created from a single reference. For example, we can create entries references ; index terms and index terms ; references from the following entry:

{index} double: references ; index terms



Readers can be directed towards alternative index terms within the index itself by using see or seealso, as in the following example which adds an entry for citations to also refer to bibliographies:

{index} seealso: citations ; bibliographies



### Create index entries with other extensions#

You can also create index entries through the use of other Sphinx extensions. For example, any term you define in a Glossary will also be inserted into the index.

• Create a file in the root of your book called genindex.md.

• It must have a title but the rest can be blank. The title will actually be replaced with Index when your book is built, but it is needed in your source file to avoid errors.

format: jb-book
root: index
chapters:
- file: path/to/chapter1
- file: path/to/chapter2
- file: genindex


## Substitutions and variables in markdown#

Substitutions allow you to define variables in the front-matter of your page, and then insert those variables into your content throughout.

To use a substitution, first add front-matter content to the top of a page like so:

---
substitutions:
key1: "I'm a **substitution**"
key2: |
{note}
{{ key1 }}

fishy: |
{image} img/fun-fish.png
:alt: fishy
:width: 200px

---


You can use these substitutions inline or as blocks, and you can even nest substitutions in other substitutions (but circular references are prohibited):

Inline: {{ key1 }}

Block level:

{{ key2 }}


Inline: I’m a substitution

Block level:

Note

I’m a substitution

You can also insert substitutions inside of other markdown structures like tables:

| col1     | col2      |
| -------- | --------- |
| {{key2}} | {{fishy}} |


col1

col2

Note

I’m a substitution

### Define substitutions for your whole book#

You can also define book-level substitution variables with the following configuration:

parse:
myst_substitutions:
key: value


These substitutions will be available throughout your book. For example, the global substitution key my-global-substitution is defined in this book’s _config.yml file, and it produces: My global value!.

### Formatting substitutions#

MyST substitutions use Jinja templates in order to substite in key / values. This means that you can apply any standard Jinja formatting to your substitutions. For example, you can replace text in your substitutions like so:

The original key1: {{ key1 }}

{{ key1 | replace("a substitution", "the best substitution")}}


The original key1: I’m a substitution

I’m a substitution

## Figures#

You can thoroughly customise the look of figures in your book. See Images and figures for more information.

## Footnotes#

You can include footnotes in your book using standard Markdown syntax. This will include a numbered reference to the footnote in-line, and append the footnote to a list of footnotes at the bottom of the page.

To create a footnote, first insert a reference in-line with this syntax: [^mylabel]. Then, define the text for that label like so:

[^mylabel]: My footnote text.


You can define [^mylabel] anywhere in the page, though its definition will always be placed at the bottom of your built page. For example, here’s a footnote 1 and here’s another one 2. You can click either of them to see the footnotes at the bottom of this page.

1

Here’s the text of my first note.

2

And the text of my second note. Note that you can include Markdown footnote definitions.