---
title: Code
description: Code blocks can be used to display multiple lines of code. They preserve formatting and provide syntax highlighting when possible. Start and end a code...
url: https://docs-v3-preview.elastic.dev/elastic/docs-builder/pull/2386/syntax/code
---

# Code
Code blocks can be used to display multiple lines of code. They preserve formatting and provide syntax highlighting when possible.

## Code block

Start and end a code block with a code fence. A code fence is a sequence of at least three consecutive backtick characters `````. You can optionally add a language identifier to enable syntax highlighting.
<tab-set>
  <tab-item title="Output">
    ```yaml
    project:
      title: MyST Markdown
      github: https://github.com/jupyter-book/mystmd
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```yaml
    project:
      title: MyST Markdown
      github: https://github.com/jupyter-book/mystmd
    ```
    ```
  </tab-item>
</tab-set>


### Code callouts

There are two ways to add callouts to a code block. When using callouts, you must use one callout format. You cannot combine explicit and magic callouts.

#### Explicit callouts

Add `<\d+>` to the end of a line to explicitly create a code callout.
An ordered list with the same number of items as callouts must follow the code block. If the number of list items doesn’t match the callouts, docs-builder will throw an error.
<tab-set>
  <tab-item title="Output">
    ```yaml
    project:
      license:
        content: CC-BY-4.0 
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```yaml
    project:
      license:
        content: CC-BY-4.0 <1>
    ```

    1. The license
    ```
  </tab-item>
</tab-set>

You can also have one block element in between the code block and the callout list:
<tab-set>
  <tab-item title="Output">
    ```javascript
    var input1 = "World";
    var input2 = "Elastic";

    function render(input) {
        return `Hello, ${input}!`;
    }

    render(input1);
    render(input2);
    ```
    **Outputs**:
    1. `Hello, World!`
    2. `Hello, Elastic!`
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```javascript
    var input1 = "World"; // <1>
    var input2 = "Elastic"; // <2>

    function render(input) {
        return `Hello, ${input}!`;
    }

    render(input1);
    render(input2);
    ```

    **Inputs:**

    1. `World`
    2. `Elastic`

    **Outputs**:

    1. `Hello, World!`
    2. `Hello, Elastic!`
    ```
  </tab-item>
</tab-set>


#### Automatic callouts

If a code block contains code comments in the form of `//` or `#`, callouts are automatically created.
<tab-set>
  <tab-item title="Output">
    ```csharp
    var apiKey = new ApiKey("<API_KEY>");
    var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```csharp
    var apiKey = new ApiKey("<API_KEY>"); // Set up the api key
    var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
    ```
    ```
  </tab-item>
</tab-set>

Code comments must follow code to be hoisted as a callout. For example:
<tab-set>
  <tab-item title="Output">
    ```csharp
    // THIS IS NOT A CALLOUT
    var apiKey = new ApiKey("<API_KEY>");
    var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```csharp
    // THIS IS NOT A CALLOUT
    var apiKey = new ApiKey("<API_KEY>"); // This is a callout
    var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
    ```
    ```
  </tab-item>
</tab-set>


#### Align callouts

You can align callouts with spaces.
<tab-set>
  <tab-item title="Output">
    ```yaml
    foo: 1       
    barbar: 2    
    bazbazbaz: 3 
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```yaml
    foo: 1       <1>
    barbar: 2    <2>
    bazbazbaz: 3 <3>
    ```

    1. Foo
    2. Bar
    3. Baz
    ```
  </tab-item>
</tab-set>


#### Turn off callouts

You can turn off callouts by adding a code block argument `callouts=false`.
<tab-set>
  <tab-item title="Output">
    ```yaml
    project:
      license:
        content: CC-BY-4.0 <1>
    ```

    1. The license
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```yaml callouts=false
    project:
      license:
        content: CC-BY-4.0 <1>
    ```

    1. The license
    ```
  </tab-item>
</tab-set>


### Console code blocks

We document a lot of API endpoints at Elastic. For these endpoints, we support `console` as a language. The term console relates to the dev console in kibana which users can link to directly from these code snippets.
In a console code block, the first line is highlighted as a dev console string and the remainder as json:
<tab-set>
  <tab-item title="Output">
    ```json

    {
      "source": {
        "remote": {
          "host": "<OTHER_HOST_URL>",
          "username": "user",
          "password": "pass"
        },
        "index": "my-index-000001",
        "query": {
          "match": {
            "test": "data"
          }
        }
      },
      "dest": {
        "index": "my-new-index-000001"
      }
    }
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```console
    POST _reindex
    {
      "source": {
        "remote": {
          "host": "<OTHER_HOST_URL>",
          "username": "user",
          "password": "pass"
        },
        "index": "my-index-000001",
        "query": {
          "match": {
            "test": "data"
          }
        }
      },
      "dest": {
        "index": "my-new-index-000001"
      }
    }
    ```
    ```
  </tab-item>
</tab-set>

Console code blocks now support multiple API calls within a single code block. When you have multiple console commands, they are displayed as separate sections within the same block with proper visual separation:
<tab-set>
  <tab-item title="Output">
    ```json

    {
        "from": 1,
        "query": {
            "match_all" {}
        }
    }


    {
        "title": "New Document",
        "content": "This is a sample document"
    }
    ```
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ```console
    GET /mydocuments/_search
    {
        "from": 1,
        "query": {
            "match_all" {}
        }
    }

    POST /mydocuments/_doc
    {
        "title": "New Document",
        "content": "This is a sample document"
    }
    ```
    ```
  </tab-item>
</tab-set>


### Code block substitutions

You can use substitutions to insert reusable values into your code block examples.
Check the [code blocks substitutions syntax](/elastic/docs-builder/pull/2386/syntax/substitutions#code-blocks) for more information.

## Inline code

Use backticks to create an inline code span.
Inline code spans are useful for short code snippets or variable names.

### Inline code in a paragraph

<tab-set>
  <tab-item title="Output">
    This `code` is inline.
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    This `code` is inline.
    ```
  </tab-item>
</tab-set>


### Inline code in a heading

<tab-set>
  <tab-item title="Output">
    ## This `code` is in a heading.
  </tab-item>

  <tab-item title="Markdown">
    ```markdown
    ## This `code` is in a heading.
    ```
  </tab-item>
</tab-set>


## Supported languages

Refer to [hljs.ts](https://github.com/elastic/docs-builder/blob/main/src/Elastic.Documentation.Site/Assets/hljs.ts)
for a complete list of supported languages.