title: Changelog
toc_depth: 2

# Python-Markdown Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). See the [Contributing Guide](contributing.md) for details.

## [3.7] -- 2024-08-16

### Changed

#### Refactor `abbr` Extension

A new `AbbrTreeprocessor` has been introduced, which replaces the now deprecated
`AbbrInlineProcessor`. Abbreviation processing now happens after Attribute Lists,
avoiding a conflict between the two extensions (#1460).

The `AbbrPreprocessor` class has been renamed to `AbbrBlockprocessor`, which
better reflects what it is. `AbbrPreprocessor` has been deprecated.

A call to `Markdown.reset()` now clears all previously defined abbreviations.

Abbreviations are now sorted by length before executing `AbbrTreeprocessor`
to ensure that multi-word abbreviations are implemented even if an abbreviation
exists for one of those component words. (#1465)

Abbreviations without a definition are now ignored. This avoids applying
abbr tags to text without a title value.

Added an optional `glossary` configuration option to the abbreviations extension.
This provides a simple and efficient way to apply a dictionary of abbreviations
to every page.

Abbreviations can now be disabled by setting their definition to `""` or `''`.
This can be useful when using the `glossary` option.


### Fixed

* Fixed links to source code on GitHub from the documentation (#1453).

## [3.6] -- 2024-03-14

### Changed

#### Refactor TOC Sanitation

* All postprocessors are now run on heading content.
* Footnote references are now stripped from heading content. Fixes #660.
* A more robust `striptags` is provided to convert headings to plain text.
  Unlike, the `markupsafe` implementation, HTML entities are not unescaped.
* The plain text `name`, rich `html`, and unescaped raw `data-toc-label` are
  saved to `toc_tokens`, allowing users to access the full rich text content of
  the headings directly from `toc_tokens`.
* The value of `data-toc-label` is sanitized separate from heading content
  before being written to `name`. This fixes a bug which allowed markup through
  in certain circumstances. To access the raw unsanitized data, retrieve the
  value from `token['data-toc-label']` directly.
* An `html.unescape` call is made just prior to calling `slugify` so that
  `slugify` only operates on Unicode characters. Note that `html.unescape` is
  not run on `name`, `html`, or `data-toc-label`.
* The functions `get_name` and `stashedHTML2text` defined in the `toc` extension
  are both **deprecated**. Instead, third party extensions should use some
  combination of the new functions `run_postprocessors`, `render_inner_html` and
  `striptags`.

### Fixed

* Include `scripts/*.py` in the generated source tarballs (#1430).
* Ensure lines after heading in loose list are properly detabbed (#1443).
* Give smarty tree processor higher priority than toc (#1440).
* Permit carets (`^`) and square brackets (`]`) but explicitly exclude
  backslashes (`\`) from abbreviations (#1444).
* In attribute lists (`attr_list`, `fenced_code`), quoted attribute values are
  now allowed to contain curly braces (`}`) (#1414).

## [3.5.2] -- 2024-01-10

### Fixed

* Fix type annotations for `convertFile` - it accepts only bytes-based buffers.
  Also remove legacy checks from Python 2 (#1400)
* Remove legacy import needed only in Python 2 (#1403)
* Fix typo that left the attribute `AdmonitionProcessor.content_indent` unset
  (#1404)
* Fix edge-case crash in `InlineProcessor` with `AtomicString` (#1406).
* Fix edge-case crash in `codehilite` with an empty `code` tag (#1405).
* Improve and expand type annotations in the code base (#1401).
* Fix handling of bogus comments (#1425).

## [3.5.1] -- 2023-10-31

### Fixed

* Fix a performance problem with HTML extraction where large HTML input could
  trigger quadratic line counting behavior (#1392).
* Improve and expand type annotations in the code base (#1394).

## [3.5] -- 2023-10-06

### Added

#### Add `permalink_leading` configuration option to the toc extension (#1339)

A new boolean option `permalink_leading` controls the position of the permanent
link anchors generated with `permalink`. Setting `permalink_leading` to `True`
will cause the links to be inserted at the start of the header, before any other
header content. The default behavior for `permalink` is to append permanent
links to the header, placing them after all other header content.

### Changed

* Add support for cPython version 3.12 (and PyPy 3.10) and drop support for
  Python version 3.7 (#1357).
* Refactor changelog to use the format defined at <https://keepachangelog.com/>.
* Update the list of empty HTML tags (#1353).
* Add customizable TOC title class to TOC extension (#1293).
* Add API documentation of the code base which is generated by
  [mkdocstrings](https://mkdocstrings.github.io/) (#1220).

### Fixed

* Fix a corner case in admonitions where if an indented code block was provided
  as the first block, the output would be malformed (#1329).

## [3.4.4] -- 2023-07-25

### Fixed

* Add a special case for initial `'s` to smarty extension (#1305).
* Unescape any backslash escaped inline raw HTML (#1358).
* Unescape backslash escaped TOC token names (#1360).

## [3.4.3] -- 2023-03-23

### Fixed

* Restore console script (#1327).

## [3.4.2] -- 2023-03-22

### Fixed
* Officially support Python 3.11.
* Improve standalone * and _ parsing (#1300).
* Consider `<html>` HTML tag a block-level element (#1309).
* Switch from `setup.py` to `pyproject.toml`.

## [3.4.1] -- 2022-07-15

### Fixed

* Fix an import issue with `importlib.util` (#1274).

## [3.4] -- 2022-07-15

### Changed

#### The `tables` extension now uses a `style` attribute instead of an `align` attribute for alignment.

The [HTML4 spec](https://www.w3.org/TR/html4/present/graphics.html#h-15.1.2)
specifically deprecates the use of the `align` attribute and it does not appear
at all in the [HTML5
spec](https://www.w3.org/TR/html53/tabular-data.html#attributes-common-to-td-and-th-elements).
Therefore, by default, the [tables](extensions/tables.md) extension will now use
the `style` attribute (setting just the `text-align` property) in `td` and `th`
blocks.

The former behavior is available by setting the `use_align_attribute`
configuration option to `True` when enabling the extension.

For example, to configure the old `align` behavior:

```python
from markdown.extensions.tables import TableExtension

markdown.markdown(src, extensions=[TableExtension(use_align_attribute=True)])
```

#### Backslash unescaping moved to Treeprocessor (#1131).

Unescaping backslash escapes has been moved to a Treeprocessor, which  enables
proper HTML escaping during serialization. However, it is recognized that
various third-party extensions may be calling the old class at
`postprocessors.UnescapePostprocessor`. Therefore, the old class remains in the
code base, but has been deprecated and will be removed in a future release. The
new class `treeprocessors.UnescapeTreeprocessor` should be used instead.

#### Previously deprecated objects have been removed

Various objects were deprecated in version 3.0 and began raising deprecation
warnings (see the [version 3.0 release notes](#30-2018-09-21) for details). Any of those objects
which remained in version 3.3 have been removed from the code base in version 3.4
and will now raise errors. The relevant objects are listed below.


| Deprecated Object                      | Replacement Object                  |
|----------------------------------------|-------------------------------------|
| `markdown.version`                     | `markdown.__version__`              |
| `markdown.version_info`                | `markdown.__version_info__`         |
| `markdown.util.etree`                  | `xml.etree.ElementTree`             |
| `markdown.util.string_type`            | `str`                               |
| `markdown.util.text_type`              | `str`                               |
| `markdown.util.int2str`                | `chr`                               |
| `markdown.util.iterrange`              | `range`                             |
| `markdown.util.isBlockLevel`           | `markdown.Markdown().is_block_level`|
| `markdown.util.Processor().markdown`   | `markdown.util.Processor().md`      |
| `markdown.util.Registry().__setitem__` | `markdown.util.Registry().register` |
| `markdown.util.Registry().__delitem__` |`markdown.util.Registry().deregister`|
| `markdown.util.Registry().add`         | `markdown.util.Registry().register` |

In addition, the `md_globals` parameter of
`Markdown.extensions.Extension.extendMarkdown()` is no longer recognized as a
valid parameter and will raise an error if provided.

### Added

* Some new configuration options have been added to the
  [footnotes](extensions/footnotes.md) extension (#1218):

    * Small refactor of the `BACKLINK_TITLE` option; The use of `format()`
      instead of "old" `%d` formatter allows one to specify text without the
      need to have the number of the footnote in it (like footnotes on
      Wikipedia for example). The modification is backward compatible so no
      configuration change is required.

    * Addition of a new option `SUPERSCRIPT_TEXT` that allows one to specify a
      custom placeholder for the footnote itself in the text.
      Ex: `[{}]` will give `<sup>[1]</sup>`, `({})` will give `<sup>(1)</sup>`,
      or by default, the current behavior: `<sup>1</sup>`.

* The [Table of Contents](extensions/toc.md) extension now accepts a
  `toc_class` parameter which can be used to set the CSS class(es) on the
  `<div>` that contains the Table of Contents (#1224).

* The CodeHilite extension now supports a `pygments_formatter` option that can
  be set to a custom formatter class (#1187).

    - If `pygments_formatter` is set to a string (ex: `'html'`), Pygments'
      default formatter by that name is used.
    - If `pygments_formatter` is set to a formatter class (or any callable
      which returns a formatter instance), then an instance of that class is
      used.

    The formatter class is now passed an additional option, `lang_str`, to
    denote the language of the code block (#1258). While Pygments' built-in
    formatters will ignore the option, a custom formatter assigned to the
    `pygments_formatter` option can make use of the `lang_str` to include the
    code block's language in the output.

### Fixed

* Extension entry-points are only loaded if needed (#1216).
* Added additional checks to the `<pre><code>` handling of
  `PrettifyTreeprocessor` (#1261, #1263).
* Fix XML deprecation warnings.

## [3.3.7] -- 2022-05-05

### Fixed

* Disallow square brackets in reference link ids (#1209).
* Retain configured `pygments_style` after first code block (#1240).
* Ensure fenced code attributes are properly escaped (#1247).

## [3.3.6] -- 2021-11-17

### Fixed

* Fix a dependency issue (#1195, #1196).

## [3.3.5] -- 2021-11-16

### Fixed

* Make the `slugify_unicode` function not remove diacritical marks (#1118).
* Fix `[toc]` detection when used with `nl2br` extension (#1160).
* Re-use compiled regex for block level checks (#1169).
* Don't process shebangs in fenced code blocks when using CodeHilite (#1156).
* Improve email address validation for Automatic Links (#1165).
* Ensure `<summary>` tags are parsed correctly (#1079).
* Support Python 3.10 (#1124).

## [3.3.4] -- 2021-02-24

### Fixed

* Properly parse unclosed tags in code spans (#1066).
* Properly parse processing instructions in md_in_html (#1070).
* Properly parse code spans in md_in_html (#1069).
* Preserve text immediately before an admonition (#1092).
* Simplified regex for HTML placeholders (#928) addressing (#932).
* Ensure `permalinks` and `anchorlinks` are not restricted by `toc_depth` (#1107).
* Fix corner cases with lists under admonitions (#1102).

## [3.3.3] -- 2020-10-25

### Fixed

* Unify all block-level tags (#1047).
* Fix issue where some empty elements would have text rendered as `None` when using `md_in_html` (#1049).
* Avoid catastrophic backtracking in `hr` regex (#1055).
* Fix `hr` HTML handling (#1053).

## [3.3.2] -- 2020-10-19

### Fixed

* Properly parse inline HTML in md_in_html (#1040 & #1045).
* Avoid crashing when md_in_html fails (#1040).

## [3.3.1] -- 2020-10-12

### Fixed

* Correctly parse raw `script` and `style` tags (#1036).
* Ensure consistent class handling by `fenced_code` and `codehilite` (#1032).

## [3.3] -- 2020-10-06

### Changed

#### The prefix `language-` is now prepended to all language classes by default on code blocks.

The [HTML5
spec](https://www.w3.org/TR/html5/text-level-semantics.html#the-code-element)
recommends that the class defining the language of a code block be prefixed with
`language-`. Therefore, by default, both the
[fenced_code](extensions/fenced_code_blocks.md) and
[codehilite](extensions/code_hilite.md) extensions now prepend the prefix when
code highlighting is disabled.

If you have previously been including the prefix manually in your fenced code blocks, then you will not want a second
instance of the prefix. Similarly, if you are using a third party syntax highlighting tool which does not recognize
the prefix, or requires a different prefix, then you will want to redefine the prefix globally using the `lang_prefix`
configuration option of either the `fenced_code` or `codehilite` extensions.

For example, to configure `fenced_code` to not apply any prefix (the previous behavior), set the option to an empty string:

```python
from markdown.extensions.fenced_code import FencedCodeExtension

markdown.markdown(src, extensions=[FencedCodeExtension(lang_prefix='')])
```

!!! note
    When code highlighting is
    [enabled](extensions/fenced_code_blocks.md#enabling-syntax-highlighting),
    the output from Pygments is used unaltered. Currently, Pygments does not
    provide an option to include the language class in the output, let alone
    prefix it. Therefore, any language prefix is only applied when syntax
    highlighting is disabled.

#### Attribute Lists are more strict (#898).

Empty curly braces are now completely ignored by the [Attribute List](extensions/attr_list.md) extension. Previously, the extension would
recognize them as attribute lists and remove them from the document. Therefore, it is no longer necessary to backslash
escape a set of curly braces which are empty or only contain whitespace.

Despite not being documented, previously an attribute list could be defined anywhere within a table cell and get
applied to the cell (`<td>` element). Now the attribute list must be defined at the end of the cell content and must
be separated from the rest of the content by at least one space. This makes it easy to differentiate between attribute
lists defined on inline elements within a cell and the attribute list for the cell itself. It is also more consistent
with how attribute lists are defined on other types of elements.

The extension has also added support for defining attribute lists on table header cells (`<th>` elements) in the same
manner as data cells (`<td>` elements).

In addition, the documentation for the extensions received an overhaul. The features (#987) and limitations (#965) of the extension are now fully documented.

### Added

* All Pygments' options are now available for syntax highlighting (#816).
    - The [Codehilite](extensions/code_hilite.md) extension now accepts any options
      which Pygments supports as global configuration settings on the extension.
    - [Fenced Code Blocks](extensions/fenced_code_blocks.md) will accept any of the
      same options on individual code blocks.
    - Any of the previously supported aliases to Pygments' options continue to be
      supported at this time. However, it is recommended that the Pygments option names
      be used directly to ensure continued compatibility in the future.

* [Fenced Code Blocks](extensions/fenced_code_blocks.md) now work with
  [Attribute Lists](extensions/attr_list.md) when syntax highlighting is disabled.
  Any random HTML attribute can be defined and set on the `<code>` tag of fenced code
  blocks when the `attr_list` extension is enabled (#816).

* The HTML parser has been completely replaced. The new HTML parser is built on Python's
  [`html.parser.HTMLParser`](https://docs.python.org/3/library/html.parser.html), which
  alleviates various bugs and simplify maintenance of the code (#803, #830).

* The [Markdown in HTML](extensions/md_in_html.md) extension has been rebuilt on the
  new HTML Parser, which drastically simplifies it. Note that raw HTML elements with a
  `markdown` attribute defined are now converted to ElementTree Elements and are rendered
  by the serializer. Various bugs have been fixed (#803, #595, #780, and #1012).

* Link reference parsing, abbreviation reference parsing and footnote reference parsing
  has all been moved from `preprocessors` to `blockprocessors`, which allows them to be
  nested within other block level elements. Specifically, this change was necessary to
  maintain the current behavior in the rebuilt Markdown in HTML extension. A few random
  edge-case bugs (see the included tests) were resolved in the process (#803).

* An alternate function `markdown.extensions.headerid.slugify_unicode` has been included
  with the [Table of Contents](extensions/toc.md) extension which supports Unicode
  characters in table of contents slugs. The old `markdown.extensions.headerid.slugify`
  method which removes non-ASCII characters remains the default. Import and pass
  `markdown.extensions.headerid.slugify_unicode` to the `slugify` configuration option
  to use the new behavior.

* Support was added for Python 3.9 and dropped for Python 3.5.

### Fixed

* Document how to pass configuration options to Extra (#1019).
* Fix HR which follows strong em (#897).
* Support short reference image links (#894).
* Avoid a `RecursionError` from deeply nested blockquotes (#799).
* Fix issues with complex emphasis (#979).
* Fix unescaping of HTML characters `<>` in CodeHilite (#990).
* Fix complex scenarios involving lists and admonitions (#1004).
* Fix complex scenarios with nested ordered and unordered lists in a definition list (#918).

## [3.2.2] -- 2020-05-08

### Fixed

* Add `checklinks` tox environment to ensure all links in documentation are good.
* Refactor extension API documentation (#729).
* Load entry_points (for extensions) only once using `importlib.metadata`.
* Do not double escape entities in TOC.
* Correctly report if an extension raises a `TypeError` (#939).
* Raise a `KeyError` when attempting to delete a nonexistent key from the
  extension registry (#939).
* Remove import of `packaging` (or `pkg_resources` fallback) entirely.
* Remove `setuptools` as a run-time dependency (`install_required`).

## [3.2.1] -- 2020-02-12

### Fixed

* The `name` property in `toc_tokens` from the TOC extension now
  escapes HTML special characters (`<`, `>`, and `&`).

## [3.2] -- 2020-02-07

### Changed

#### Drop support for Python 2.7

Python 2.7 reaches end-of-life on 2020-01-01 and Python-Markdown 3.2 has dropped
support for it. Please upgrade to Python 3, or use Python-Markdown 3.1.

#### `em` and `strong` inline processor changes

In order to fix issue #792, `em`/`strong` inline processors were refactored. This
translated into removing many of the existing inline processors that handled this
logic:

* `em_strong`
* `strong`
* `emphasis`
* `strong2`
* `emphasis`

These processors were replaced with two new ones:

* `em_strong`
* `em_strong2`

The [`legacy_em`](extensions/legacy_em.md) extension was also modified with new,
refactored logic and simply overrides the `em_strong2` inline processor.

#### CodeHilite now always wraps with `<code>` tags

Before, the HTML generated by CodeHilite looked like:
- `<pre><code>foo = 'bar'</code></pre>` if you **were not** using Pygments.
- `<pre>foo = 'bar'</pre>`  if you **were** using Pygments.

To make the cases more consistent (and adhere to many Markdown specifications and
HTML code block markup suggestions), CodeHilite will now always additionally wrap
code with `<code>` tags. See #862 for more details.

This change does not alter the Python-Markdown API, but users relying on the old
markup will find their output now changed.

Internally, this change relies on the Pygments 2.4, so you must be using at least
that version to see this effect. Users with earlier Pygments versions will
continue to see the old behavior.

#### `markdown.util.etree` deprecated

Previously, Python-Markdown was using either the `xml.etree.cElementTree` module
or the `xml.etree.ElementTree` module, based on their availability. In modern
Python versions, the former is a deprecated alias for the latter. Thus, the
compatibility layer is deprecated and extensions are advised to use
`xml.etree.ElementTree` directly. Importing `markdown.util.etree` will raise
a `DeprecationWarning` beginning in version 3.2 and may be removed in a future
release.

Therefore, extension developers are encouraged to replace
`from markdown.util import etree` with
`import xml.etree.ElementTree as etree` in their code.

### Added

* Some new configuration options have been added to the [toc](extensions/toc.md)
  extension:

    * The `anchorlink_class` and `permalink_class` options allow class(es) to be
      assigned to the `anchorlink` and `permalink` respectively. This allows using
      icon fonts from CSS for the links. Therefore, an empty string passed to
      `permalink` now generates an empty `permalink`. Previously no `permalink`
      would have been generated. (#776)

    * The `permalink_title` option allows the title attribute of a `permalink` to be
      set to something other than the default English string `Permanent link`. (#877)

* Document thread safety (#812).

* Markdown parsing in HTML has been exposed via a separate extension called
  [`md_in_html`](extensions/md_in_html.md).

* Add support for Python 3.8.

### Fixed

* HTML tag placeholders are no longer included in  `.toc_tokens` (#899).
* Unescape backslash-escaped characters in TOC ids (#864).
* Refactor bold and italic logic in order to solve complex nesting issues (#792).
* Always wrap CodeHilite code in `code` tags (#862).

## [3.1.1] -- 2019-05-20

### Fixed

* Fixed import failure in `setup.py` when the source directory is not
  on `sys.path` (#823).
* Prefer public `packaging` module to pkg_resources' private copy of
  it (#825).

## [3.1] -- 2019-03-25

### Changed

#### `markdown.version` and `markdown.version_info` deprecated

Historically, version numbers were acquired via the attributes
`markdown.version` and `markdown.version_info`. As of 3.0, a more standardized
approach is being followed and versions are acquired via the
`markdown.__version__` and `markdown.__version_info__` attributes.  As of 3.1
the legacy attributes will raise a `DeprecationWarning` if they are accessed. In
a future release the legacy attributes will be removed.

### Added

* A [Contributing Guide](contributing.md) has been added (#732).

* A new configuration option to set the footnote separator has been added. Also,
  the `rel` and `rev` attributes have been removed from footnotes as they are
  not valid in HTML5. The `refs` and `backrefs` classes already exist and
  serve the same purpose (#723).

* A new option for `toc_depth` to set not only the bottom section level,
  but also the top section level. A string consisting of two digits
  separated by a hyphen in between (`"2-5"`), defines the top (`t`) and the
  bottom (`b`) (`<ht>..<hb>`). A single integer still defines the bottom
  section level (`<h1>..<hb>`) only. (#787).

### Fixed

* Update CLI to support PyYAML 5.1.
* Overlapping raw HTML matches no longer leave placeholders behind (#458).
* Emphasis patterns now recognize newline characters as whitespace (#783).
* Version format had been updated to be PEP 440 compliant (#736).
* Block level elements are defined per instance, not as class attributes
  (#731).
* Double escaping of block code has been eliminated (#725).
* Problems with newlines in references has been fixed (#742).
* Escaped `#` are now handled in header syntax (#762).

## [3.0.1] -- 2018-09-28

### Fixed

* Brought back the `version` and `version_info` variables (#709).
* Added support for hexadecimal HTML entities (#712).

## [3.0] -- 2018-09-21

### Changed

#### `enable_attributes` keyword deprecated

The `enable_attributes` keyword is deprecated in version 3.0 and will be
ignored. Previously the keyword was `True` by default and enabled an
undocumented way to define attributes on document elements. The feature has been
removed from version 3.0. As most users did not use the undocumented feature, it
should not affect most users. For the few who did use the feature, it can be
enabled by using the [Legacy Attributes](extensions/legacy_attrs.md)
extension.

#### `smart_emphasis` keyword and `smart_strong` extension deprecated

The `smart_emphasis` keyword is deprecated in version 3.0 and will be ignored.
Previously the keyword was `True` by default and caused the parser to ignore
middle-word emphasis. Additionally, the optional `smart_strong` extension
provided the same behavior for strong emphasis. Both of those features are now
part of the default behavior, and the [Legacy
Emphasis](extensions/legacy_em.md) extension is available to disable that
behavior.

#### `output_formats` simplified to `html` and `xhtml`.

The `output_formats` keyword now only accepts two options: `html` and `xhtml`
Note that if `(x)html1`, `(x)html4` or `(x)html5` are passed in, the number is
stripped and ignored.

#### `safe_mode` and `html_replacement_text` keywords deprecated

Both `safe_mode` and the associated `html_replacement_text` keywords are
deprecated in version 3.0 and will be ignored. The so-called "safe mode" was
never actually "safe" which has resulted in many people having a false sense of
security when using it. As an alternative, the developers of Python-Markdown
recommend that any untrusted content be passed through an HTML sanitizer (like
[Bleach](https://bleach.readthedocs.io/)) after being converted to HTML by
markdown. In fact, [Bleach
Whitelist](https://github.com/yourcelf/bleach-whitelist) provides a curated list
of tags, attributes, and styles suitable for filtering user-provided HTML using
bleach.

If your code previously looked like this:

```python
html = markdown.markdown(text, safe_mode=True)
```

Then it is recommended that you change your code to read something like this:

```python
import bleach
from bleach_whitelist import markdown_tags, markdown_attrs
html = bleach.clean(markdown.markdown(text), markdown_tags, markdown_attrs)
```

If you are not interested in sanitizing untrusted text, but simply desire to
escape raw HTML, then that can be accomplished through an extension which
removes HTML parsing:

```python
from markdown.extensions import Extension

class EscapeHtml(Extension):
    def extendMarkdown(self, md):
        md.preprocessors.deregister('html_block')
        md.inlinePatterns.deregister('html')

html = markdown.markdown(text, extensions=[EscapeHtml()])
```

As the HTML would not be parsed with the above Extension, then the serializer
will escape the raw HTML, which is exactly what happened in previous versions
with `safe_mode="escape"`.

#### Positional arguments deprecated

Positional arguments on the `markdown.Markdown()` class are deprecated as are
all except the `text` argument on the `markdown.markdown()` wrapper function.
Using positional arguments will raise an error. Only keyword arguments should be
used. For example, if your code previously looked like this:

```python
html = markdown.markdown(text, [SomeExtension()])
```

Then it is recommended that you change it to read something like this:

```python
html = markdown.markdown(text, extensions=[SomeExtension()])
```

!!! Note
    This change is being made as a result of deprecating `"safe_mode"` as the
    `safe_mode` argument was one of the positional arguments. When that argument
    is removed, the two arguments following it will no longer be at the correct
    position. It is recommended that you always use keywords when they are
    supported for this reason.

#### Extension name behavior has changed

In previous versions of Python-Markdown, the built-in extensions received
special status and did not require the full path to be provided. Additionally,
third party extensions whose name started with `"mdx_"` received the same
special treatment. This is no longer the case.

Support has been added for extensions to define an [entry
point](extensions/api.md#entry_point). An entry point is a string name which
can be used to point to an `Extension` class. The built-in extensions now have
entry points which match the old short names. And any third-party extensions
which define entry points can now get the same behavior. See the documentation
for each specific extension to find the assigned name.

If an extension does not define an entry point, then the full path to the
extension must be used. See the [documentation](reference.md#extensions) for
a full explanation of the current behavior.

#### Extension configuration as part of extension name deprecated

The previously documented method of appending the extension configuration
options as a string to the extension name is deprecated and will raise an error.
The [`extension_configs`](reference.md#extension_configs) keyword should be
used instead. See the [documentation](reference.md#extension_configs) for a
full explanation of the current behavior.

#### HeaderId extension deprecated

The HeaderId Extension is deprecated and will raise an error if specified. Use
the [Table of Contents](extensions/toc.md) Extension instead, which offers
most of the features of the HeaderId Extension and more (support for meta data
is missing).

Extension authors who have been using the `slugify` and `unique` functions
defined in the HeaderId Extension should note that those functions are now
defined in the Table of Contents extension and should adjust their import
statements accordingly (`from markdown.extensions.toc import slugify, unique`).

####  Homegrown `OrderedDict` has been replaced with a purpose-built `Registry`

All processors and patterns now get "registered" to a
[Registry](extensions/api.md#registry). A backwards compatible shim is
included so that existing simple extensions should continue to work.
A `DeprecationWarning` will be raised for any code which calls the old API.

#### Markdown class instance references.

Previously, instances of the `Markdown` class were represented as any one of
`md`, `md_instance`, or `markdown`. This inconsistency made it difficult when
developing extensions, or just maintaining the existing code. Now, all instances
are consistently represented as `md`.

The old attributes on class instances still exist, but raise a
`DeprecationWarning` when accessed. Also on classes where the instance was
optional, the attribute always exists now and is simply `None` if no instance
was provided (previously the attribute would not exist).

#### `markdown.util.isBlockLevel` deprecated

The `markdown.util.isBlockLevel` function is deprecated and will raise a
`DeprecationWarning`. Instead, extensions should use the `isBlockLevel` method
of the `Markdown` class instance. Additionally, a list of block level elements
is defined in the `block_level_elements` attribute of the `Markdown` class which
extensions can access to alter the list of elements which are treated as block
level elements.

#### `md_globals` keyword deprecated from extension API

Previously, the `extendMarkdown` method of a `markdown.extensions.Extension`
subclasses accepted an `md_globals` keyword, which contained the value returned
by Python's `globals()` built-in function. As all of the configuration is now
held within the `Markdown` class instance, access to the globals is no longer
necessary and any extensions which expect the keyword will raise a
`DeprecationWarning`. A future release will raise an error.

#### `markdown.version` and `markdown.version_info` deprecated

Historically, version numbers were acquired via the attributes
`markdown.version` and `markdown.version_info`. Moving forward, a more
standardized approach is being followed and versions are acquired via the
`markdown.__version__` and `markdown.__version_info__` attributes.  The legacy
attributes are still available to allow distinguishing versions between the
legacy Markdown 2.0 series and the Markdown 3.0 series, but in the future the
legacy attributes will be removed.

#### Added new, more flexible `InlineProcessor` class

A new `InlineProcessor` class handles inline processing much better and allows
for more flexibility. The new `InlineProcessor` classes no longer utilize
unnecessary pretext and post-text captures. New class can accept the buffer that
is being worked on and manually process the text without regular expressions and
return new replacement bounds. This helps us to handle links in a better way and
handle nested brackets and logic that is too much for regular expression.

### Added

* A new [testing framework](test_tools.md) is included as a part of the
  Markdown library, which can also be used by third party extensions.

* A new `toc_depth` parameter has been added to the
  [Table of Contents Extension](extensions/toc.md).

* A new `toc_tokens` attribute has been added to the Markdown class by the
  [Table of Contents Extension](extensions/toc.md), which contains the raw
  tokens used to build the Table of Contents. Users can use this to build their
  own custom Table of Contents rather than needing to parse the HTML available
  on the `toc` attribute of the Markdown class.

* When the [Table of Contents Extension](extensions/toc.md) is used in
  conjunction with the [Attribute Lists Extension](extensions/attr_list.md)
  and a `data-toc-label` attribute is defined on a header, the content of the
  `data-toc-label` attribute is now used as the content of the Table of Contents
  item for that header.

* Additional CSS class names can be appended to
  [Admonitions](extensions/admonition.md).

## Previous Releases

For information on prior releases, see their changelogs:

* [2.x and earlier](change_log/index.md)