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+Docutils markup API
+===================
+
+This section describes the API for adding ReST markup elements (roles and
+directives).
+
+Roles
+-----
+
+
+Directives
+----------
+
+Directives are handled by classes derived from
+``docutils.parsers.rst.Directive``.  They have to be registered by an extension
+using :meth:`.Sphinx.add_directive` or :meth:`.Sphinx.add_directive_to_domain`.
+
+.. module:: docutils.parsers.rst
+
+.. class:: Directive
+
+   The markup syntax of the new directive is determined by the follow five class
+   attributes:
+
+   .. autoattribute:: required_arguments
+   .. autoattribute:: optional_arguments
+   .. autoattribute:: final_argument_whitespace
+   .. autoattribute:: option_spec
+
+      Option validator functions take a single parameter, the option argument
+      (or ``None`` if not given), and should validate it or convert it to the
+      proper form.  They raise :exc:`ValueError` or :exc:`TypeError` to indicate
+      failure.
+
+      There are several predefined and possibly useful validators in the
+      :mod:`docutils.parsers.rst.directives` module.
+
+   .. autoattribute:: has_content
+
+   New directives must implement the :meth:`run` method:
+
+   .. method:: run()
+
+      This method must process the directive arguments, options and content, and
+      return a list of Docutils/Sphinx nodes that will be inserted into the
+      document tree at the point where the directive was encountered.
+
+   Instance attributes that are always set on the directive are:
+
+   .. attribute:: name
+
+      The directive name (useful when registering the same directive class under
+      multiple names).
+
+   .. attribute:: arguments
+
+      The arguments given to the directive, as a list.
+
+   .. attribute:: options
+
+      The options given to the directive, as a dictionary mapping option names
+      to validated/converted values.
+
+   .. attribute:: content
+
+      The directive content, if given, as a :class:`!ViewList`.
+
+   .. attribute:: lineno
+
+      The absolute line number on which the directive appeared.  This is not
+      always a useful value; use :attr:`srcline` instead.
+
+   .. attribute:: content_offset
+
+      Internal offset of the directive content.  Used when calling
+      ``nested_parse`` (see below).
+
+   .. attribute:: block_text
+
+      The string containing the entire directive.
+
+   .. attribute:: state
+                  state_machine
+
+      The state and state machine which controls the parsing.  Used for
+      ``nested_parse``.
+
+
+ViewLists
+^^^^^^^^^
+
+Docutils represents document source lines in a class
+``docutils.statemachine.ViewList``.  This is a list with extended functionality
+-- for one, slicing creates views of the original list, and also the list
+contains information about the source line numbers.
+
+The :attr:`Directive.content` attribute is a ViewList.  If you generate content
+to be parsed as ReST, you have to create a ViewList yourself.  Important for
+content generation are the following points:
+
+* The constructor takes a list of strings (lines) and a source (document) name.
+
+* The ``.append()`` method takes a line and a source name as well.
+
+
+Parsing directive content as ReST
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Many directives will contain more markup that must be parsed.  To do this, use
+one of the following APIs from the :meth:`Directive.run` method:
+
+* ``self.state.nested_parse``
+* :func:`sphinx.util.nodes.nested_parse_with_titles` -- this allows titles in
+  the parsed content.
+
+Both APIs parse the content into a given node. They are used like this::
+
+   node = docutils.nodes.paragraph()
+   # either
+   nested_parse_with_titles(self.state, self.result, node)
+   # or
+   self.state.nested_parse(self.result, 0, node)
+
+.. note::
+
+   ``sphinx.util.docutils.switch_source_input()`` allows to change a target file
+   during nested_parse.  It is useful to mixed contents.  For example, ``sphinx.
+   ext.autodoc`` uses it to parse docstrings::
+
+       from sphinx.util.docutils import switch_source_input
+
+       # Switch source_input between parsing content.
+       # Inside this context, all parsing errors and warnings are reported as
+       # happened in new source_input (in this case, ``self.result``).
+       with switch_source_input(self.state, self.result):
+           node = docutils.nodes.paragraph()
+           self.state.nested_parse(self.result, 0, node)
+
+   .. deprecated:: 1.7
+
+      Until Sphinx 1.6, ``sphinx.ext.autodoc.AutodocReporter`` was used for this
+      purpose.  It is replaced by ``switch_source_input()``.
+
+If you don't need the wrapping node, you can use any concrete node type and
+return ``node.children`` from the Directive.
+
+
+.. seealso::
+
+   `Creating directives`_ HOWTO of the Docutils documentation
+
+.. _Creating directives: https://docutils.sourceforge.io/docs/howto/rst-directives.html