The following is taken from the DPS document pysource-reader.txt::

  Interpreted Text
  ================

  DTD elements: package, module, class, method, function,
  module_attribute, class_attribute, instance_attribute, variable,
  parameter, type, exception_class, warning_class.

  In Python docstrings, interpreted text is used to classify and mark up
  program identifiers, such as the names of variables, functions,
  classes, and modules.  If the identifier alone is given, its role is
  inferred implicitly according to the Python namespace lookup rules.
  For functions and methods (even when dynamically assigned),
  parentheses ('()') may be included::

      This function uses `another()` to do its work.

  For class, instance and module attributes, dotted identifiers are used
  when necessary::

      class Keeper(Storer):

          """
          Extend `Storer`.  Class attribute `instances` keeps track of
          the number of `Keeper` objects instantiated.
          """

          instances = 0
          """How many `Keeper` objects are there?"""

          def __init__(self):
              """
              Extend `Storer.__init__()` to keep track of instances.

              Keep count in `self.instances` and data in `self.data`.
              """
              Storer.__init__(self)
              self.instances += 1

              self.data = []
              """Store data in a list, most recent last."""

          def storedata(self, data):
              """
              Extend `Storer.storedata()`; append new `data` to a list
              (in `self.data`).
              """
              self.data = data

  To classify identifiers explicitly, the role is given along with the
  identifier in either prefix or suffix form::

      Use :method:`Keeper.storedata` to store the object's data in
      `Keeper.data`:instance_attribute:.

  The role may be one of 'package', 'module', 'class', 'method',
  'function', 'module_attribute', 'class_attribute',
  'instance_attribute', 'variable', 'parameter', 'type',
  'exception_class', 'exception', 'warning_class', or 'warning'.  Other
  roles may be defined.