bpo-41192: Clarify the sys module's description of the auditing feature

Doc/library/sys.rst

@@ -31,16 +31,22 @@ always available.
    When an auditing event is raised through the :func:`sys.audit` function, each
    hook will be called in the order it was added with the event name and the
    tuple of arguments. Native hooks added by :c:func:`PySys_AddAuditHook` are
-   called first, followed by hooks added in the current interpreter.
+   called first, followed by hooks added in the current interpreter.  Hooks
+   can then log the event, raise an exception to abort the operation,
+   or terminate the process entirely.
 
    .. audit-event:: sys.addaudithook "" sys.addaudithook
 
-      Raise an auditing event ``sys.addaudithook`` with no arguments. If any
+      Calling :func:`sys.addaudithook` will itself raise an auditing event
+      named ``sys.addaudithook`` with no arguments. If any
       existing hooks raise an exception derived from :class:`RuntimeError`, the
       new hook will not be added and the exception suppressed. As a result,
       callers cannot assume that their hook has been added unless they control
       all existing hooks.
 
+   See the :ref:`audit events table <audit-events>` for all events raised by
+   CPython, and :pep:`578` for the original design discussion.
+
    .. versionadded:: 3.8
 
    .. versionchanged:: 3.8.1
@@ -81,14 +87,23 @@ always available.
 
    .. index:: single: auditing
 
-   Raise an auditing event with any active hooks. The event name is a string
-   identifying the event and its associated schema, which is the number and
-   types of arguments. The schema for a given event is considered public and
-   stable API and should not be modified between releases.
-
-   This function will raise the first exception raised by any hook. In general,
-   these errors should not be handled and should terminate the process as
-   quickly as possible.
+   Raise an auditing event and trigger any active auditing hooks.
+   *event* is a string identifying the event, and *args* may contain
+   optional arguments with more information about the event.  The
+   number and types of arguments for a given event are considered a
+   public and stable API and should not be modified between releases.
+
+   For example, one auditing event is named ``os.chdir``. This event has
+   one argument called *path* that will contain the requested new
+   working directory.
+
+   :func:`sys.audit` will call the existing auditing hooks, passing
+   the event name and arguments, and will re-raise the first exception
+   from any hook. In general, if an exception is raised, it should not
+   be handled and the process should be terminated as quickly as
+   possible. This allows hook implementations to decide how to respond
+   to particular events: they can merely log the event or abort the
+   operation by raising an exception.
 
    Hooks are added using the :func:`sys.addaudithook` or
    :c:func:`PySys_AddAuditHook` functions.