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+.. SPDX-License-Identifier: CC-BY-SA-4.0
+
+.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
+
+Directives
+==========
+
+This section details the user extension manager's directives.  A subsection is
+dedicated to each of this manager's directives and describes the calling
+sequence, related constants, usage, and status codes.
+
+.. raw:: latex
+
+   \clearpage
+
+.. index:: create an extension set
+.. index:: rtems_extension_create
+
+.. _rtems_extension_create:
+
+EXTENSION_CREATE - Create a extension set
+-----------------------------------------
+
+CALLING SEQUENCE:
+    .. code-block:: c
+
+        rtems_status_code rtems_extension_create(
+          rtems_name                    name,
+          const rtems_extensions_table *table,
+          rtems_id                     *id
+        );
+
+DIRECTIVE STATUS CODES:
+    .. list-table::
+     :class: rtems-table
+
+     * - ``RTEMS_SUCCESSFUL``
+       - extension set created successfully
+     * - ``RTEMS_INVALID_ADDRESS``
+       - ``table`` or ``id`` are NULL
+     * - ``RTEMS_INVALID_NAME``
+       - invalid extension set name
+     * - ``RTEMS_TOO_MANY``
+       - too many extension sets created
+
+DESCRIPTION:
+
+    This directive creates an extension set object and initializes it using the
+    specified extension set table.  The assigned extension set identifier is
+    returned in :c:data:`id`.  This identifier is used to access the extension
+    set with other user extension manager directives.  For control and
+    maintenance of the extension set, RTEMS allocates an Extension Set Control
+    Block (ESCB) from the local ESCB free pool and initializes it.  The
+    user-specified :c:data:`name` is assigned to the ESCB and may be used to
+    identify the extension set via
+    :ref:`rtems_extension_ident() <rtems_extension_ident>`.  The extension set
+    specified by :c:data:`table` is copied to the ESCB.
+
+NOTES:
+    This directive may cause the calling task to be preempted due to an
+    obtain and release of the object allocator mutex.
+
+.. raw:: latex
+
+   \clearpage
+
+.. index:: get ID of an extension set
+.. index:: obtain ID of an extension set
+.. index:: rtems_extension_ident
+
+.. _rtems_extension_ident:
+
+EXTENSION_IDENT - Get ID of a extension set
+-------------------------------------------
+
+CALLING SEQUENCE:
+    .. code-block:: c
+
+        rtems_status_code rtems_extension_ident(
+          rtems_name  name,
+          rtems_id   *id
+        );
+
+DIRECTIVE STATUS CODES:
+    .. list-table::
+     :class: rtems-table
+
+     * - ``RTEMS_SUCCESSFUL``
+       - extension set identified successfully
+     * - ``RTEMS_INVALID_NAME``
+       - extension set name not found
+
+DESCRIPTION:
+    This directive obtains the extension set identifier associated with the
+    extension set :c:data:`name` to be acquired and returns it in :c:data:`id`.
+    If the extension set name is not unique, then the extension set identifier
+    will match one of the extension sets with that name.  However, this
+    extension set identifier is not guaranteed to correspond to the desired
+    extension set.  The extension set identifier is used to access this
+    extension set in other extension set related directives.
+
+NOTES:
+    This directive will not cause the running task to be preempted.
+
+.. raw:: latex
+
+   \clearpage
+
+.. index:: delete an extension set
+.. index:: rtems_extension_delete
+
+.. _rtems_extension_delete:
+
+EXTENSION_DELETE - Delete a extension set
+-----------------------------------------
+
+CALLING SEQUENCE:
+    .. code-block:: c
+
+        rtems_status_code rtems_extension_delete(
+            rtems_id id
+        );
+
+DIRECTIVE STATUS CODES:
+    .. list-table::
+     :class: rtems-table
+
+     * - ``RTEMS_SUCCESSFUL``
+       - extension set deleted successfully
+     * - ``RTEMS_INVALID_ID``
+       - invalid extension set id
+
+DESCRIPTION:
+    This directive deletes the extension set specified by :c:data:`id`.  If the
+    extension set is running, it is automatically canceled.  The ESCB for the
+    deleted extension set is reclaimed by RTEMS.
+
+NOTES:
+    This directive may cause the calling task to be preempted due to an
+    obtain and release of the object allocator mutex.
+
+    A extension set can be deleted by a task other than the task which created
+    the extension set.