diff --git a/Resources/doc/faq.rst b/Resources/doc/faq.rst
index b5f5950..aca9834 100644
--- a/Resources/doc/faq.rst
+++ b/Resources/doc/faq.rst
@@ -1,10 +1,129 @@
 Frequently Asked Questions (FAQ)
 ================================
 
-* Q: How do I fix 404 or 406 HTTP status on NelmioApiDocBundle assets files (css, js, images)?
+Sharing parameter configuration
+-------------------------------
 
-  A: Just execute this command to solve it:
+Q: I use the same value in multiple end points. How can I avoid duplicating the descriptions?
 
-  .. code-block:: bash
+A: You can configure ``definitions`` in the nelmio_api_doc configuration and then reference them:
+
+.. code-block:: yaml
+
+    # config/nelmio_api_doc.yml
+    nelmio_api_doc:
+        documentation:
+            definitions:
+                NelmioImageList:
+                    description: "Response for some queries"
+                    type: object
+                    properties:
+                        total:
+                            type: integer
+                            example: 42
+                        items:
+                            type: array
+                            items:
+                                $ref: "#/definitions/ImageMetadata"
+
+.. code-block:: php
+
+    // src/App/Controller/NelmioController.php
+
+    /**
+     * @SWG\Response(
+     *     response=200,
+     *     description="List of image definitions",
+     *     @SWG\Schema(
+     *       type="object",
+     *       title="ListOperationsResponse",
+     *       additionalProperties={"$ref": "#/definitions/NelmioImageList"}
+     *     )
+     */
+
+Optional Path Parameters
+------------------------
+
+Q: I have a controller with an optional path parameter. In swagger-ui, the parameter is required - can I make it
+   optional? The controller might look like this::
+
+    /**
+     * Get all user meta or metadata for a specific field.
+     *
+     * @Route("/{user}/meta/{metaName}",
+     *     methods={"GET"},
+     *     name="get_user_metadata"
+     * )
+     *
+     * @SWG\Response(
+     *     response=200,
+     *     description="Json object with all user meta data or a json string with the value of the requested field"
+     * )
+     */
+    public function getAction(string $user, string $metaName = null)
+    {
+        ...
+    }
+
+A: Optional path parameters are not supported by the OpenAPI specification. The solution to this is to define two
+   separate actions in your controller. For example::
+
+    /**
+     * Get all user meta data.
+     *
+     * @Route("/{user}/meta",
+     *     methods={"GET"},
+     *     name="get_user_metadata"
+     * )
+     *
+     * @SWG\Response(
+     *     response=200,
+     *     description="Json hashmap with all user meta data",
+     *     @SWG\Schema(
+     *        type="object",
+     *        example={"foo": "bar", "hello": "world"}
+     *     )
+     *
+     * )
+     */
+    public function cgetAction(string $user)
+    {
+        return $this->getAction($user, null);
+    }
+
+    /**
+     * Get user meta for a specific field.
+     *
+     * @Route("/{user}/meta/{metaName}",
+     *     methods={"GET"},
+     *     name="get_user_metadata_single"
+     * )
+     *
+     * @SWG\Response(
+     *     response=200,
+     *     description="A json string with the value of the requested field",
+     *     @SWG\Schema(
+     *          type="string"
+     *     )
+     * )
+     */
+    public function getAction(string $user, string $metaName = null)
+    {
+        ...
+    }
+
+The first action is redundant for Symfony, but adds all the relevant documentation for the OpenAPI specification.
+
+Asset files not loaded
+----------------------
+
+Q: How do I fix 404 or 406 HTTP status on NelmioApiDocBundle assets files (css, js, images)?
+
+A: The assets normally are installed by composer if any command event (usually ``post-install-cmd`` or
+   ``post-update-cmd``) triggers the ``ScriptHandler::installAssets`` script.
+   If you have not set up this script, you can manually execute this command:
+
+.. code-block:: bash
+
+    $ bin/console assets:install --symlink
 
-      $ bin/console assets:install --symlink