--- /dev/null
+.. _extend_salome:
+
+******************************
+Add/remove modules dynamically
+******************************
+
+.. contents:: Table of Contents
+
+"SALOME on demand" feature provides a possibility to dynamically add or remove
+SALOME modules directly from GUI.
+
+.. _hp_salomex_format:
+
+Description file
+================
+
+**"SALOME on demand"** feature introduces notion of a module description file.
+This is the file in JSON format that has `.salomex` extension. The description
+file provides some parameters of the module; two parameters are mandatory:
+name of the module and path to its root directory.
+
+Example:
+
+.. code-block:: json
+
+ {
+ "name": "PYHELLO",
+ "root": "/home/user/salome/modules/PYHELLO"
+ }
+
+.. note:: In the description file, the `name` parameter is an **internal** name of the module,
+ in contrast to its **title** which is described in `SalomeApp.xml` or `LightApp.xml`
+ resource file.
+
+.. note:: One `.salomex` file may describe one SALOME module only.
+
+.. _hp_modules_toolbar:
+
+Modules toolbar
+===============
+
+The *Modules* toolbar provides two additional buttons, which allow adding or removing
+modules directly from GUI.
+
+.. figure:: ../images/modules_toolbar.png
+ :align: center
+ :alt: Modules toolbar
+
+.. |add| image:: ../images/modules_add.png
+ :height: 24px
+
+.. |remove| image:: ../images/modules_remove.png
+ :height: 24px
+
+.. _hp_modules_add:
+
+Adding modules
+--------------
+
+Pressing the first button |add| shows a standard *Open File* dialog that allows
+selecting one or more `.salomex` files. Each module correctly configured in the
+corresponding `.salomex` file is then added to the SALOME session and appears in the
+*Modules* toolbar. As soon as it is done, the user may work with the module in the same
+way as with any other module: all features are available after activating module from
+*Modules* toolbar.
+
+The modules added in this way become *persistent*. This means that after restarting
+SALOME these modules are available in the *Modules* toolbar.
+
+.. _hp_modules_remove:
+
+Removing modules
+----------------
+
+Pressing a small arrow near the second button |remove| shows a drop-down menu with
+the list of manually added modules, where the user may select a module to remove. As soon
+as user selects a module to remove, a message box is shown asking the user if it is
+necessary also to remove a directory, containing the module, from disk. If user
+confirms removal of the directory, it will be necessary to save the study, in order to
+avoid possible data loss.
+
+.. note:: The module libraries are not removed from RAM until exit from the current
+ SALOME session, so some its functionality may be still accessible, for example,
+ via Python API. However, using module functionality may have unpredicted
+ behavior.
