This extension is used to define correlations between types of users and permissions. If you send request packet containing the **get-permission-descriptor** operation, the respond from the server will contain permission level in the **level** node nested into the **extension** node. The graphical representation of the construction is as follows:
image 40021.gif
This node can be empty, or contain one of the following values: - *client*. The parameter is visible to customers. - *domain*. The parameter is visible to webspace users. - *mail*. The parameter is visible to mail account users.
Note You can specify multiple **service** parameters in one **extension** node.
**Extension node sample**
<packet>
<property>
            <name>manage_virusfilter</name>
            <type>boolean</type>
            <default-value>false</default-value>
            <writable-by>admin</writable-by>
            <label>cl_perm__manage_virusfilter</label>
            <extension>
              <level>client</level>
              <level>domain</level>
              <level>mail</level>
            </extension>
</property>
For details on permissions, refer to the sections **Supported Operations: Managing Customer Accounts \> Limits and Permissions** , or Supported Operations: Managing Subscriptions (Webspaces) > Subscription Settings > Limits, Permissions and Hosting Settings.