Called by secret Agents to register their ability to provide and save network secrets. Identifies this agent; only one agent in each user session may use the same identifier. Identifier formatting follows the same rules as D-Bus bus names with the exception that the ':' character is not allowed. The valid set of characters is "[A-Z][a-z][0-9]_-." and the identifier is limited in length to 255 characters with a minimum of 3 characters. An example valid identifier is 'org.gnome.nm-applet' (without quotes). Called by secret Agents to notify NetworkManager that they will no longer handle requests for network secrets. Agents are automatically unregistered when they disconnect from D-Bus.