This plugin installs a protocol handler for a protocol called CPROTO in <oXygen/>. That enables <oXygen/> to open resources with a URL of the form: cproto://C:/path/to/file.txt using the normal file system browser dialogs of <oXygen/>.

Such a plugin must provide a standard Java URL stream handler class (URLStreamHandlerPluginExtension) and must return a URL with the supported protocol when it is called by t;oXygen/> (URLChooserPluginExtension).

After installing the plugin it can be accessed from the File menu through action Open using Custom Protocol.

For more details: http://www.oxygenxml.com/doc/ug-oxygen/index.html?q=/doc/ug-oxygen/tasks/howto-custom-protocol-plugin.html