This extension defines a feature, LV2_Extension_Data_Feature, which provides access to LV2_Descriptor::extension_data() for plugin UIs or other potentially remote users of a plugin.
Note that the use of this extension by UIs violates the important principle of UI/plugin separation, and is potentially a source of many problems. Accordingly, use of this extension is highly discouraged, and plugins should not expect hosts to support it, since it is often impossible to do so.
To support this feature the host must pass an LV2_Feature struct to LV2_Descriptor::extension_data() with URI LV2_DATA_ACCESS_URI and data pointed to an instance of LV2_Extension_Data_Feature.