The upnp:class tells the UPnP complaint device that this entity is a container, basically a folder, that contains additional entities, be they other containers or media items that the device can render. Again if you require lots more details see the UPnP documentation.  In UMSP plugin development we normally only deal with the following flavors of upnp:class
 
The upnp:class tells the UPnP complaint device that this entity is a container, basically a folder, that contains additional entities, be they other containers or media items that the device can render. Again if you require lots more details see the UPnP documentation.  In UMSP plugin development we normally only deal with the following flavors of upnp:class
   Exception encountered, of type "Error"