Some names are already reserved for viz to designate predefined
objects or entities. The following table lists all the names as well as
the messages that can apply to them.
| Object name | Description | Valid for message |
| world | Used as the top-level parent of the scene. | Use as parent for add. |
| _camera_# | Refers to camera of viewer #. | changePos, changeOrient. |
| _light_# | Refers to light of viewer # | Currently no message |
| _background_# | Refers to background of viewer #. Note that "_background" refers to all viewers background. | changeColor. |
| _test | Test object (Cube) (only in debug level > TRACE). | Any message. |
| _all | Refers to all object of scene | remove (cleanup 'world'). |