0 if not
x = isvalid(vrnode_object_vector)
Name of an array of
This method returns an array that contains
the elements of
vrnode_object_vector are valid
0 when they are not.
vrnode object is considered valid if
the following conditions are met:
The parent world of the node exists.
The parent world of the node is open.
The VRML node with the given
exists in the parent world.