3ds Max provides a container manager object, represented by the class IContainerManager for working with containers. A pointer to the container manager object can be retrieved using the GetContainerManagerInterface() global function.

Individual containers are exposed by 3ds Max using the IContainerObject interface. A container is represented in the scene as a box, and has an INode dedicated to it. This allows the user to select a container.

The container manager object can be used to retrieve an IContainerObject associated with an INode as follows:

bool IsContainer(INode* node) {
  IContainerObject* co = GetContainerManagerInterface()->IsContainerNode( node);
  return co != NULL;
}