The placement interface is an interface for non-leaf nodes with simple children inserting and removing. It has public methods for children manipulating.
Every object implementing the placement interface must also implement the object interface, the node interface, the container interface and the composite interface.
Children manipulating methods
This functions should be clear, so just one remark: a removed child is released (so it becomes a parent-free node) but not destroyed.
vcl_placement_add_child_on_top (void * obj, void * child)
vcl_placement_remove_child (void * obj, void * child)