dropInternal() is used within the ON DROP block to allow dragging and dropping within one and the same object to perform all the necessary changes within the array rows and move the row selection together with the corresponding cell attributes.
Drag-and-drop events performed in tree views require much coding to manipulate parent-child relations: the dropped node can be inserted under parent to different levels of hierarchy and in different places among the siblings. However, you can also use dropInternal() with regular tables.
dropInterna() will be ignored without any error messages, if the element is dragged from one object and dropped to another one as well as in case it is called outside the ON DROP block.