7. The method of claim 5 , wherein the tree structure comprises anyone or any combination of following levels of node objects in sequence: a docbase, a document set, a document, a page, a layer, an object stream and a layout object.
7. The method of claim 5 , wherein the tree structure comprises anyone or any combination of following levels of node objects in sequence: a docbase, a document set, a document, a page, a layer, an object stream and a layout object. 11. The method of claim 7 , wherein the at least one privilege supported by the node object corresponding to the document data object further comprises: a privilege supported by a sub-node object of the node object, or a privilege supported by a parent node object of the node object.