Some embodiments provide a method of analyzing an unstructured document. The method receiving the unstructured document that includes a number of primitive graphic elements, each of which is defined as a single object in the unstructured document. The unstructured document has a drawing order that indicates the order in which the primitive graphic elements are drawn when the unstructured document is displayed. The method identifies positional relationships between successive primitive graphic elements in the drawing order. Based on the positional relationships, the method defines a single structural graphic element from several of the primitive graphic elements.