DrawingML is the ML for graphics data in Office Open XML.
oox::drawingml::Shape is the main data structure for the DrawingML. It will contain many XShape all created from the drawingml.
The class Shape, every hard shape attribute is stored there. The text will be stored in the shape.
The class "TextListStyle" is storing style information "TextParagraphProperties" for each of the ten text paragraphs (also a aggregation list style that is used for sub titles)
The "TextParagraphProperties" class is storing paragraph and character properties.
SmartArt is the "diagramming" part of DrawingML. OpenOffice.org do not have an equivalent feature so the import will have to include the logic of SmartArt to generate Shapes from the whole diagram description.
Diagrams are in their own fragments and in it their own XML namespace.