<https://www.openbom.com/blog/openbom-add-in-for-autodesk-inventor-drawing-pdf-dxf-support#primaryimage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.openbom.com/blog/openbom-add-in-for-autodesk-inventor-drawing-pdf-dxf-support>