if (charts.size()>0) {
// for each chart, create a chart.xml + trap references for drawingX.xml.rels
for (int i= 0; i < charts.size(); i++) {
try { // obtain image OOXML + write image file to ZIP
Chart c= (Chart) charts.get(i);
drawing.append(getChartDrawingOOXML(new ChartHandle(c, bk)));
drawing.append("\r\n");
if (c instanceof OOXMLChart) {
ArrayList chartEmbeds= ((OOXMLChart)charts.get(i)).getChartEmbeds();
if (chartEmbeds!=null) {
int origDrawingId= drawingId; // id for THIS CURRENT DRAWING ML describing this chart(s), etc.