CellRefImpl srcRef = null;
boolean isOld = false;
final String srcSheetName = ec.getSheetName();
final int srcRow = ec.getRowIndex();
final int srcCol = ec.getColumnIndex();
final RefBook srcRefBook = BookHelper.getOrCreateRefBook(_book);
final RefSheet srcRefSheet = srcRefBook.getOrCreateRefSheet(srcSheetName);
if (ctx != null) {
final String srcRefKey = srcRefBook.getBookName()+"]"+srcSheetName+"!"+new CellReference(srcRow, srcCol).formatAsString();
final Object[] refs = (Object[]) ctx.getAttribute(srcRefKey);
if (refs != null) {
srcRef = (CellRefImpl) refs[0];
isOld = ((Boolean)refs[1]).booleanValue();
} else {