Autodesk.AutoCAD.Interop.Common.AcadAttributeReference acadAtt =
lstAtt[i].AcadObject as Autodesk.AutoCAD.Interop.Common.AcadAttributeReference;
object objMin; object objMax; double[] ptMin; double[] ptMax;
acadAtt.GetBoundingBox(out objMin, out objMax);
ptMin = (double[])objMin;
ptMax = (double[])objMax;
lstAtt[i].AcadObject as Autodesk.AutoCAD.Interop.Common.AcadAttributeReference;
object objMin; object objMax; double[] ptMin; double[] ptMax;
acadAtt.GetBoundingBox(out objMin, out objMax);
ptMin = (double[])objMin;
ptMax = (double[])objMax;