public Extent(Document doc)
        {
            Point3d point3d;
            Point3d point3d2;

            if (DocUtil.GetActiveExtents(doc, out point3d, out point3d2))
            {
                Point3d point3d3 = new Point3d(point3d.X, point3d.Y, 0.0);
                Point3d point3d4 = new Point3d(point3d2.X, point3d2.Y, 0.0);
                this.XMin = new double?(point3d3.X);
                this.YMin = new double?(point3d3.Y);
                this.XMax = new double?(point3d4.X);
                this.YMax = new double?(point3d4.Y);
                try
                {
                    this.SpatialReference = AfaDocData.ActiveDocData.DocPRJ.WKT;
                    return;
                }
                catch
                {
                    try
                    {
                        this.SpatialReference = MSCPrj.ReadWKT(doc);
                    }
                    catch
                    {
                        this.SpatialReference = "";
                    }
                    return;
                }
            }
            this.XMin             = (this.XMax = (this.YMin = (this.YMax = new double?(0.0))));
            this.SpatialReference = "";
        }