DuctiSoft President Andrea Andreetti is back this month with another great routine for AutoCAD. Tadd is a LISP routine that will display the total area, perimeter, and length of a selection set of objects. This can be helpful if you want to calculate the total area of multiple closed polylines, for example. Start by loading the LISP file, then type in the command Tadd. Nothing will appear to happen, but in the background a reactor has been loaded. Now when you select any number of object types — including polylines, splines, regions, arcs, and circles — a modeless dialog will appear and/or update showing you the result of the calculations. You can leave the dialog in place, close it, or move it at any time. The modeless dialog is generated using a function exposed by the AutoCAD Express Tools (ET); in the unlikely case that your ET is not installed or is otherwise not operational, this routine may not work. Thanks, Andrea.