This LISP file contains three separate functions that the tip author, Dave Couch, uses for dimensioning residential and commercial site plans in AutoCAD — although the uses for these routines do not stop there. Start by loading the LISP routine; the three functions are DimNearToPerp, DimEndToPerp, and DimEndToEnd. The first will create a dimension from a picked (near) point to a perpendicular picked point. The second one creates a dimension from an endpoint to a perpendicular picked point, and the last one creates a dimension between two endpoints. In each case the correct object snap settings are set for you by the routine, without disturbing your current running object snap settings.