Steven Matchett shares a LISP routine that will alter AutoCAD's UCS (user coordinate system) in order to simplify the creation of ordinate dimensions.
"I get tired of changing my UCS when I'm creating running dimensions, so I made this LISP routine for setting the zero point for ordinate (running) dimensions, then continuing the dimensions. The default command is RD. All you need to do is click the zero reference point, the base point for the dimension, and the other end of the dimension; the remainder of the dimensions will continue from the first."
Notes from Cadalyst Tip Reviewer Brian Benton: This routine simplifies the creation of ordinate dimensions quite well. Typically, out of the box, you have to place ordinate dimensions one at a time, and you have to select the same source point each time. This routine removes a few steps for you. It creates a new UCS based on your source point, then allows you to keep dimensioning from that point. Be sure to reset to World coordinates when you are finished.