You can find another advanced bit of programming in ISO Dimensioning Tool (Tip #2112) by Jeffery P. Sanders. As frequent contributor Jeffrey puts it, "I guess everyone has to try to create their own version once." Isometric dimensioning is something that seems easy until you start to dig into the details and run into exceptions as well as intuitive concepts that vary from operator to operator. This utility runs in a manner like the regular AutoCAD dimensioning commands, so there is no need to explain the details. However, if you really want to exploit this marvelous utility, then you need to dig into the LISP code itself. Fortunately for those of us who like digging into the code, Jeffrey is a talented programmer who includes meaningful programmer comments in his creations.