Like many useful routines, this one is quite simple--deceptively so. If you work in 3d you'll find these routines invaluable. Similar to moving with point filters, these commands will move or copy objects along one axis only, no matter what reference osnaps are used.

1. Download "MoveCopy1Axis.lsp", or the Zip File if you prefer.
2. Save the file locally, and load it into your "acad.doc" file or Startup Suite (See "Loading Custom Lisp Routines" for detailed instructions).
3. Use the default "mx", "my", "mz", "cx", "cy", "cz" commands or map your own versions by editing the .lsp file or your .pgp file.
4. There are also "mxy" and "cxy" for moving objects in the World XY plane (along 2 axes actually) without altering their Z coordinates.