Embedded into the functionality of the viewport command is a list of standard viewport scales. These preconfigured scales allow a user to set the scale of a viewport in a matter of seconds. While the included scales save a lot of time for a fair number of the industry's most common scales, it does not include every scale ever encountered. Likewise, there are likely a number of preconfigured scales that you never use.
The SCALELISTEDIT command gives the user control over which scales are included in this list. Using the SCALELISTEDIT command the user has the ability to add, delete, modify, and even reorder the standard scales provided in this list. If you are constantly using architectural units, why have engineering listed. Likewise if you are in engineering, why have all of the architectural scales listed?
Do note that the SCALELISTEDIT command is applied to AutoCAD as a program, and is not stored within the drawing. For this reason it is not possible to embed custom scales into drawing templates. Such functionality would of course be helpful for multi-discipline firms. If prefixed with a hyphen, the â€“SCALELISTEDIT command will display a command line only version of the command. This could prove helpful if one wanted to specify available scales using something such as a script or LISP â€“ loaded at startup.