The command is -DWGUNITS and not INSUNITS or LUNITS.
Please pay more attention before responding.
-DWGUNITS is a command.
INSUNITS and
LUNITS are system variables
As others have pointed out, -DWGUNITS looks to be related to an AutoCAD Vertical. It's not documented anywhere that I could find in the HELP. Also, from other posts it seems geared more towards converting a drawing from one set of units to another. Further to this, the prompting of the command changes depending on whether you've run the command previously in a drawing. So simply calling
(command "._-DWGUNITS" 6 2 3 "_N" "_Y")
may not work in all cases.
If you're simply trying to set the drawing units, then it would be better to explore the
-UNITS command.
How to do it without COMMAND to look elegant within a program?
All the settings of the -UNITS command can be set via a system variable, which allows you to avoid making a command call from lisp. This is a more elegant approach. e.g