Many beginner tutorials for CAD have mentioned “system variables”, but is a system variable?

“system variable” is not CAD-specific term, it originated from mathematics. Simply speaking, it’s a parameter and abstract concept that stores the calculating results in computer languages. The system variables are used to save the environment setups for operations, geometry information and other command settings or values.

The function of system variable

CAD uses a system variable to display the current status and controls certain functions and how commands work. As we can see in the Options and Drafting Settings dialog boxes, many parameters have system variables, as shown in the following picture,

Some system variables are read-only and users can only check read-only variables instead of changing them. For example, the DWGNAME and SCREENSIZE, enter the system variable name, press Enter, we see the following:

For system variables without read-only restriction, users can enter the system variable name in the command line or user SETVAR command to change the system variable value.

The concept of system variables may be too abstract to understand, just use CAD as much as you can and we will get to know more about system variables over time.