Item 

Description 

System variables  

Lists all environment variables and their values defined at a system level. You cannot delete an existing system variable, but you can override it.  

Add Override  

Displays the Override System Variable dialog box, allowing you to modify an existing system variable to create a new user override. This button is dimmed until you select a variable in the System variables list.  

User overrides  

Lists all defined user overrides and their values. A user override takes precedence over an existing system variable until you delete the user override.  

New  

Displays the New User Variable dialog box allowing you to create new user override to a system variable.  

Edit  

Displays the Edit User Variable dialog box allowing you to change the user override currently selected in the User overrides list.  

Delete  

Deletes the user override currently selected in the User overrides list.