In GN4, all the scripts (linked to menus / shortcuts, and auxiliary scripts), are stored in one place - in GN4 add-ins.
Tera staff, System Administrators and Super Users manage add-ins methods and properties, ie. add new methods and properties, modify existing ones, assign methods to menus and shortcuts etc.
Tera staff manages system add-ins of the standard configuration.
System Administrators, Super Users manage custom add-ins. Custom add-ins are used also for regional scripts, e.g. US or Italian specific scripts are in site add-ins.
GN4 Visual Basic scripts are edited in the Microsoft Visual Studio Express Edition that is a freeware you can download and install on your work station. You use Visual Studio Express to compile add-ins after making changes.
Tera provides a Visual Studio Express solution that automates loading and compiling of add-ins.