I am currently trying to create a SAP license key for our development system which is a Windows Server 2016.
On the form, I am requested to enter a 3 characters long system ID. I tried to find out what this means and where exactly can I find it on the server, but was not successful, mainly because it is required to be 3 characters long.

I would like to ask for help to find the 3 characters long system ID on Windows Server 2016.
Can anyone help please?