Hi Wayne
It should be the Standard ID of the user. The way it works, as far as I understand it, is as follows:
When first upgrading to 8.4, you can log in using one of these two methods:
Standard ID and Standard ID password
User code (Person or Global User) and password stored against the user
When you log in with your Standard ID and password, and it is verified against HansaWorld's password server, it then writes this password back to the database, overwriting the password stored against the user. From this point on, you can log in with the Standard ID and password, or user code and Standard ID password. It is no longer possible to change the password of a user in the system.
If you are on a local network and the internet drops out, logging in with Standard ID fails, you have to log in with your user code.
I hope that helps and I hope it's accurate information.
Paul