dashboard 'test' warning

Alright guys,
im about to take the plunge and purchase a 1986 m3, but when you start the car up 'test' flashes on the dashboard.
The seller shrugged this off and cancelled it by pressing a button on the headlining.

Whats this warning mean? Has the car got problems??

Anyother useful tips for a first time m3 buyer?

Much appreciated!