The short answer
Key numbers sit in column 12 of the card licence and either restrict a class or extend it. The 78 restricts you to vehicles with automatic transmission. The 197 expressly does not: it records an automatic test with an additional manual assessment and leaves the entitlement complete.
On the back of the card licence there is a column of numbers beside each class. Most are harmless — 01 means corrective lenses, 79 concerns technical design limits. Two of them decide your daily life with class B.
78 — automatic only
“Restricted to vehicles with automatic transmission.” Anyone with this number on their licence may not drive a manual — not briefly, not in a car park. Doing so counts as driving without a licence, with everything that follows: a criminal offence, and no insurance cover.
The 78 applies across Europe. It only appears against the classes it was acquired for — somebody who later takes a motorcycle licence does not automatically carry it over.
197 — tested on automatic, manual allowed
It stands for: practical test taken in an automatic, manual competence separately evidenced. It restricts nothing. Anyone holding a 197 drives manual and automatic without limitation.
Abroad
The 197 is a German rule. Roadside checks abroad do not know it and do not look for it — what matters there is that no 78 is entered. And with the 197, it is precisely not entered.
How to see what yours says
Back of the card, the table with the classes. Far right, column 12, are the key numbers for that row. A 78 next to B means you are restricted to automatics. Nothing there, or a 197, means you may drive both.
If you want to get rid of a 78, it takes no second practical test: ten driving lessons in a manual, a 15-minute test drive, and with the school's certificate the Straßenverkehrsamt strikes out the 78 and enters the 197. Only a 78 that sits on the licence on medical grounds still requires a practical test. We do that with you — ask us via contact. Anyone still at the start is better off deciding beforehand: B197 or B78.