Zundfolge,
Correct. The easiest way to tell these 3 "generations" apart is the following:
1. Marked S9 on slide, may or may not have manual safety. Old style grip.
2. Marked S9-A1, new grip, no roll pin under rear sight
3. Marked S9-A1, new grip, roll pin under rear sight.
Gen 1 had a...