Also, the lens test list here, only lists a normal, non APO, 210 mm version of the Sironar-N:
which is consistent with my own Sironar-N F5.6 210 mm, that doesn't have an APO tag on the barrel. It has a Copal No.1 shutter.
It is not my most used lens, and the few times I used it, I was a bit disappointed with the sharpness compared to my other Schneider-Kreuznach lenses. This comes as no surprise though, as when you look at the above mentioned lens test, the 210 Sironar-N version does not score high points. The APO Sironar-S versions of the 210 mm lenses, do much better though.