Look sharp. The type plate doesn't say "synchronous stepper motor", it says "synchronous/stepping", indicating a dual use,
either as sine AC driven synchronous or square wave driven stepper. This is possible because a permanent magnet
sychronous motor can be used in both modes of operation. In both cases, the rotor position has a clear relation to the
driving voltage respectively current. In so far, it's position controlled. For optimal drive dynamic and torque, an electronical
controlled synchronous motor can be operated with a rotor position feedback, e.g. a resolver or encoder.