DAC specs: unfamiliar wording and units

I'm translating a document from English that describes a digital ultrasonic testing instrument. The authors are from Israel and are not native English speakers.
Unsurprisingly, the instrument contains a DAC, but the DAC's specs look unusual to me:

• 51dB DAC with 160nsec step size, 51dB/Step slew rate, 500K steps

My guess is that 51dB is the dynamic range. But a step size expressed in time units and not voltage units is something new for me. Can it be that they really meant settling time or conversion time?
With slew rate, I'm accustomed to V/us, so dB/step looks unusual. By step, do they again mean settling or conversion time here?
Finally, can "500K steps" mean the total number of possible output levels?

my fast incompetent best guess is it's likely back to forth decoding as ::

a DAC with 500k divisions(steps#2) resolution -- as 19-bit DAC , with the OUTP slew rate of 51dB(10^(51/20)=apx.355x)/160ns(step#1) . . . . . . . . . ??? to complete a full scale transition takes 0.5M/355×160ns=255µs = f.max.outp = 1 /(2FStransitons x 0.255ms) = 2kHz triangle wave for full amplitude 4kHz for half 8kHz for quarter @17-bit , 16kHz@16bits , 32kHz@15-bit . . . . . . possible but unlikely (unless the wave form at Hi-Fq. doesn't matter)

These are indeed very unusual DAC specifications.

Either they had problems with the translation, or more likely, they made them ambiguous on purpose.